Carb tuning

Hi guys!

I'm riding a 1981 Kz750 LTD 4 strokes. Just finish cleaning the carbs and tuning them. The bike is idling fine. When in first gear it automatically dies when I pass 2500 rpm (no throttle response what so ever). Before changing the jets it was running quite well. So here's what I'm running in the carbs:

-137.5-k main jets in cylinders #1 and #4
-140-k main jets in cylinders #2 and #3
-62-k pilote jets in all 4 cylinders
-Lowered de needles by one spacer

Just so you know, I tune the carbs cause I'm running JBS pods filter and my exhaust are empty inside. My first thought is that I might be running too rich and I'm flooding the carbs, if so what should I change? Main jets? Pilot jets? Which size I should I get and where to find them online?

Thank you for any advice!

Ethan B.

DynoJet jet kit.


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Thank you!

According to their website, I should be running either 126 or 130. Just check my plugs and they are completely toasted... Think I just found out my issue.

Ethan B

DynoJet uses adifferent number scale and you will need more than the main jet.
Buy the kit it will save you from the aggravation. 


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wrote:

Buy the kit it will save you from the aggravation. 


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This, plus install a baffle in the pipe.  Open pipes are annoying as F**K

Looks waaay too rich.
That black sooty carbon is conductive, and will cause all sorts of rough runnjng problems.

Carbon deposits can be burned off by butane or propane blow-torch, heating the electrode end to a dull red and letting it cool. Resist the urge to use a wire brush. 
If you have access to one, a spark-plug sand-blast cleaner will work.

Dynojet have a nice detailed explanation of how  to diagnose rich or lean running. I'll search for it and post it here...

H.

I wonder if the baffle exhaust coloration is a good indicator of carb jetting, and spark
plug condition.

 

 That'll work as long as it don't back fire and suck it back in. 
​​​​You might want to think about a tie strap to stop that happening and you may experience slightly retarded ignition.