34mm CV 1170cc Lawson main jets?

Thinking in advance here, but I'd appreciate a few guesses at what I might start with here on the carb jetting.

Bike is an'83 ELR z1000R R2. Carbs are 34mm Mikuni CV, will have decent Ramair or APE pods. Vintage competition baffle kerker, GPz11 B motor, zx1100 head with 300 degree J3 cams.

I know a set of flatslides and hotter cams with further head work is the way to go for big bhp , but for me the bike was arm-wrenching fast even on 1098cc anyway. The only reason for the rebore was the 2 stroke like appetite for oil. A crazy fast bike - what sort of headcase would spend all their redundancy pay on one of those :laugh:

The bike was all dialed in nice but the original carbs went awol so I need to start from scratch on the jetting. All opinions and help appreciated.

The carbs are from a tuned GSX1100 , so I'm expecting to have to make some changes. I'd prefer to go for the main jet and needle height/profile before buying a dynojet kit.

c'mon guys

ok, the gsx1100 bit may have been a red herring as the carbs definitely have the vacuum takes offs?, so I guess kawasaki carbs going onto a suzuki gsx and basck to my kawasaki again.

I notice the z1100R had different main jets for the inner and outer cylinders, also gsx1100 spec different intake vacuums to 'balance' carbs...what is best here?

Carbs wearing what seems z1000J3 jetting and needles, 120 mains. would 135 to 140 be a start?

Does anybody know if Kano's elr site is still around? I bet he would have some ideas

Without running it, how could you know? I found out with my 33's Suzuki and Honda ran a different slide cutaway. 2.0 instead of 1.5 for the KZ 1000. I know there not the same but there has to be a reason. I was stuck with trial and error.
Steve

you have a very long road ahead of you ! with the time and money you are going to spend on the incorrect carbs save and buy a set of flatslides.

Yup

PLUMMEN wrote: Does anybody know if Kano's elr site is still around? I bet he would have some ideas

[Excellent pornographic memory.] :lol:

May find some helpful info from the topics and posts shown in this link:

kzrider.com/forum/search?query=BS34&sear...te=all&childforums=1

Good Fortune!

Thanks for that. I though 135-140 as I seem to remember it had 135 mains before, although googling on the subject it seems nearer to 140 plus might be a good start.

Looking closer it seems the carbs are probably originally z1000J before going onto a GSX.

If I can get it back to how it was; arm-wrenching rpm power but also tractable and responsive for riding slow around town I'll be well happy. The 4-1 supertrapp and pod filter set up previously worked very nicely, although it was heavy fuel consumption.

Tyrell Corp wrote: c'mon guys

ok, the gsx1100 bit may have been a red herring as the carbs definitely have the vacuum takes offs?, so I guess kawasaki carbs going onto a suzuki gsx and basck to my kawasaki again.

I notice the z1100R had different main jets for the inner and outer cylinders, also gsx1100 spec different intake vacuums to 'balance' carbs...what is best here?

Carbs wearing what seems z1000J3 jetting and needles, 120 mains. would 135 to 140 be a start?

Am I to understand the carbs came off another bike and the jets are different inner and outer? If so, that might be to compensate for problems with the old engine. What do your plugs look like on 1/4-2/3? They should tell you which direction to go. The mains can have a slight influnce on the low end masking low speed issues. That's the problem. Jumping to the mains is an error. Start with the pilot system first, then go from there.
Steve

No jets were matched, although I read somewhere the z1100R had 135/140 main jet: richer on the (hotter) inner cylinders. Bike is restoration project currently awaiting the block boring.

I suppose by definition, setting up a GPz1100 motor for carbs will always be a shot in the dark without any factory settings as a baseline.

I was always under the impression that carb tuning should be top down, is WOT main jet first, then, needle, then pilot and airscrew. ???