Author Topic: Has anyone done a C5 carb conversion  (Read 2038 times)

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suitcasejefferson

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Reply #30 on: March 12, 2021, 07:56:37 am
You actually don't pay a price for it. It actually pays you. And not just by making things the way they should be (a motorcycle should have a carburetor not a computer)  I paid about $350 USD for the conversion kit including the carb. And it works so much better than the EFI it's almost unbelievable. But perhaps just as important is that you are now riding a machine, not a computer. There is a great deal of satisfaction in that. I could never enjoy riding a motorcycle controlled by a computer. Not even if it did work well.

But lets look at the financial side of it. Compare the price of that carburetor kit to the price of a $500 electronic tuner. Compare it to the price of an EFI fuel pump (FUEL PUMP MODULE
Product code: 571052 (2013 B5 Bullet)
Normal Qty Required: 1
£429.08 exc. VAT
£514.90 inc. VAT)

Or an ECU. Or a throttle body. On average, an EFI bike has about $2K worth of parts in the fuel system, compared to maybe $500 for a carbureted bike. And a carburetor will literally last forever. The float needle valve and seat are about the only wear parts in one. Maybe the slide. And if something should go wrong, like it might get plugged up, you can usually fix it beside the road. There have been several times during the past few decades I have gotten bad gas, and the bike quit running out on the road. All I had to do was clean out the petcock and/or carburetor. It would have almost certainly ruined the fuel pump on an EFI bike.

Somebody mentioned points. I would love to be able to have points. You can troubleshoot and usually fix a points problem beside the road. Not much you can do when a CDI or pickup coil fails but call a tow truck. Points do not require constant attention. I've been driving an old car with points for more than 5 years without ever touching the points.

The only bad thing I can think of when it comes to old school motorcycle design is tube type tires. They are dangerous when they blow out at highway speeds (tubeless tires almost never blow out) and they are almost impossible to repair beside the road. They are completely impossible to repair beside the road if you don't have a center stand, which at least RE bikes still have. Yet on newer bikes almost everything has been replaced with something "modern" that makes it a lot harder and more expensive to repair EXCEPT the tires. I just can't help but laugh when I see a bike with EFI, ABS, CDI ignition, electronic traction control, computer controlled rider modes, and on and on, and TUBE TYPE TIRES. They removed all the good stuff and replaced it with junk, except for the ONE thing that really did need to be upgraded to something more modern. And tubeless tires aren't even electronic.

As I said, I believe the UCE engine is better than the pre unit engine/transmission. But IMO the electronics were a step in the wrong direction. All the 500 singles were somewhat poorly made compared to the new twins. But they have character and provide a wonderful riding experience that the new twins cannot begin to match. That long stroke single has a sound and feel that no modern bike has. It may not be powerful or fast, but to me that is not what riding a motorcycle is all about.
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viczena

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Reply #31 on: March 12, 2021, 09:07:09 am
I still remember the time, when there were only carbs. And most of the bikes had points. They were quite unreliable and most of the bikes ran like shit.

On every trip you could see at least one bike on the side of the road with a defect. Either ignition or fuel.

I even remember that you had to change the main jet when driving into the mountains, and back again when you descend. And dont forget. Else your pistons would melt.

No thanks. I want to ride a bike, not spend time with repairs. As cheap as they seem to be.

I know that time softens memory of the past. Good ole times...
« Last Edit: March 12, 2021, 10:04:05 am by viczena »
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Adrian II

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Reply #32 on: March 12, 2021, 11:44:30 am
It IS possible to pay crazy money on carbs, I notice H's haven't offered a carb conversion for EFI Bullets based on the Keihin FCR range, have they? Even the Chinese copies of these come in at around £150/$210. That's just to pluck one example out of the ether. But while the K-word is still in our minds, a suitably jetted clone of the Keihin PWK could save big bucks over the Mikuni (or Amal!) and still perform well. They were offered by CMW as an upgrade for older model Bullets a few years ago, but since then prices have tumbled.

If suitcasejefferson's Bullet now performs better than it should(!), that sounds like a win.

A.
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TrianglePete

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Reply #33 on: March 12, 2021, 12:31:04 pm
As a 72 year old motorcycle rider and mechanic, I love these bikes I also Love my Grandchildren.

Everyone wants to make the UCE 500 and 535 more usable on modern roads. We seem to blame the FI

and computer  when in fact the 500 and 535s are built with 350 cams.  No matter what we do you can

NOT overcome a lack of cam duration....   Look up the part #  please.


Richard230

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Reply #34 on: March 12, 2021, 02:08:34 pm
I think you can thank (or condemn) government regulators for all of that modern electronic stuff on your Royal Enfield. I bet that if they didn't force RE and many other manufacturers to modernize their lumps with EFI, ABS, catalytic converters, air-injection, exhaust sniffers, etc., etc. RE would never have stuck that stuff on their bikes and your Bullet would still have a carburetor, ignition points and drum brakes.   :o Would that be better or worse than the current versions?  But at least you are still getting tube-type bias-ply Avon Slipmaster II tires on some models - along with a push-rod long-stroke single. So there is that.  ;)
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TrianglePete

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Reply #35 on: March 12, 2021, 03:20:42 pm
There is no excuse for poor engineering. 

