2003 cr250r jetting help

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9/12/2018 8:01 AM

Forgive the newbie here. I've searched a bit and am not a mechanic so a bit overwhelmed.

I purchased a 2003 CR250r recently. The bike is in fantastic shape but doesnt' run well. Spitting , sputtering, no power. I took it to a mechanic. His abilities are limited obviously. He checked and replaced all fluids, cleaned, adjusted power valve. checked compression, changed plug etc etc. Everything except the source of the problem.
I mentioned the jetting. He found the jets are not close to factory settings. It has the stock Mikuni with a V Force 3 reed unit. FMF pipe and silencer.

I ordered a JD jetting kit. Can someone guide me so I can tell mechanic where to start? Yes I'm going to find a new mechanic but he's the best I have for the moment.

I live in south florida so it's hot and muggy here now. The coldest temps ever are in high 40s and that's rare.

Thanks for any advice. It feels good to be back.



9/12/2018 8:03 AM

I used to live in SC when I last rode and raced so I had lots of places to get help.


9/13/2018 11:59 AM
Edited Date/Time: 9/13/2018 12:01 PM

The Mikuni TMX will do that no matter what jets are in it unless either the float height is set perfectly or a NLA gasket isn't leaking.

If you're determined to keep the TMX then the tool to screw in the float bowl to see the fuel level is worth buying. The other side of the coin is fitting a Keihin PWK. Buying a new PWK is cheaper than rebuilding the TMX plus money back from selling it. There's plenty on the net about this swap and your mechanic should be able to do a quick Google search and learn about it.


9/13/2018 2:35 PM

Float needs to be set/checked... JD kit will be a good addition and just follow the directions. Pretty clear. Worst case you go Keihin.


vomiting equals disqualification.

9/13/2018 2:46 PM

Save yourself the trouble and buy the Keihin from JD. I had an 02 cr250 with the stock mikuni on it and I would have to adjust/change the jets every single weekend I rode if the weather changed more than a few degrees. When it was jetted right the thing would rip, but it was a lot of work each weekend to get it right. The JD kit was about $75 for my bike, and the keihin with the JD kit installed was about $240. It was the best mod I ever did to that bike


9/13/2018 3:42 PM
Edited Date/Time: 9/13/2018 3:43 PM

You guys get that he already ordered the JD kit right? Amazing that anybody could ride these back then according to the internet.

Is the air filter clean too?


vomiting equals disqualification.

9/14/2018 8:06 AM

So I picked it up this morning. Test ride was good. But it ran so horribly before, it's like gold now.

I'm not sure what he did but he toyed around with the JD kit and did test rides until it ran the best.

Thanks for all the advice.

I posted my dilemma elsewhere and the consensus is to get the Keihin. I'm going to the track in Miami sunday morning. I want to ride a bit before I spend any more coin. Probably end up with the Keihin.


9/14/2018 1:19 PM

If it is like gold, save your money for tires and oil.


vomiting equals disqualification.