Jump to content
Sign in to follow this  

Are there long lasting pistons for the 250?

Recommended Posts

Are there any aftermarket pistons for the 250 that extend the time between rebuilds? I'm not looking for more power in my bike nor do I care if I loose a little power. I am looking for a piston that I can run In my 250 that will last for a few years without having to worry about rebuilding it. Maybe someone makes a skirted piston for it or something. Does such a thing exist or do I have to continue rebuiling it every year?

Share this post

Link to post
Share on other sites

No there aren't... But aftermarket forged pistons, ie. JE, CP, Wiseco are supposed to be a third stronger than stock... So Yes you will still need to rebuild every year.

Where the aftermarket pistons are nice is, I usually tear down the motor every 30 hrs for performance reasons... I measure the OD of the piston and then if it is above the service limit considerably I just re ring to restore performance and ride again. if it is below the service limit, or on it/close to, I replace the piston, rings, wrist pin and clips.

The benefit of the aftermarket one would be you could potentially get more re -ringings out of it.

Share this post

Link to post
Share on other sites

Do you have to rejet carb if you put in high comp piston????

Share this post

Link to post
Share on other sites

Stock 04-05 was 12.5:1

Stock 06-07 was 12.9:1

Stock 08 was 13.1:1

The highest comp rato that you can run on pump gas is the 13.5:1 pistons, I like the JE pistons, they are $150 at the TT store.

But the highest comp ratio that is avaliable would be one of Ron Hamps JE 14.5:1 pistons, they need to be run on race gas...

Yes, Procircuit pistons are JE pistons. I have personally seen the PC pistons, and on the bottom of it, it was stamped JE, with a Part no. So save your $'s and get a JE, they are 100 less than PC.

Just wanted to chime into this thread. Could someone tell me what the stock piston compression is for an 05 crf250 and what the highest comp ratio you can get, Also does je pistons have anythingto do with pro circuit?


Share this post

Link to post
Share on other sites

Boosting the compression like that won't hurt my reliability? Wouldn't it be more reliable if I got one of the new pistons you are telling me but leave it at the factory compression? If you up your compression do you need to put in stronger studs?

Thanks for all the feedback guys :applause:

Share this post

Link to post
Share on other sites

I haven't found a long lasting piston like the yamaha's run... but the JE 13.5 seems to be a longer lasting piston.

Thumper racing was selling pistons with a big skirts for their BB kits... that was about the closest to long life. But no 3 ring pistons that I know of.

  • Like 1

Share this post

Link to post
Share on other sites

The reason the stock Yami's pistons run longer is because they are double ring design.


Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

  • Similar Content

    • By Callum Hunter
      I'm quite new to the moto scene and I've got a '09 CRF250R in need of what I believe is a top end rebuild. I've never gotten a rebuild before so I'm unfamiliar with the process and the steps to take in getting this done in a safe and efficient manner. I was wondering if anyone knew of any reputable shops in or near Vancouver, Canada (where I live) that could look at my bike and help me out with my situation. About 6 months ago I got an inspection on the bike and the shop told me that my cam bearings had "spun in their journals", requiring the installation of a new cam along with the rebuild. I haven't had anything done to the bike since the inspection so the motor is still in this state. She's running but I'm afraid that the motor is a ticking time bomb and would like a shop to take a look at it, let me know what needs to be replaced and get the rebuild done without me worrying about getting taken advantage of. I'm currently out of the country in school but have plans to get this done once I'm back. Any tips, recommendations, or help would be greatly appreciated!
    • By Kadensmith44
      I’m wanting to powder coat my bike but it’s all new to me. I’ve got a powder coater picked out that I’ve heard is good for what I’m doing. I’m not 100% what kind of sand blaster I need and what kind of media. I have also heard you can’t cook in the oven after you’ve baked your parts is that true?
    • By luke8500
      Hi all, 
      I have a 2004 honda crf250r and it wont start hot at all. The motor was just rebuilt with a new cylinder and piston. The valves were just adjusted. It will start cold in 1 or 2 kicks with choke but as soon as it gets hot it wont start. If you bump start it the motor will just turn over without starting.  sometimes it will start. It runs great until you shut it off.  im thinking its either a fuel issue or an electrical issue. Any help would be greatly appreciated. 
    • By SandSoldier
      Hello! This listing is for my 2007 Honda CRF250R dirt bike. Last winter I spun the rod bearing and just recently finished rebuilding it. Selling to fund new bike. I am currently the second owner.

      Current registration valid until 2020, pink slip in hand.

      Fresh parts:
      -top end kit: Wiseco; forged, moly skirt coated, 12.9:1 comp ratio (new wrist pin, gaskets, etc)
      -cylinder: new OEM
      -bottom end kit: Wiseco; (new bearings, seals, etc)
      -oil pump: new OEM
      -head studs & nuts: new OEM

      -fresh oil and filter
      -all tolerances checked in top end
      -valves adjusted
      -carb adjusted

      *rebuild was done by my dad (master tech at CAT) and I (4th year mechanical engineering student)
      *has maybe 15 minutes on new parts, IT HAS NOT BEEN PROPERLY BROKEN IN YET
      *I have email receipts, pics of rebuild, and old parts as proof of rebuild, just ask and I'll show em off

      Other parts:
      -90% tread on front and rear tires
      -excell takasago front wheel
      -custom aluminum skid plate
      -wrap around hand guards
      -spark arrestor

      Feel free to ask for any more specifics or pictures!


    • By Matt Ray
      Okay so the title is a little vague. 
      So it was having trouble idling and even starting when I first bought it about a month ago for $2k. 
      So I did a rough clean of carb, looked up on YouTube, Forums, Etc on how to do it. I only cleaned jets with carb cleaner and sprayed around the float bowl area and such, so not too extensive.
      Did that and I took it out to a park, It would start up right away mostly, few kicks sometimes, but when I got it started, I had to keep the choke on. Right when I was ready to go fast and go up to 3rd and 4th gear I'd switch it off and it would work fine and sound fine and everything, but when I slowed back down and coasted around 1st gear i'd pop it back out again because it sounded like it was going to do. I have some videos if people would like me to link to them.
      So after that I decided to take it apart and replace spark plug with OEM NGK R0409B-8, replace main jet from a old 170 to a new 170, replaced pilot jet from a old 40 to a new 42, and kept starter jet the same just made sure that wasn't clogged, ordered a new adjustable fuel screw and used that.
      and it was still having a little bit of problems! I just started up today and the day before today. It would run only with choke on, if i twisted throttle in neutral it sounded pretty good, no gun shot noises or anything, pretty smooth. 
      If I tried to take choke off it would die immediately. So I started it back up again, took around 6 kicks.. So again with choke on it sounded like it was starting to lose power and RPM's would drop so I'd twist throttle a few times and it would stay idling.. then after a small amount of time, start to sound like its about to die again... so I would rev it up again, and repeat..
      Fuel line isn't clogged, flows fine.
      I tried fuel screw everywhere between 1 and 2 turns out..
      I checked valve clearances, and I'm no expert but from the videos I watched the slipped underneath intake and exhaust with only minor force.
      So I'm lost.. 
      Maybe float bowl is messed up? Should I just do a COMPLETE carb rebuild from videos I've seen on youtube, like this one -> https://www.youtube.com/watch?v=3AXb9UprT30? Or what? 
      It's getting annoying taking it apart all the time, I jsut want it to start up quickly and run well!!
      Thank you!
      Austin, TX, Elevation 600ft, where I ride its around 900ft