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View Full Version : Honda 250x - 12:1 piston alright?



TheRealFatShady
10-09-2010, 12:00 AM
This is going to sound nuts...I know.

I need a 250x (87-92) piston. I looked online, then checked eBay for awhile. The only pistons that are over the stock (74mm) size are 12:1. Even the stock ones looked like mostly Wiseco 12:1 kits on eBay.

I CANNOT find one that is maybe 11:1, or 10.25:1. Maybe I can get one if I call some places, but I've never heard of only seeing high comp. pistons commonly available. I thought only full one racing machines ran 12:1 - I want to use pump gas.

Is it OK to run this with a mostly stock bike? I mean stock valve springs, cam, non hard faced rockers. I do have a cobra exhaust + aftermarket header, and maybe jet kit and air filter.

I've also searched, and at least 2 other people on this site claim it works fine their bike. but recommend exhaust + jet kit. One bike stock, one has a cam, carb, exhaust, etc. No valve work.

http://www.hondaatvforums.net/forums/performance-modifications/4091-87-250x-12-1-piston-all-else-stock.html

Thoughts?

EDIT - I guess I can use a 300ex piston kit, it's interchangeable but lower compressing rating. Apparently the 250x engine runs better than the EX, so peope often use the 250 pistons in the 300. Most are 11:1. That should be better?

If Namura pistons work well, I can get that + gaskets for around $100 shipped! Lots cheaper than the 12:1 250x pistons. Even wiseco's are about $40 less for the 300.

falloutboy
10-09-2010, 04:34 AM
ok so i looks like I finally threw out all my old receipts for the 250x I used to have, but I went thru exactly your problem. I needed to bore my cylinder but wanted to run pump gas. I'm pretty sure it was a Pro X brand

What I came up with was a 1st bore (74.25), standard compression piston. I got it from an independent parts/service guy in Reedsport, Oregon. The place is called

#1 Stop Sports Shop
2150 Winchester Ave
Reedsport, OR 97467-1153

phone: (541) 271-0970

They are pretty knowledgeable people. With any luck you'll talk to Pat (the owner) he really knows his stuff. If you aren't able to make the long distance call, let me know and I could probably call the and get the part number.