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First time jetting 2 stroke help

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So i have an unknown year yz125 it's actually on my first shifter kart which also happens to be my first 2 stroke :goofy:

 

 I know the carb is not normal or typical for a yz125 (at least I think not) it's a kehien pj38 carb. Does anyone have any suggestions of where to start the jetting for this setup? The guy I got it from had messed with jetting but couldn't get it to run right, i'm not even sure this carb engine combo is a good idea? 

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Take some pics of the engine and carburetor so we can ID which model year it's from.

 

Since carts run more sustained high rpms than typical MX track straightaways 

and likely ported for more top end power, I'm sure they're rather jetted on the rich side versus bikes.

 

Late model (at least 2006+) YZ125's have a Mikuni TMX38 carb,

typical settings are #40 pilot jet, #42-74 needle, #410 main jet.

Newer ones (13+ ?) have a longer silencer and run a #430 main jet.

Edited by mlatour

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10 hours ago, mlatour said:

Take some pics of the engine and carburetor so we can ID which model year it's from.

 

IMG_5752.JPG

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If cylinder and head are originally from the same engine, this thread would suggest it's a 1999 engine.

link: 

 

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Yeah, I knew that's what year it was, I just didn't know if that engine and carb would be an effective combo together?

However digging into the engine tonight I found a lot of modifications made from the builders of the engine/kart combo. So much so I couldn't put the original carb on any longer if I wanted to, so I guess I'll have to try to sort this one out...

Edited by xtactical

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