[malky]

These 350 Thunderbirds appear regularly for sale in the U.K.
Usually very low mileage and not much money. I've always thought they would be an excellent base for a trail bike conversion. Any serious mechanical problems? I've heard of premature big end failure, but never from an owner.

[Arizoni]

IMO, they would make a good motorcycle for city riding or riding on a good trail.
They are a bit heavy for any off road riding where things get soft.

As you know, the one in the picture is an AVL.

Although they have some unique problems, like their spark controller, they have several improvements over the iron barrel.

First, they have a steel liked aluminum cylinder so they don't oveheat at higher speeds.
The connecting rod is steel and they use a roller bearing in the connecting rod's big end.
They use a gear type oil pump rather than the ancient piston pump for better oil flow.

A quick way to identify the AVL is to look at the rocker arm covers.
If the joint where they meet the head is angled like the one in the picture it is an AVL.
If the engine and transmission are separate (not unit construction) and the rocker arm covers joint is running parallel with the ground, it is an older Iron Barrel.

The Royal Enfield that is the big seller in India is the new Unit Construction Engine in the 350cc size.  It looks like the 500cc UCE but the cylinder is a bit smaller.
It wouldn't surprise me to see some of these sneaking into the European and UK markets thru a back door somewhere.

[Adrian II]

Ebay UK usually has a least one Thunderbird 350 AVL for sale, they seem to have been imported privately in greater numbers than the 350 AVL Machismo in standard Bullet running gear.

The kick start only models use the CDI ignition which runs independently of the rest of the electrics, so that might be a plus point for turning one into a trail bike. These also have the direct AC powered headlight, so that just leaves the rest of the alternator output to be fed to a regulator/recifier unit with a built-in capacitor (eg Boyer Power Box or its Sparx equivalent) and you can ditch the battery entirely.

The E/S models use a TCI ignition pretty much the same as the 500 Electra-X/AVL Classic, so you'd have to keep the battery even if you ditched the E/S.

All of the ignition components still seem to be available on ebay, as do new barrel & piston sets, I have also seen +0.020" pistons. Same con-rod and big end as the Electra-X, though it ought to have an easier life on a 350. Hitchcock's have SOME parts, the rest are probably still available in India. I couldn't guarantee, but I think they were made in greater numbers for the domestic market than the (mostly export) 500 AVL.

I have been tempted to get a 350 AVL myself on several occasions, but never quite succumbed. No garage room!

A.

[Adrian II]

Just checked, Hitchcock's still have a used 350 AVL engine for sale, looks like an early one which used the Dell'Orto PHBH 28 or 26mm carb instead of the CV Mikarb.

A.

[malky]

Thank you gentlemen, a friend is looking for something more manageable and old school that he can work on and personalise, I think this might just be ticket.

[Adrian II]

Choice of three at the moment, all blue!

http://www.ebay.co.uk/sch/i.html?_odkw=thunderbird&_osacat=422&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.Xthunderbird%20avl%20350.TRS0&_nkw=thunderbird%20avl%20350&_sacat=422#item464f9a3456

[heloego]

And, interestingly enough, one of the Sponsored Links below the ads is for the "Wheel Chair Superstore". 

Sweet prices on those bikes compared to U.S. prices. My Recent Electra AVL purchase was similar, but those rides look in much better condition! 

[malky]

Choice of three at the moment, all blue!

http://www.ebay.co.uk/sch/i.html?_odkw=thunderbird&_osacat=422&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.Xthunderbird%20avl%20350.TRS0&_nkw=thunderbird%20avl%20350&_sacat=422#item464f9a3456

Thanks. I've passed on the info. £1200 one looks worth a punt, seeing as tank, seat, guards, bars etc will get dumped.
Only downside is its the furthest away. I could always offer to ride it home.

[Adrian II]

Malky,

it's not that far from me, you'd be welcome for a coffee or two before the ride home!

They're fairly easy to re-style with stock Bullet parts, here's one another Scottish owner had a go at, though perhaps a silver tank would have looked better:



Heloego,

If the bike to which Malky is referring has been stored outside in the English weather, as the chrome work suggests, it will probably need similar attention to the Electra-X you recently bought.

A.

[malky]

This is what the end result should look like, alloy rims included.

