Jun 21, 2000
Could I trust my local machine shop to bore it out to 38. I would remove the nozzle jet, floats and all the rest to make sure they don't lose parts. How much should I expect to pay?

I'd be curious to know AJ's price for a 38 TMX.


Aug 14, 2001
I recently had a carb bored out for my kids 80. $50 including return shipping. excellent finish.

I would have done it myself in a lathe but did not know the "secret" diameter. if your interested


David Trustrum

Jan 25, 2001
Bore out what carb? We’re not physic.

Psychotic maybe. . .

I mean does your local shop bore out carbs often? Is there enough meat in this carb? If you trust them to experiment is the gamble worth the risk to you to say ok that didn’t work buy a new carb?

Why would you expect them to be that much cheaper than a tuner offering this service? Remember you are also buying experience.

Try not to remove any from the floor.


Super Power AssClown
Aug 24, 2000
Regarding carb boring, I've got to side with David. Theres a good reason why I don't offer that service, theres too much going on in there! I've seen lots of examples of carb boring from name tuners and I've got to conclude that none of them should ever connect a carb to a machine tool.
Heres the typical pitfalls;
1) A margin of .7mm must be maintained between the sides of the slide and the bore. If the bore is bigger than the slide air will bypass the venturi and make the engine run lean.
2) The bore must be consistent straight through. Many tuners offer carb boring on carbs with non-removable needle jets so they only bore each side of the carb up to the venturi. Thats useless.
3) Deburring of the slide to bore interface is critical to smooth throttle operation. AKA Stuck Throttle!
4) Deburring and finishing of the pilet circuit outlet is also critical and the height of the outlet also limits the bore size.
5) If you've ever ridden a 250cc bike with a stuck throttle you'll gladly pop the $200 for an aftermarket carb because laying on your back all summer in a body cast is kinda itchy!

Good luck, Eric


Jun 21, 2000
Thanks for the replies. That convinces me to talk to AJ about a new tmx 38. BTW the bike is a 00cr125 as said in my signature.
Top Bottom