little miss at high RPM's 95YZ125

[fredrader]

Hi All and merry christmas..I was riding my 95YZ125 today and I stretched it out thru all the gears and it had a little miss in the higher gears..The engine was warmed up but the air temp was like 40deg..I tried it several times and it seemed to do it every time..It didn't do it in 1st 2nd 3rd or 4th but it did it in 5th and 6th..I checked the plug and it is dry and brown (BR8ES) and the book calls for a BR9EG..I checked the compression and it was a little over 150lbs..It has a PhatHead Racing Head with the next step up from stock dome in it..I don't know what the stock compression is supposed to be let alone with the phathead on it..Any ideas? :think:

 

[snb73]

Did it do this in warmer weather? Or did it start this just as it got colder. Try richening up the main a few steps. That shouls solve your problem. And install the recommended plug first.

Good luck, Steve.

 

[fredrader]

I didn't notice it doing it when the weather was warmer..I don't know why the previous owner used the BR8ES instead of the BR9EG but it really runs great with the plug that is in it..
I need to tear into the carb so I know how to work on it anyhow..I have never had it apart since I got it,for that matter I haven't had any of the carbs apart on any of my bikes..I was curious though about the compression,wondering what the compression is on a stock fresh 95YZ125 is supposed to be..

 

[fredrader]

Well I tore into it today and removed the carb(After removing the seat,side panels,radiator guards and fuel tank :pissed: )and all I did was remove the top of the carb and pulled out the jet needle and dropped the clip from the 2nd position from the top to the 3rd from the top and re installed the carb(And all the plastic)..It fired up 1st kick and I let it warm up and took it for a few hard passes thru all 6 gears wide open and it didn't miss at all.. :) .The temp here is 37deg...I guess that fixed it.I have never had the carb off any of my bikes and was kinda hesitant about tearing into it but all went well thanks to all the great people passing on lots of great info on this site..Thanks