[Adrian II]

If he's throwing the Hitchcock's trials kit at it (the version for the disk front end is slightly different) he could of course junk the slightly bulky instrument binnacle and just fit a single speedometer.

Standard gearing on these is, I believe, 5.3:1 in top on a 16T countershaft sprocket, though I have seen 15T offered if it needs gearing down for trail use.

A.

[Adrian II]

Meanwhile, here's a 4 speed 350 Machismo to add to the mix:

http://www.ebay.co.uk/itm/Royal-Enfield-Bullet-350-Machismo-/142023300396?hash=item21113f952c:g:kV4AAOSwLnBXXcko

Seems to be attracting some bids.

[Adrian II]

Malky,

did your friend ever go for one of these in the end?

A.

[malky]

Malky,

did your friend ever go for one of these in the end?

A.

No, he couldn't start it and decided to buy a new Bullet. I gave him a go of my bike and he loved it. Probably the best decision in the long run. At least I won't get the blame when things go wrong.

[Adrian II]

Is he just going to ride it as is, or is an off-road kit still on the cards?

A.

[malky]

Is he just going to ride it as is, or is an off-road kit still on the cards?

A.

I think he came to the same conclusion as me. (Perhaps with a bit of gentle encouragement) that something in the shed that can be pulled out for a run on a sunny day is better than something in the shed that inevitably ends up as a long term project. Plus the benefits of a warranty from a good dealer. And I'm saying no more as I know he is a browser.

[Impeesa]

I always think this as I travel on interstate highway on my 180 Apache and I cruise at the speed of 90-100 kmph. I had a doubt that can this “beast” as they say is capable of covering 300 kms in one stretch at 90-100 kmph? That too, on Indian highways? Please let me know what is the ideal speed should be to avoid break down of AVL Engine and other aspects?

[El Saif]

I have a 2004 AVL 350cc Thunderbird kick start only.

It can get up to 100 kmh, but feels more comfortable at 80 - 90 kmh.

I have no problem kick starting it. It has never broken down.

In India the AVL 350cc Thunderbird was sold as an upmarket model compared to the Bullet. The Thunderbird has a fuel gauge and a rubber covered gear lever to protect an office worker's shoes.

[AzCal Retred]

The 350 is maybe a 16 HP machine, so speeds greater than 50-55 MPH are going to be a struggle. You need to become a "mechanically sympathetic" rider/owner. There is no reason to or percentage in flogging these engines. Ride aware, the machine will tell you when it's in its happy place. No buzzing, no lugging, let it run "freely".

If you want speed, get a modern design 200cc - 300cc machine. Long stroke engines are built to loaf along economically, not charge hard.

[Mac350]

The 350 is maybe a 16 HP machine, so speeds greater than 50-55 MPH are going to be a struggle. You need to become a "mechanically sympathetic" rider/owner. There is no reason to or percentage in flogging these engines. Ride aware, the machine will tell you when it's in its happy place. No buzzing, no lugging, let it run "freely".

If you want speed, get a modern design 200cc - 300cc machine. Long stroke engines are built to loaf along economically, not charge hard.

Sounds like good advice. Getting to know my new bike I've given it some beans from the lights and on a fast B road got a fair speed without seeming to worry it. It seemed willing. I let it go to wide open throttle in 3rd and 4th and it felt like it was limited by fuel delivery before the engine seemed to mind the revs. I am generally all about mechanical sympathy though and car wise I nurse bangers to their grave, the last 2 to over 300,000 miles on the original automatic gear boxes. I bought the bike for cruising so it should be safe from me

[Paul W]

My iron 350 will rev beyond valve bounce if allowed. It’s just been allowed a bit more gas flow, but nothing too radical. No professionals were involved.

[Adrian II]

Valve bounce is the limiting factor of the 500 AVL at around 5,800 rpm, at least with standard AVL profile cams! The 350 would probably have the same out of the crate. Wonder which cams your bike's previous owner actually fitted?

