Stumbling at 1/8 throttle

Patton wrote:

jumpship wrote: ...Clymer's said the more in you go the richer,and the bike is definitely asking for fuel which is the only reason why i went all the way in....

CV34 carb has a vacuum operated slide, and does NOT have a manually operated slide.

The Clymer is likely addressing a manual slide carb with a pilot air screw, and not a CV carb with a pilot "mixture" screw.

The side-located pilot air screw on a manual slide carb allows more air into the fuel mixture as it's turned out counterclockwise, and less air into the fuel mixture as it's turned in clockwise.

In the case at hand, would start with 2 turns out from lightly seated.

Good Fortune!

Often wondered about screw settings...every engine is going to require different turns-out depending on multiple factors, including not only the condition of the engine as a whole, but each cylinder's draw of air/fuel mixture requirement due to differences in compression, and potential air leaks and internal differences from one carb to the next. The variables are enough to drive a person nuts, so don't get upset...just take a deep breath, and start over if you have to.
Using the Gunson Colortune gizmo finally brought things together for my engine, after years of fiddling with the screws, thinking they had to be set the same across the rack.

jumpship wrote: Here's what I did on my 1 hour lunch. I started at 2 open, and results were very similar, than I went to 4, got a bit better. And believe it or not I went to 6 turns out, and the moment I started her up and got on the bike the issue was resolved and i mean totally! But after riding around for like 10 minutes the trouble came back. And the idle would be normal but drop suddenly.

Idle varying along with lean running condition sounds like an air leak somewhere.

jumpship wrote: Hmm might have to turn your head a bit LOL but here's what the manual said. I did find it funny that in would be rich... maybe I'm reading it wrong? I haven't tried the 2 turns out yet I'll let you know in a bit

Not reading it wrong, but reading about the WRONG carb, because the cited Clymer paragraph is about manual slide carbs with a pilot AIR screw.




The CV carbs at hand do not have a pilot "air" screw.

The CV carbs at hand have pilot "mixture" screws.

Good Fortune!

I'm having a hellacious time trying to tune my bike with the stock #35 pilot jets. I installed pod filters and a jet kit from 6Sigma Jets, but I can't even keep my bike running long enough to balance the carbs. The carbs are freshly cleaned and bench synced. The jet kit came with #38 pilot jets that don't fit my carbs... Here is the pic of the stock pilot jet vs. the new ones they sent me. (obviously different thread patterns, and the head of the jet is too big to fit into the hole where the jet screws in.

In my latest attempt, I took the stock jets, shortened them to match the length of the ones they sent me, drilled out the main hole to match the diameter, and drilled atomization holes (1/64 in. as tiny as I could find). My modifications were successful to the eye, but the bike still hasn't responded. I know I probably ruined perfectly good stock jets, but if anyone has any advice, I would love to hear it...

I got my bike at around 95% im thinking i will swap out primary main jets for bigger ones, THAT they do have, just to experiment. calebstrawn what are your needles at im assuming your kit came with adjustable clip needles? also the mixture screws on top. I would honestly order the oem #35 pilots again (atleast the'yre available), anyways lemme know what steps your at ill see if i can input any, i've been battling this bike for weeks now. Oh and also get new boots that connect from the intake manifold to the carb, even if they look ok.

Jumpship, My boots were cracked when I bought the bike, but it would still run pretty well as long as I kept a little grease smeared on the boots ( I put about 1,000 miles on the bike last summer riding back and forth from Austin to Dallas). I knew they needed replacing though, so that was one of the first things I replaced. I've got larger main jets in #107.5 on cylinders 1 &4 and #110 on 2&3, per the jet kit instructions (I'm riding at about 1000ft above sea level, and have pod filters) My needles are the shim type, I've got 2 shims in now. Bike revs smooth and strong once I get out of the idle stage. My pilot mixture screws I've been starting at 2 turns out, but have been playing with them constantly trying to get it right. My main issue is that I'll crank it up, bike idles high so I start unscrewing my pilot mixture screws at about 1/8 turn at a time to richen the mixture and then it dies unexpectedly within less than 30-45 seconds of running. I gave up and set the mixture screws at 2 turns out and tried to balance the carbs, but I can't keep it running long enough... Also, before setting the mixture screws, I've been curious as to how far off I should have my overall idle adjustment backed off. I've been setting it just to the point where it barely lifts the throttle off of bottom. Is this right? I'm going to order new stock #35 pilot jets, but I'm afraid that it won't solve my issues. I'll be able to let you know once I get this starter clutch replaced... Thanks in advance for any input!

Well my bike still stumbles off idle, how about yours calebstrawn?

I got all the bottom end (starter clutch) put back together a few weeks ago and tried like hell to make my modified pilot jets work. The bike would rev strong and smooth but was still having trouble dialing in the idle mixture. I had my pilot mixture screws turned in so far they were basically closed to get it from being too rich. So I gave in and ordered new stock #35 pilot jets. I finally got a chance to put them in last night. I backed out the pilot mixture screws to 2 turns out, it was idling a little high, so backed them out another 1/8th turn and bam, purring like a kitten. :woohoo: Took it for a few test rides last night and haven't had any trouble at all. It's definitely woken up with then new jets and pod filters. Rode it to work this morning.
Jumpship, if your's is still stumbling off idle, I'd look at raising the needles a shim or two. I have mine at 2 shims up. Increasing the primary jet size effects it mostly at wide open throttle, from my understanding.