      If you always do what you always did

      You will always get what you always GOT.

   I am for leaving the environment better than I found it        I guess I payed attention in scouts.

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ace.cafe

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Reply #36 on: March 12, 2021, 11:57:14 pm
A couple of comments on things previously mentioned above.

First, the pre-unit Bullets with points ignition really don't have much of an advance curve because the crude mechanical advance bobweights swing out to full advance all at once at around 1500 - 1750 rpm, so you are essentially at full advance all the time you are in motion at any sort of road speed. The problem with that is that full advance shouldn't really be reached until torque peak at around 3500 rpm. At full advance below 3500 rpm, if there is significant load from hard acceleration or hill, the system has no way to retard the spark, so heat and detonation(pinging) ensue with often calamitous result.

Regarding the Bullet cams, all Bullets had the same cams in the 350 and 500 since the inception in the early 1950s. They did vary by engine evolution in that pre-unit Bullets all had the same cams, AVLs all had the same cams, and UCE all had the same cams. This should not be construed that the 500 breathes the same as the 350 because all the top end(ports, valves, inlet and exhaust manifold) sizes were commensurately larger on the 500 so that breathing was suitable for the difference in cylinder volume. The cams are operating the valves the same, but a whole lot more air is coming in/out of the 500 during that time that the cams have the valves are open due to breathing tract sizes.
Not to say that improvement wasn't possible, but some people may misunderstand.
« Last Edit: March 13, 2021, 12:00:17 am by ace.cafe »
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TrianglePete

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Reply #37 on: March 13, 2021, 12:21:23 am
A small duration cam for a 350 is not enough for a 500 or 535. 

No mater it is like strangling the bigger engine.   It is good enough for India .

We in America need a 500/535 to breath free enough to keep up to traffic .

They should have designed a proper cam for export.


AzCal Retred

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Reply #38 on: March 13, 2021, 04:44:27 am
Ace - Should I get stronger springs, taylor the advance to delay full advance to 3000 - 3500? I've never bothered to put a light on mine, just set up the static at 0.8mm & make sure the flyweights operated smoothly. There are a lot of hot rod springs available. If it improves drivability & "survivability" it seems worthwhile.
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ace.cafe

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Reply #39 on: March 13, 2021, 11:56:00 am
Ace - Should I get stronger springs, taylor the advance to delay full advance to 3000 - 3500? I've never bothered to put a light on mine, just set up the static at 0.8mm & make sure the flyweights operated smoothly. There are a lot of hot rod springs available. If it improves drivability & "survivability" it seems worthwhile.
There have been some springs tried, such as Hitchcocks stronger springs. They delayed it a couple bundred rpm later. If there are other kits available, I haven't seen any actual results shown anywhere.
I once read about a guy who played around with modifying(lightening) the bobweights and using 2 different springs, but I can't remember exactly what he did. It never achieved the goal, but it got more toward a curve shaped advance than just the stock springs.

It should be possible to mod the distributor for a manual cable type spark advance/retard system like the very old bikes had. Maybe even a small Lucas vacuum advance unit could be cobbled on there, like from an MGB or something?. I never tried it.

The easiest thing to do is just get the revs up over 3500 rpm if you are giving it increased load from a hill or hard acceleration. Then, it won't need to retard the spark because its above torque peak rpm.
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Adrian II

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Reply #40 on: March 13, 2021, 12:30:46 pm
AzCal, try a magneto! Lucas K1F or BTH KC1 (with manual advance in view of the above) are probably the easiest to retro-fit to an Indian Bullet's crankcases if you're not fitting a Lucas SR1

Not a straight bolt-on fit with either of these two, as there are some minor modifications required, but a fairly lazy afternoon's work would see you up and running.

A.
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AzCal Retred

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Reply #41 on: March 13, 2021, 04:54:51 pm
Summit Racing has a package of 3 pairs of springs from soft to firm for $13, I think that'll be good enough for a 6.5/1 & 5500 RPM motor. I can take the beast outside and do this when I change primary oil. A minute or so of unloaded running isn't going to zorch the clutch or primary chain. It'll be a good experiment, any improvement will be a good improvement, yes?