Remember the AVL design was beefed-up to cope with the demands of the lean-burn top-end, hence the alloy barrel and chunkier cylinder head to cope with the extra heat, and the steel con-rod and needle roller big end to cope with the higher compression. So long as your big-end crank pin was from a good batch(!), it should be a tougher engine than the traditional 350 Bullet and be able to take a fair bit of stick before going bang. At least it's far less likely to put a con-rod through the crankcases than a traditional alloy con-rod Bullet (mostly the 500s) being ridden too enthusiastically.

it felt like it was limited by fuel delivery before the engine seemed to mind the revs

That is, however, one thing you do need to watch out for, make sure your carburettor is jetted up for the mid-range as well as top end if you're using the full performance, I recently had an expensive lesson about this on my Redditch 350 Bullet with a (briefly) higher compression piston. The lean burn top-end will cope better with the extra heat to SOME extent, but... The BS29 can be tuned a bit, but it's not noted for being a performance carb.

Also make sure your petrol tap is free flowing, some Indian taps can restrict the flow for more serious performance, and the resultant over-lean mixture can hole pistons even when the carb is jetted up correctly.

A.

[Mac350]

That is, however, one thing you do need to watch out for, make sure your carburettor is jetted up for the mid-range as well as top end if you're using the full performance,

Thats over my head. I've a pilot jet and a main jet and an idle mixture screw, I can figure how to adjust for idle and full performance but how do I adjust for midrange?

I recently had an expensive lesson about this on my Redditch 350 Bullet with a (briefly) higher compression piston. The lean burn top-end will cope better with the extra heat to SOME extent, but...

Have you got an idea of what the normal and highest before damage range of temperature is for the engine? I've a laser thermometer I could take with me when I'm testing the tuning.

How long does it take you to strip one of these engines down and rebuild? I guess you have to get the piston bits out? And you seem like you're not intimidated by the idea so I guess you've done it a few times.

The BS29 can be tuned a bit, but it's not noted for being a performance carb.

I'm really not trying to get every bit of performance out of this engine. Quite happy with the way it was already just need to get it tuned right and reliable.

Also make sure your petrol tap is free flowing, some Indian taps can restrict the flow for more serious performance, and the resultant over-lean mixture can hole pistons even when the carb is jetted up correctly.

will do! Thats the sort of thing I want to know about now

[Paul W]

The needle controls the mid range. It has grooves and a circlip to adjust the height at which it sits in the throttle slide.

[Mac350]

The needle controls the mid range. It has grooves and a circlip to adjust the height at which it sits in the throttle slide.

Ah thanks. Is it just trial and error on adjusting that?

[Paul W]

Basically, yes!

[Adrian II]

As and when you need to, the top end can be stripped quite easily. The only special tool I needed was a 12mm deep socket. I haven't seen a workshop manual for the 350 AVL, but Hitchcocks' have a free download of the 500 Electra-X manual, some of which will also be relevant to the 350. I came to Royal Enfield after working on (mostly) BSA unit singles, there are enough similarities for me to feel at home!

Somewhere I have some tuning notes for the BS29 CV carb, but that's for 500 use. If it HAS been running fine and surviving a bit of welly without going bang it may be that the carb is already close, though a bigger main jet might help if top end is being held back. I can't advise on actual temperatures, but the holed piston incident also got the engine hot enough to blister the silver paint on the barrel. As I said, your AVL engine should take the heat a little better, it was designed to run as a lean burn engine in Indian traffic!

A.

[Mac350]

though a bigger main jet might help if top end is being held back. I can't advise on actual temperatures, but the holed piston incident also got the engine hot enough to blister the silver paint on the barrel. As I said, your AVL engine should take the heat a little better, it was designed to run as a lean burn engine in Indian traffic!

A.

Ah is that what the lean burn part means? just that its designed to cope with running lean? So it passes emissions running lean and then anyone can play with the carb and its back to a richer mix? 

If I smell burning paint I'll stop for a bit! I've really not driven it hard yet just couldn't resist a bit of a blat. I'd have a hard time on a bike that can't get away from the lights at a reasonable pace though as i used to commute in london and now can never understand anyone on a bike sitting in a line of traffic when they could get to the front and be away. I also wonder about the adventure bike riders with their massive metal boxes making them nearly as wide as a car. Each to their own of course.

[Adrian II]

Ah is that what the lean burn part means? just that its designed to cope with running lean? So it passes emissions running lean and then anyone can play with the carb and its back to a richer mix? 

Pretty much, yes! I've addressed this in a bit more detail on the Trying to determine my model thread. Running lean can do unpleasant things to a conventional Bullet engine as I recently round out, hence the partial redesign of the engine to cope with the extra mechanical stress and heat.

A.

