cr 125 running rich

[jwcckr]

I have a 94 CR 125 that floods the plug out in a short period of time. I am running a 50:1 mix with synthetic oil. It bogs/hesitates on take off and falls flat on top end(my sons KX100 is blowing this thing away :( ). It was only doing it slightly and gradually got worse. The engine has been rebuilt with all new seals, piston, etc.. It had this problem before the rebuild. It have tried a different carb and CDI and repacked the pipe. I dont have any ideas and was wondering if anyone could help shed some light for me. I am a auto tech for 18 years so I am very familiar with engines and electronics, but I am at a lose here. Thanks in advance for any help that is given.

John

P.S.
Could the powervalve be causing any of these symptoms? Thanks again.

 

[IndyMX]

Do a search on here for Jetting.

 

[jwcckr]

If it was jetting, could it get worse or wouldnt it just be off front the start? I know the engine requirements will change as the engine wears, but this just seemed to happen to rapidly, but then again, I am not too familiar with 2-strokes. I will do some searches and I think I have some other jets to try. Thanks.

John

 

[IndyMX]

I'd also make sure that the carb is clean, take it off and tear it down.

Clean air filter...

Check the reeds.

And check and clean the power valve.

 

[griffbones]

Are you loosing any trans oil? Could be a right side seal causing the engine to suck trans oil and foul the plug. Even a new seal can get nicked upon installation of the crank!

Does this thing foul the plug like immediately? If so, is it really black and wet? I have had a bad stator cause this before. I could put in a new plug and in like two minutes it would be fouled (black and wet). After about four plugs in 20 minutes one day, it would no longer fire at all, even with a new plug. Turned out to be the pulse coil on the stator was going bad and had finally gone open, thus I no longer had any fire at all. I know this is not the normal, but just an experience that I had on a two stroke Honda.

 

[Trashrider]

If your jetting is stock, then you are definitely running rich due to your mix ratio of 50:1. Try 32:1 and see how it runs.


Mark

 

[Moose]

Agreed.

32:1 is a good mixture on mine.

 

[griffbones]

I also agree with the last two posts. I re-read your first post and noticed that you had this problem before the re-build. Adding less oil only makes the engine run richer (more gas) and will make the plug fouling problem worse, along with less protection for your engine. Go back to 32:1 or even 40:1 and do some plug readings and go from there.
BTW keep in mind that a fresh top end will run slightly richer than an old tired top end, so this could have made an exsisting problem seem worse.