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Discussion Starter #1
CAN SOMEBODY HELP ME TUNE MY \'91 GIX 750, PLEASE...

I have been trying to tune my '91 750...Stage three, V&H sr2 exhst, dyno jet kit...nothing seems to work. I've had the bike "professionally" tuned three times and it is OK for just long enough to get out of the shop. It still gurgles bad above 7 grand, and even worse below 6k. At one point I had 110HP, it doesn't seem like I do anymore. What's next, 1100 cams, 42mm carbs? Or will that just make it even less tuneable.
 

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Re: CAN SOMEBODY HELP ME TUNE MY \'91 GIX 750, PLEASE...

Oh dude only 110bhp?? i had a '91 rd/wht/blck got 113.8bhp w/it this is all i did to it
yosh duplex full sys
dyno jet stage 1
k&n filter
fox shock
v&h ignition advancer
braided lines
slotted and degreed cam's to yosh SS specs
yosh heat shield (carb shield)
progressive fork springs

at the time i was pulling zx750r's w/no problem and the new '92 liquid cool'ds
have you adjust the intake exaust timing on on your cam's?,you may have to fiddle around with some to get the it right.what bout dyno time to see where she's falling off?
to be honest w/you i never really heard good stuff boout v&h's exaust unless they were on yami's of that same time period,if it's just a "stumble" at 7g's and not above could be a flat spot.

prob with goin to bigger carbs(ie:42mm's) is now your settin up for just top end you'll lose ALOT of midrange and you think you got tuning probs now?

i know i got a pic somwhere of this old warhorse somewhere i'll try and post her, she was so good at laying down the beatings on other 750's of the time. i kept her for 4yrs
not once did she fail me,and i vowed never to buy the liquid cooled machines(gixxers) and went straight to a cbr900.
ya im lookin now for the pic gimme a day or so then i'll post her for ya (man she was a good horse,brings back alot of good mememories
)
 

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Re: CAN SOMEBODY HELP ME TUNE MY \'91 GIX 750, PLEASE...

I have a 91 750. Stage 3 carb kit (160 mains), Hindle stainless 4-2-1, stock 38mm carbs with single K&N's. I will install the K&N dual filters, now that Jeff has opened my eyes how to get around a fuel hose problem.

What size mains are in your carbs? Airbox or filters, how old are the filters? Cleaned them recently?

Mark
 

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Re: CAN SOMEBODY HELP ME TUNE MY \'91 GIX 750, PLEASE...

he likely has a california spec bike......a bit down on peak hp due to 36mm instead of 38mm carbs....
 

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Re: CAN SOMEBODY HELP ME TUNE MY \'91 GIX 750, PLEASE...

Yeah I do have a Cali bike. So I should get the 38milli carbs and an ignition adv?
 

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Re: CAN SOMEBODY HELP ME TUNE MY \'91 GIX 750, PLEASE...

Yeah larger carbs will help your top end, but if you're going to switch carbs you might as well look for a used set of flatslides (not CV) which should give you a good boost and better throttle response. Larger cabs, however, will make it tougher to tune at low RPM and small throttle openings, especially without an airbox.

But the real problem sounds like your jetting is off or else you've got something else fundamentally wrong. I'm not sure what you mean by "gurgles" but if it's stumbling you're probably rich or fouling plugs. If it's running good out of the shop then getting worse that sounds like fouling plugs from being too rich or burning oil or maybe an ignition problem (I've heard these bikes go through coils, though Ive never had a problem with mine). Might be badly balanced carbs too. If you don't want to play with it yourself I'd try a different shop for a good basic tune-up and try to get to a good running baseline before you start throwing money at it trying to get it faster.

For shops I've heard good things about KC Engineering and Scuderia West in SF, mixed things about Die Werkstadt (though they do have a dyno which is good), and horrible things about Golden Gate Cycles. Factory (as in the jet kit makers) is right up in San Rafael, I don't know if they actually work on bikes but they seem pretty friendly and should be able to recommend a place with a dyno who does good jetting work.

If this helps my Cali 92 750 has a full exhaust, K&N in the airbox, and an ignition advancer. It's got a Dynojet Stage 1 kit in, with 35 pilot jets, the dynojet needle, and the 124 main jets.

Matt
 
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