[El Saif]

RE hired Anstalt für Verbrennungskraftmaschinen List or AVL of Austria to redesign the Bullet engine to pass emission laws.

AVL designed a completely new head and barrel and increased the compression ratio to ensure that the fuel burns more efficiently and produce less emissions.

Producing less emissions is more than fiddling with a carburetor.

Because of low incomes and high fuel prices in India, consumers there are obsessed with low fuel consumption.

[Adrian II]

AVL sub-contracted the design of the lean-burn engine to a UK engineer, Dr. Stuart McGuigan, who also designed a diesel Bullet prototype for possible military use. Unlike Indian diesel conversions which simply used a small diesel stationary engine, this one used the Bullet crankcases with a custom 4-valve top end and heavy duty crankshaft, with the 4-speed Bullet gearbox in a Cheney scrambler frame.

A.

[Mac350]

Somewhere I have some tuning notes for the BS29 CV carb, but that's for 500 use. If it HAS been running fine and surviving a bit of welly without going bang it may be that the carb is already close, though a bigger main jet might help if top end is being held back. I can't advise on actual temperatures, but the holed piston incident also got the engine hot enough to blister the silver paint on the barrel. As I said, your AVL engine should take the heat a little better, it was designed to run as a lean burn engine in Indian traffic!

I'm struggling with mid range still and don't want to remove the diaphragm to access the needle without having a repair kit in hand for this 20 year old carb and neither price or hitchcocks have them, and info for these is hard to come by. I'm instead wondering why not just get a better and parts available carb and go from there, rather than spend money on this and still end up changing later. Do you have a recommendation for the 350?

[Paul W]

Ask every forum member and almost  all will give a different preference for carburettors (same with oil and any number of other subjects).

However, I've been very pleased with my Wassell 626R carburettor. These come with a short bellmouth already fitted and because I wanted to keep it but don't like running any engine without an air filter I bought a 48mm "pit bike" foam filter which fits nicely over the bellmouth. The carb came with a 160 main jet, which has proved to be exactly right for my bike (which has a gas flowed head and high compression Meteor Minor piston).

https://britbikes.co.uk/products/carburettor-wassell-right-hand-26mm-bore-4-stroke-626-300-6-26r

The one other thing I have done to it is to fit an anodised throttle slide, to prevent wear. The original is the same material as the main casting, which imho isn't the best thing.

[Mac350]

The diaphragm felt like it would rip if i pulled it more but as I'm thinking of getting another carb anyway i pulled enough and got it off without damage. The clip was on the top position so I lowered it to the bottom position and it has much improved the situation but it still struggles under load accelerating, particularly up hill in the mid rev range, it hesitates intermittently like its misfiring. But it charged up a hill that it felt like it might not make before I moved the clip, but i might have started up above the mid range and kept it high revs. Seems like midrange is where all the problem is. Could the carb be too big? Standard is 26mm but I found some talk on an indian forum saying 29 is all they can find for a replacement, it might have just been put on for no good reason. Even if I buy a new carb (frankly I like the look of the amal/wassell carb with a cone filter) I will need to know which size to order.

[Mac350]

Ask every forum member and almost  all will give a different preference for carburettors (same with oil and any number of other subjects).

However, I've been very pleased with my Wassell 626R carburettor. These come with a short bellmouth already fitted and because I wanted to keep it but don't like running any engine without an air filter I bought a 48mm "pit bike" foam filter which fits nicely over the bellmouth. The carb came with a 160 main jet, which has proved to be exactly right for my bike (which has a gas flowed head and high compression Meteor Minor piston).

https://britbikes.co.uk/products/carburettor-wassell-right-hand-26mm-bore-4-stroke-626-300-6-26r

The one other thing I have done to it is to fit an anodised throttle slide, to prevent wear. The original is the same material as the main casting, which imho isn't the best thing.

Sounds good do you have a photo handy of the set up? I guess it means losing the fake airfilter box, i notice the bracket for that looks like it would just unbolt. I can fabricate a back for the battery box to tidy that up... or could I put it in the vacated air filter box???  too much fun all this

[Adrian II]

Since the original A350 Machismo was designed for a 28mm, that's where I'd go., though a well set-up 26mm Mk1 (clone or genuine) won't be far off.  I think I mentioned I actually have a little-used Dell'Orto PHBH28, same carb as originally fitted to the early examples, which may very well fit the carb rubber/flange thingy that's on there now (35mm diameter stub), save you buying an adapter for one of the Wassell Mk1 clones?

