New guy needs carb help: where to start?

[DaRooster]

I've read all kinds of info on tuning a two-stroke carb. I'll give you a little rundown of what's happening. I have a '01 CR125 that I bought from a guy. He stated that the tuning was currently set up rich. He also used Bel-ray MC1 oil in his mixture (50:1). A week ago I rode around for two hours and it ran fine. Temperature was 45 degrees and dry. Today I rode and ran totally different. Temperature was 71 degrees and dry. Smoked like crazy, misfired and/or popped from 1/4 to 3/4 throttle. Pulled the plug and was dark/brown and soaked. I have little to no mechanical background but am learning fast. Where should I start? Air adjust screw, jet needle adjustment or run a 32:1 mix? Just so you know I am running a TMK carb. Any help would be awesome. Thanks to all who reply. I plan on tinkering around with it Saturday so I can ride on Sunday.

Thanks,
Chad

 

[TimberPig]

Have you read the sticky "jetting links". It contains a couple good sources, that should help you get this done, without the need to repeat them here.

 

[oldfrt613]

I would start by running 32:1. If you prefer Bel Ray oil the HR1 is the one to use at this ratio. I don't know about the other guys out there, but 50:1 is for chain saws - I don't even run my outboard at 50:1. This in itself may clean up your jetting. If not, start with the pilot circuit at part throttle settings. Then move to the needle settings for 1/4-3/4 throttle settings. Then move to the main circuit. I usually like to make my needle and main setting while pulling a grade so I'm not too lean in high load situations like sand loam or big uphills.

Hope this helps !

 

[DaRooster]

Thanks Timberpig, I have read a couple good articles since I have posted and will try them on Saturday. Is changing the clip on the jet needle something a new guy could do? Any special tools needed. As far as the links on carb setup goes, the articles are full of great info. :cool: Hope to be tearing it up this weekend. Thanks.

Thanks,
Chad

 

[FruDaddy]

Is changing the clip on the jet needle something a new guy could do? Any special tools needed.

It is something anybody can do, a very small screwdriver and needle nose pliars would be helpful. Be careful not to lose the e-clip, it is only about 1/4 inch diameter. And pay attention to how it all comes apart, it goes back together the same way.