Shimming CV34 needles?

Pretty sure polkat's got an H3 with the Keihin CV-34's.

Somewhere I believe he mentioned he had a primary and a secondary jet, this would make it a dual butterfly Mikuni. This is what I mean, we are guessing here. We need the full information on the bike. What the heck, some of these carbs have 3mm needles and some 2.5mm needles. Just too many speculative variables here.

If in dead he has an H3 than he has dual butterfly dual jet Keihin carbs. He will have a heck of a time to even get jets for those. Pretty much for those carbs he has no choice BUT to go with a Dinojet kit. He needs this kit and follow these instructions.

www.dynojet.com/pdf/2102.pdf

polkat wrote:

...been considering going to pods and drilling out the back of the mufflers....

Imo, such drilling is ill-advised.

Might instead check ebay for an idea as to what the unspoiled stock exhaust system is worth, as some of these are bringing pretty good money, and perhaps enough to cover a 4>1 system, superior to a drilled stock muffler.

Good Fortune!

Patton wrote:

polkat wrote:

...been considering going to pods and drilling out the back of the mufflers....

Imo, such drilling is ill-advised.

Might instead check ebay for an idea as to what the unspoiled stock exhaust system is worth, as some of these are bringing pretty good money, and perhaps enough to cover a 4>1 system, superior to a drilled stock muffler.

Good Fortune!

That is an excellent point. He might get enough for the system to cover a header exhaust AND the Dinojet kit.

I have a 1980 KZ 740/4 with Keihin CV34 carbs, K&N pods and a Mac 4->1 exhaust. I bought it like this 7 years ago.

Original/stock jetting on these carbs for the 1980 model with airbocx and 4->2 exhaust was secondary main 125 and primary main 62.

When I bought the bike it had secondary main 135 and primary main 62. It ran just fine

A few years ago I upped the secondary main to 140 and the primary to 70. It runs even better. The Keihin jets are available from Z1Enterprises for about $2 each. They dont list the smaller primaries on their website but if you want them contact them.

Different size pilots are no longer available but it is cheap to experiment with different primary and secondary sizes. I have never needed to even consider shimming or adjusting needles or doing terrible things to slides.

According to the Haynes manual all 750 E,H & L models had the same Keihin CV34s. The N1 model also had Keihin CV34s but with very different jetting and needle. The P1 (shaft) and R1 (gpz) models had Mikuni BS34s with different jetting and needles to each other

Had the bike come with a stock airbox I probably would have left it alone but as it is it came with the pods and 4->1 and I have never had a problem.
Long may it run.
Hope this helps.

hobby shops are a good source for small brass washers to use as shims.the ones i got were .010 thick,and there were others.take calipers with you to check the thickness tho.
hope this helps someone,

leon

JR, thanks, very helpfull! And thanks to everyone else as well.

Ive run my 82 GPZ 750 with the BS34 Mikunis on it with stock jetting using an RC 4-1 pipe since it was new. I just took the idle mixture plugs out and richened the screw up a little and its run prefect ever since. The airbox is untouched. Still only has 15000 miles on it.

otakar wrote:

If in dead he has an H3 than he has dual butterfly dual jet Keihin carbs. He will have a heck of a time to even get jets for those. Pretty much for those carbs he has no choice BUT to go with a Dinojet kit. He needs this kit and follow these instructions.

www.dynojet.com/pdf/2102.pdf

Not true! I got a jet kit (very similar to dynojet's) for my 750 e3 with keihin carbs from 6 Sigma Racing. Found them on ebay and the kit is specifically for YOUR setup (mine is v&h 4-1, k&n pods, sea level, etc). Check them out if you are looking to do some performance mods.

i am doing the pod filter and v and h megaphone exhaust upgrade to gain some cheap horsepower, considering the wide array of options it would be one of the cheapest. I have a couple questions, first are the factory csr 1000 m1 vacuum carbs as bad as what i was told. the guy told me if i wanted to go performance that i should get rid of the stock vacuum carbs for some mechanical action ones. Second off the subject of carbs how much hp can i expect to gain with a vance and hines megaphone, pods and jetting.

I am running 81 CSR 1000 carbs on this 1150. They can be made to perform as well or better than 31mm smooth bores with none of the draw backs of smooth bores. Who ever told you "how bad they are" has "No idea" what they are talking about. And in my opinion should be kept away from motorcycles because he could be a danger to himself and to others. BS34s are some of the best carbs ever made, and can be made to perform any way you want them to. With a pipe, pods and jetting you could pick up somewhere around 5Hp+/-
The question is How & Where you plan on riding it. Different pipes will give you different HP at different RPM ranges. A cannister pipe like the one I have on my bike is more of a mid range pipe in comparison to a Megaphone pipe which is more of a upper RPM range pipe. Also to warn you, a megaphone is quite a bit louder and "dronier" than a cannister pipe. A cannister pipe has a crisper and "poppier" sound.