Yours for a fraction of the price of a new one from Eurocarb, already!

https://www.dellorto.co.uk/shop/dellorto-motorcycle-carburettors-parts/complete-carburettors-dellorto-motorcycle-carburettors-parts/phbh-26-to-30mm/r3340-dellorto-phbh-28bd-4-stroke/

A.

[Mac350]

Since the original A350 Machismo was designed for a 28mm, that's where I'd go., though a well set-up 26mm Mk1 (clone or genuine) won't be far off.  I think I mentioned I actually have a little-used Dell'Orto PHBH28, same carb as originally fitted to the early examples, which may very well fit the carb rubber/flange thingy that's on there now (35mm diameter stub), save you buying an adapter for one of the Wassell Mk1 clones?

Ah the battery already has a little shelf for it in the toolbox and I don't even need to change any wiring, just reroute it. Stick the tools in the other side and jobs a goodun 



Which means I have to go bling on the carb. And the metal flange/spacer with amal-esque carb with cone filter is calling but thanks for the offer

[tooseevee]

The clip was on the top position so I lowered it to the bottom position and it has much improved the situation but it still struggles under load accelerating, particularly up hill in the mid rev range, it hesitates intermittently like its misfiring. But it charged up a hill that it felt like it might not make before I moved the clip, but i might have started up above the mid range and kept it high revs. Seems like midrange is where all the problem is.

           Just a SWAG here, but I'm thinking you should go back to the middle notch on your needle clip & tweak from there. I'm just guessing going to the bottom notch has blown a lot of your midrange happiness.

            Good luck. I spent a lonnnng time getting the TM 32 (totally new animal to me) on my '08 AVL to be nice (the BS 29 went away when ACE did the head).

[Mac350]

However, I've been very pleased with my Wassell 626R carburettor. These come with a short bellmouth already fitted and because I wanted to keep it but don't like running any engine without an air filter I bought a 48mm "pit bike" foam filter which fits nicely over the bellmouth. The carb came with a 160 main jet, which has proved to be exactly right for my bike (which has a gas flowed head and high compression Meteor Minor piston).

https://britbikes.co.uk/products/carburettor-wassell-right-hand-26mm-bore-4-stroke-626-300-6-26r

The one other thing I have done to it is to fit an anodised throttle slide, to prevent wear. The original is the same material as the main casting, which imho isn't the best thing.

Unfortunately the 626 isn't available anymore according to Mr Price and seems out of stock everywhere. Minimum size I can get is 28mm of the 900 series which does worry me a little. The current 29mm being CV though maybe not comparable but thinking about it maybe the being oversized makes sense that it would effect the midrange the most, once revs are high enough there is enough pull to get it working despite being a bit large... though why would it be ok on the lower range? I have no idea if i'm understanding this right or not anyway  Mr Price doesn't think it will be oversized so we'll see how it goes.

Any trouble with making the flange work?

[Mac350]

           Just a SWAG here, but I'm thinking you should go back to the middle notch on your needle clip & tweak from there. I'm just guessing going to the bottom notch has blown a lot of your midrange happiness.

            Good luck. I spent a lonnnng time getting the TM 32 (totally new animal to me) on my '08 AVL to be nice (the BS 29 went away when ACE did the head).

I did wonder about going just one but the midrange was so bad before I thought just go all the way and if i then have a different problem go back to the middle. I just have the same problem but not as bad so I'm thinking I should try adding a fourth notch if anything  But if i was going to keep it yes i'd try the middle notch for the sake of 10 minutes doing it. I suppose a flat slide 32 isn't equivalent to a CV 32 so it doesn't tell me much but you did get it working nicely in the end?

[Adrian II]

Unfortunately the 626 isn't available anymore according to Mr Price and seems out of stock everywhere. Minimum size I can get is 28mm of the 900 series which does worry me a little. The current 29mm being CV though maybe not comparable but thinking about it maybe the being oversized makes sense that it would effect the midrange the most, once revs are high enough there is enough pull to get it working despite being a bit large... though why would it be ok on the lower range? I have no idea if i'm understanding this right or not anyway  Mr Price doesn't think it will be oversized so we'll see how it goes.

Any trouble with making the flange work?

