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yzf750r questions and tuning.

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5.7K views 4 replies 3 participants last post by  YZFTX7500  
#1 ·
Hey so I got a yzf750r about a year ago swapped a new engine into it and been trying to tune the carbs and figuring out the turn signal wiring since the dummy before me chopped all the wiring up and fuses get expensive. So a few questions.

As far as jet kits go I've heard good and bad about dynojet kits. Any horror stories about them?

Also when im trying to tune the carbs which way do I turn the screw to richen or lean the mix?

Do I absolutely have to have the exup and airbox attached to get an accurate tune?

What about the float levels? What is the gap on that?
it seems the Haynes manual is better used as rolling papers than mechanical specs

And please any other tips or tricks you may have I'd love to hear em

Cheers
zedane
 
#3 ·
How do you know the Exup moves? Odds are it does not. In that case start looking for a header or fabricate a cover plate after you remove the Exup valve. Do not remove the servo or disconnect the wires. find a slip on and sell me the stock pipe. Dyno kits are a pain in the ass unless you know carbs. Some say they do but a true "tuner" knows carbs. A kit, no valve and an after market pipe runs like shit without the proper tune. No kit, no valve and after market pipe runs good after 5K RPM. who cares about anything under 5K.
 
#4 ·
Well I know for a fact the valve moves because I can turn it with my hand but one of the exup cables frayed so my question really was can I start tuning it or should I wait until the new cable gets here? But I want it to run well under 5k so I can let it warm up on its own. I've got a Vance and Hines ssr2 plugged onto it and if I put brand new plugs in it, it runs like champ then pull the plugs and they are black I know its running rich. I've tried screwing the mix screw in and out and it gets a little better at 1 turn out from seated so im thinking that's where the airbox and exup come into play. Im assuming the resistances and restrictions are what lean it out a bit more. I also installed the d ynojet stage one with the .122 jet which I believe is stock. Any advice anyone?
 
#5 ·
I don't think the Haynes manual is even good enough for rolling papers, "in" is lean and "out" is rich for the fuel screws, the most likely reason for your plugs turning black is the float level, these bikes don't like the wrong float height , 14-15mm is the setting, visit factory pro`s website, it has some great info on setting them, the special tool works great also. the nozzels also wear on these bikes and causes rich conditions as well, along with the needles , wait until you replace the exup cable before you tune it.