[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.