Like I said, the A350 was DESIGNED for a 28mm carburettor, even if later cylinder heads might have been finished with smaller ports - I think you mentioned something about die grinders... Genuine Amal 26mm Mk1s in standard and Premier form are still available, but you'll have to prize your wallet open a bit further compared to a Wassell! 

The very early 350 Machismo heads had a cast stub to mount the carb on via a rubber connector, with a later heads losing that in favour of a flange with studs centres drilled at 60mm, though if they're the same as the 500s in this respect they use M6 allen screws instead of studs. Early example here:

https://accessories.hitchcocksmotorcycles.com/39024?cont_page=Engines

The common Amal Mk1 adapter for the Bullet has 58mm stud centres for the 500 Iron Barrel heads instead of the AVL's 60mm, so a teeny bit of work with a rat-tail file might be needed.

A.

[Mac350]

Like I said, the A350 was DESIGNED for a 28mm carburettor, even if later cylinder heads might have been finished with smaller ports - I think you mentioned something about die grinders... Genuine Amal 26mm Mk1s in standard and Premier form are still available, but you'll have to prize your wallet open a bit further compared to a Wassell! 

I checked and it was quite a bit further! My hope is that the mikuni copy was just a poor carb to start with or sufficiently worn to stop it working well and the new carb will sort everything out whether its 26 or 28. I noticed the 28s being the evolution versions already have the upgrades of the premier amal and what Paul opted for with his Wassell. Should know by the weekend if it does the job. I ordered the Snidal printed manual but no sign of it yet. Most of the stuff so far is quite straight forward to take apart but hopefully it will give some more insights into what I'm doing

The very early 350 Machismo heads had a cast stub to mount the carb on via a rubber connector, with a later heads losing that in favour of a flange with studs centres drilled at 60mm, though if they're the same as the 500s in this respect they use M6 allen screws instead of studs. Early example here:

https://accessories.hitchcocksmotorcycles.com/39024?cont_page=Engines

The common Amal Mk1 adapter for the Bullet has 58mm stud centres for the 500 Iron Barrel heads instead of the AVL's 60mm, so a teeny bit of work with a rat-tail file might be needed.

A.

It is the 60mm hole centers and Henry did mention that I'd need to work on it a little. No worries.

Did I see you mentioning its worth getting a NGK plug cap? Any particular one? I didn't even know they had various resistances until I looked. Any other cheap improvements you can think of?

[tooseevee]

I did wonder about going just one but the midrange was so bad before I thought just go all the way and if i then have a different problem go back to the middle. I just have the same problem but not as bad so I'm thinking I should try adding a fourth notch if anything  But if i was going to keep it yes i'd try the middle notch for the sake of 10 minutes doing it. I suppose a flat slide 32 isn't equivalent to a CV 32 so it doesn't tell me much but you did get it working nicely in the end?

        I did not know that that carb's needle only had 3 notches.

        Yes. I got it sweet as tupelo honey after much tweaking & learning by failing & doing something else; one thing at a time. Over & over & over  Now I can't ride it for the 4th year 

[Mac350]

        I did not know that that carb's needle only had 3 notches.

        Yes. I got it sweet as tupelo honey after much tweaking & learning by failing & doing something else; one thing at a time. Over & over & over  Now I can't ride it for the 4th year 

Sorry to hear you're off the road.

Your signature led me to your battery thread and finding this photo. Looks great. I'll do the same. Relatively easy to declutter these it seems, without needing to do anything irreversible.



I'll swap for a smaller AGM battery like the one you used next time its needed. Kick start only and I've put a LED light bulb in the rear and the front runs off the engine so there is very little for it to do. Actually why do I even have a starter type battery I should have a leisure one that can discharge lower without harm. Or just stick a couple of AAs under the seat 

But thats the same carb I had, the BS29. I think I'm going to be glad I just ditched it like everyone else seems to! Was there a reason you got rid of the cone and have the bigger air filter on the bike now?

[Paul W]

        I did not know that that carb's needle only had 3 notches.

        Yes. I got it sweet as tupelo honey after much tweaking & learning by failing & doing something else; one thing at a time. Over & over & over  Now I can't ride it for the 4th year 

Ten years ago I was into tuning the modified engine of my competition car which back then had SU carbs. These carbs have a fixed needle, ie they don’t have grooves and a circlip to adjust the mid range mixture - the needle is held in place in the throttle slide with a grub screw.

