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86 Carb Tuning Help Needed

1K views 2 replies 3 participants last post by  doug 
#1 ·
I'm having trouble tuning my carbs on my 86 GSXR 750. I have individual K&Ns, Yoshi pipe, and timing advancer. I installed a Factory Jet Kit with #35 pilot jet, needles set at #4 (as specified), idle screws out 3 turns, and the supplied #142 main jets. 1/8 to 1/4 throttle breaks up badly and at WOT it breaks up between 5500 to 7000 RPM. My floats are adjusted to spec. I've tried main jets from 124 to 160 and just about all the needle positions. Any suggestions? I'm considering trying the Dynojet jet kit. I noticed the instructions call for drilling out the slide lift holes with a #32 drill bit (what does that convert to in inches?), should I try that? TIA.

Rob Robinette
 
#2 ·
this is probably not going to help much, but my short-lived experience with the stock 31mm cv carbs on the 86 750's has shown that the only thing worth doing to them is throwing them into the trash.

i also could never get them to run right with individual filters, although i didn't try as many main jet combinations as you did.


the 34mm carbs from the '87 and especially the 36mm slingshots from various other suzukis (88-89 750, katana 750's, etc.) work beautifully on the '86, and are much less frustrating to tune.

try scouring your local motorcycle salvage yards, or ebay, you're bound to run into a used set for a good price.
 
#3 ·
my 86 being a cdn model has flatslides instead of cvs so my jetting info wont work but one thing I had to do to get mine to run right was set the carb sych so that the outside carbs pull more air than the inside carbs and I do have kns as well. If I sych even across the bike has a really bad flat spot of idle and a hole at around 5000 try one graduation diff or about 2 inchs of vacuum diff. Normally this mod is used with the stock airbox but find it works well with individual filters.
 
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