Sup guys,

I recently rebuilt my 86' CR125R. She's overbored to 56mm. I rebuilt the card and put new jets in it. Standard jet is #152 and they go up in increments of 2 or 3 (not sure if it's the same for other machines never had to rebuild before). I bought the next two sizes up 154 an and 156. That said I need to upgrade my needle too, I'm looking at the service manual for my bike says there are 2 needles one with an O.D of 2.725 and the other 2.658. The 2.725 is "leaner only at 1/8 to 1/4 throttle and the 2.658 is richer at 1/8 to 1/4 throttle as opposed to the stock needle. Which jet and which needle do I go with?

I had the stock jet and stock needle in there and she was overheating like crazy. Assuming she's not getting enough fuel and was burning it off way to quick. I noticed a significant difference in trying to start her after she was hot. I put a bigger jet in but she pisses fuel out the bottom of the carb, I'm assuming bc the stock needle is too thin for the new jet. Any help is appreciated!

Cheers!
Mike

 

The carb leaking fuel has nothing to do with the jets. Your float needle is stuck or leaking. This often happens after a rebuild, not sure if grit gets in when you remove and re-fit the pipe or if disturbing the tank causes sediment to float back into the fuel. Anyway, if you are lucky, you can turn off the tap, run until it uses the fuel in the carb, turn on the tap, the flush of new fuel cleans the float needle and everything is right again. If that doesn't work, take the float out, clean or change the float needle, blow the seat with compressed air and try again.

 

So it turns out I actually have a #162 jet in my carb. Forgot that I used a correction factor of 1.07. I found a guide online that says I need to increase the needle by 2 sizes and put the clip one rung lower than standard. Hopefully this will fix the problem and give me a starting point for fine tuning it based on what my spark plug looks like.

Any other reasons you guys could think of that may cause my bike to over heat and have problems starting when hot that I may be overlooking?