After getting frustrated by buying so many recommended needles (quite expensive) that weren’t right I gradually richened the mixture to what it needed to be by carefully slimming down needles that were too weak; I adjusted them using a pillar drill and very fine wet and dry paper, used wet.  There’s no reason why this couldn’t be done for a motorcycle carb.

[tooseevee]

Ten years ago I was into tuning the modified engine of my competition car which back then had SU carbs. These carbs have a fixed needle, ie they don’t have grooves and a circlip to adjust the mid range mixture - the needle is held in place in the throttle slide with a grub screw.

After getting frustrated by buying so many recommended needles (quite expensive) that weren’t right I gradually richened the mixture to what it needed to be by carefully slimming down needles that were too weak; I adjusted them using a pillar drill and very fine wet and dry paper, used wet.  There’s no reason why this couldn’t be done for a motorcycle carb.

       I learned how to tune & balance SUs on a '59 Volvo PV 544 using the "rubber tubing stuck in the ear" method. Marvelous little engine.

[Mac350]

Ten years ago I was into tuning the modified engine of my competition car which back then had SU carbs. These carbs have a fixed needle, ie they don’t have grooves and a circlip to adjust the mid range mixture - the needle is held in place in the throttle slide with a grub screw.

After getting frustrated by buying so many recommended needles (quite expensive) that weren’t right I gradually richened the mixture to what it needed to be by carefully slimming down needles that were too weak; I adjusted them using a pillar drill and very fine wet and dry paper, used wet.  There’s no reason why this couldn’t be done for a motorcycle carb.

Thats a good idea, less chance of getting it wrong than trying to put a lower groove in it without a micro lathe, though it would mean never being able to get the leanest setting again. I can't help wondering why it was on that setting. Surely it must have worked at some point or it would have been moved already. So what changed??

I was thinking of putting the needle in my pillar drill and a very fine Dremel cut off wheel in a machine vice that's on a sliding table i have mounted on the drill table and bringing the cut off wheel to the spinning needle. But it feels like there must be something wrong with the carb that this would be fighting against rather than fixing. I'm going to take it off again and dismantle it and put it in an ultrasonic bath I use for work though I just want the amal and cone filter look now anyway

[tooseevee]

Sorry to hear you're off the road.

 Was there a reason you got rid of the cone and have the bigger air filter on the bike now?

           When I had the head reworked for better flow (just better all around than the factory head) by Ace in 2014 I also went with the Ace air box. It provides a plenum; a quiet, undisturbed, safe place for the air to sit and wait to be sucked in rather than a cone out in the airstream. After the headwork, the TM32, the exhaust improvements, the Pertronix, the engine just performed all around better; quicker easier revving, smoother, quicker to a given speed in any gear. Just all around way better than stock. It went faster in 4th than I ever really cared to go & 5th was just loafing along at 60.

     I have the flowbench charts, but my feelings on on-the-road performance are all seat of the pants. It was just an overall better engine. Oh yeah & the switch to Champions over the NGKs was a vast improvement I really can't explain except for the fact that they stayed cleaner. I tried 2, 3 & 4 heat range. I think I settled on 4. 

            There's a lot written about all this & tuning & improving the AVL back in the dusty stacks. Back in 2012, 13, 14 & forward. And a lot of the ironhead stuff back then also applies.

             My biggest mistake back then was not having Ace install an ironhead decompressor in the head when he did all the other work.

[Mac350]

Oh yeah & the switch to Champions over the NGKs was a vast improvement I really can't explain except for the fact that they stayed cleaner. I tried 2, 3 & 4 heat range. I think I settled on 4.

Any particular plug or will it be whatever the suggested equivalent is if i search?

My biggest mistake back then was not having Ace install an ironhead decompressor in the head when he did all the other work.

Mine works ok so far. I dont need it for starting but it stops the engine well enough. I just slowly press it over and it does its thing.

[tooseevee]

..... though I just want the amal and cone filter look now anyway

   Yes. They DO look good with an Amal & a cone. No dowdaboutit 

[tooseevee]

Any particular plug or will it be whatever the suggested equivalent is if i search?

        I played with Champion RN2C (818), RN3C (880) & RN4C (803). I think I stayed with the 3 the last years I could ride as it was not getting black at all under all kinds of riding.