The spark advance cable idea is interesting to me, you'd be able to ping time on the fly. But we'll try the low hanging fruit first.


https://www.summitracing.com/parts/sum-850120?seid=srese1&gclid=CjwKCAiA4rGCBhAQEiwAelVti18odmziqM_KEfxFt0MVNYlgJUowTdjlLqvGmxxJgK1i6l9DoWtorhoCeCUQAvD_BwE
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jez

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Reply #42 on: March 16, 2021, 09:19:19 pm
Actually a smaller displacement engine would if anything have a more extreme cam. It's as Ace says. The cam  is set up for indian conditions, so low revs so as not to stress poorly matched parts on slow roads.  My carbed  535 returned over 90 mpg without me even trying. It revs to 6 and pulls well with no flatspots or advance problems. And growing up with and presenly owning manual advance bikes I know the signs. It has aftermarket cams and valve gear and a lot of the electrics have been junked.
However there is very little room so anything big bodied simply doesn't fit easily hence Hitchcocks using 32mm Amal and Mikuni slide carbs.
That's smaller than the injector bodies and it has been reported that the carb on it's own doesn't give a higher top speed, may lose a bit at top revs on the 535. Some of the early XT/TT500 engines used a 32 but they latterly settled on a 34, and that engine was known as a poor breather. My KLX 250 came with a 32 though that bike is admittedly over carbed. There's an awful lot of people on this forum arguing on stuff they don't really understand. I don't understand electrics at all so  I waited till a carbed 535 came up.
« Last Edit: March 16, 2021, 09:32:05 pm by jez »


Snotball

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Reply #43 on: March 16, 2021, 11:03:46 pm
If I remember correctly my Cast Iron from 2005 had a 28mm Mikarb as standard. With free flowing exhaust and intake plus some rejetting that bike easily out performed the 2019 UCE I own now in all areas except outright top speed which was around 10kph slower on the older bike. When it came to climbing hills and holding higher gears the cast Iron won hands down. So newer doesn’t necessarily mean better!


suitcasejefferson

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Reply #44 on: March 17, 2021, 08:19:46 am
I don't think the 500 single should be ridden much above 55 mph, no matter what cam is in it. One reason for that is it's overall poor build quality and materials. It is also an ancient design. It works wonderfully when ridden at the speeds it was originally designed to be ridden at. A long stroke engine will always have a lower redline than a short stroke engine. It will have more low end torque, but less total hp. But like I said, power is not why I ride motorcycles. I ride them for the experience. The feel and sound. At 55 mph you can almost count the firing pulses of that long stroke single. It doesn't sound like a sewing machine like "modern" short stroke engine. The only other new motorcycle I like the feel and sound of besides the RE 500 single is a Harley Davidson, and I own a 1200 Sportster. It is not powerful or fast, but again it provides that wonderful feel and sound. And unlike the RE, it will easily keep up with highway speeds without self destructing. But it is more fun being ridden slower.

As for carburetors and points, there is nothing wrong with the concept. Vintage bikes had poorly designed and poorly made carburetors and ignition systems. With modern designs, materials, and manufacturing methods it is now completely possible to build a carbureted bike with a points ignition that would run almost forever without problems. The Amal carburetor on my RE, and the Keihin and Mikuni carburetors on my other bikes work perfectly. From 1200 feet where I live to over 8000 feet. And there is no reason they cannot continue to do that for the life of the engine. My 1964 Ford has been running fine for more than 5 years without the points being touched. I probably should replace them soon. True, new points and condensers are probably a great deal more reliable than those made in 1964. A modern points system could be made to last 20 years and 200,000 miles without attention. And yet still be easy to maintain and work on, and cheap to repair if something did go wrong. Don't let problems with poorly designed and built ancient carburetors and ignition systems make you believe that the concept is bad and that new electronic technology is needed. It isn't. What's needed is better designed and built carburetors and ignition systems that work the same way the old ones did.

Drum brakes. Yes a disc is somewhat more efficient than a drum. And on some bikes it's even a good idea, at least in the front. Nothing but large touring bikes need a rear disc. I have never ridden a bike with rear drum brakes that I could not easily lock the rear wheel on. About 90% of the braking is done by the front brake anyway. The rear brake is just for fine tuning braking control. As for a front drum, I have had a number of bikes with those, and could lock the front wheel on all of them. Something that is almost impossible to do on the RE with a disc front brake. Drum brakes look way better than disc brakes. Disc brakes are downright ugly. And on a motorcycle they are right out there for all the world to see. No they don't belong on high powered sport bikes (but then I don't believe bikes like that really belong on the road anyway, they were designed for racing) or big heavy bikes. But on a RE 500, a well made front drum (like on Japanese bikes) would not only out perform the disc that is on the UCE models, but look 10 times better as well. A lightweight 55 mph motorcycle does not need racing brakes. If you can lock the wheel, you have enough brakes. You just need to learn to stop without locking the wheels, rather than having a computer take over and do that for you. Being in total control of a machine is a huge part of the enjoyment of riding. Learning proper braking, throttle control, shifting, etc. is not unlike learning how to play a musical instrument. I don't think that playing a guitar (which I used to do before I got hit with arthritis) or a piano that corrected your mistakes would be much fun, since it would require very little skill.
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