        Why I tried the Champion (I should have thought to do it WAYYYY sooner) is that I was having trouble kick starting it cold the very first start of any morning. After it was warmed up it was a one kick starter the rest of the day.

        I chased it as a carburetor problem until I was so pissed & blue in the face I was going to burn the bike.

        I put the first Champion in & got a cold kick start right away (2 kicks key off, one kick key on) in the morning for the first time & I then kicked myself in the ass around the block for not doing it sooner. This is with same carb setup & yes, I had cleaned & kissed & hugged the enrichener multiple times.   

      Here's a link to one of my last rides. As you can see in the very beginning I'm getting pretty much crippled up & my kicks are pretty weak. And the sound is terrible.

https://www.youtube.com/results?search_query=2008+Royal+Enfield+14+mile+ride


         Remember Champion plugs are made all over the place now just like all the rest so caveat emptor. And use plenty of anti-seize. The threads are rough and the aluminum is, well, aluminum. And Champion plugs are opposite of NGK heat numberwise. Higher number is hotter; the 4 is hotter than the 3. And I used the R plug because I got rid of the crappy stock tin can resistor plug cap. I don't think it matters to these engines anyway. R or no R, they run just fine.

[Mac350]

        I played with Champion RN2C (818), RN3C (880) & RN4C (803). I think I stayed with the 3 the last years I could ride as it was not getting black at all under all kinds of riding.

        Why I tried the Champion (I should have thought to do it WAYYYY sooner) is that I was having trouble kick starting it cold the very first start of any morning. After it was warmed up it was a one kick starter the rest of the day.

        I chased it as a carburetor problem until I was so pissed & blue in the face I was going to burn the bike.

        I put the first Champion in & got a cold kick start right away (2 kicks key off, one kick key on) in the morning for the first time & I then kicked myself in the ass around the block for not doing it sooner. This is with same carb setup & yes, I had cleaned & kissed & hugged the enrichener multiple times.   

      Here's a link to one of my last rides. As you can see in the very beginning I'm getting pretty much crippled up & my kicks are pretty weak. And the sound is terrible.

https://www.youtube.com/results?search_query=2008+Royal+Enfield+14+mile+ride


         Remember Champion plugs are made all over the place now just like all the rest so caveat emptor. And use plenty of anti-seize. The threads are rough and the aluminum is, well, aluminum. And Champion plugs are opposite of NGK heat numberwise. Higher number is hotter; the 4 is hotter than the 3. And I used the R plug because I got rid of the crappy stock tin can resistor plug cap. I don't think it matters to these engines anyway. R or no R, they run just fine.

You've got an amazing place to tinker with your bike anyway. And ride without a helmet as you like. And empty roads. And sunshine damn it   

Is your bike the 500 then? I need a shorter plug and the only option I'm seeing is the L82C https://www.bikersdirect.co.uk/guide/champion-spark-plug-application-guide-for-british-motorcycles

I see lots of variations listed here https://www.sparkplug-crossreference.com/search/l82c  but i only see the one type for sale. I'll give it a shot though at some point

[tooseevee]

You've got an amazing place to tinker with your bike anyway. And ride without a helmet as you like. And empty roads. And sunshine damn it   

Is your bike the 500 then? I need a shorter plug and the only option I'm seeing is the L82C https:

       Yes. I hope very few people watch it. I don't want more people moving here 

       Yes. My '08 is a 500 AVL Classic. I can't give (& should not have been giving) advice on 350s. I lost my mind (temporarily) 

       We have (both of us) to keep that in mind.

        The UCAL BS 29 uses Mikuni jets. You just need to know the Mikuni # & the Series Designation.

           Adrian knows & will respond in time. I would need an hour to go back thru my knowts & invoices. I'm SURE I ordered Mikuni jets for that carb.

     Adrian will help you soon, I'm sure.

      You probably should put a new diafragamm in that carb, also, if yer gunna keep it

[Adrian II]

Made it.

I have been trying to find my old tuning guide (actually someone else's, which I copied a while back) for the CV29 carb for the 500 AVL, but it's on a USB memory stick - somewhere, if I can still find it. Assuming it's not lost forever, it might be adjustable for the 350 AVL, reduce jet size by ?% sort of thing.

Oh well, keep looking,

A.