Original Piston 250R locks up, now what?

[Blown 331]

Yep, I've had it for about 6 weeks now, just got my ESR exhaust on it a few days ago and it's locked up. I was riding down the road, probably about 50mph and I heard some weird noise so I pulled the clutch and it died. I coasted to a stop and it wouldn't kick. There was also a small about of antifreeze around the head gasket.
I pulled the cylinder and both piston skirts are broken off. The crank appears to be ok but wont rotate from the piston in the lower end. I pulled the entire motor and am in the process of splitting the case.

Now for the big question. What should I do now? I have a TRX450R and I want the 250R to smoke it. I want to spend about $600 to $900 on the motor, so that doesn't cound a new carb, I may be able to stretch that a little.
The crank will be out so I don't know if I should stroke it while I'm there or what. What about a long rod and spacer plate? I also don't know if I should just get a .020 over Wiesco or just get a big bore cylinder. Or maybe look for a whole built motor on ebay.

I need some suggestions here, I'm kinda new to 250R's.

[83185s]

hell id bang that piston out and bore the cylinder and get a bigger piston..then rejet and new top end gasket kit and u should be good to go

[Blown 331]

hell id bang that piston out and bore the cylinder and get a bigger piston..then rejet and new top end gasket kit and u should be good to go

Yeah, the piston is out of the cylinder. The cylinder looks totally fine so I guess at a minimum I could have the clyinder ported, bore it .020 and get a 12 to 1 piston. And I have access to a 36mm flat slide but I don't think that's gonna be enough to take the 450R. Anyone know where I can sent the piston to get it bored, ported and timing ported or what ever that is. lol.

[Blown 331]

I think I'm gonna buy a power valve motor off ebay.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=4506666211&fromMakeTrack=true

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=4506397124&category=43981

[x.system]

Personally I would go through your bottom end, then go with an ESR ported cylinder. Size would be determined with what you want this motor to do and how you plan to use it. You never know what your going to get when you buy a different motor, at least if you start from your bottom end you will know what you have. I would contact esr and ask them, give them your price range and I'm sure they will be able to work with you. I have paul turner cylinders and there is no comparison to stock but my next cylinder will be an ESR.

[250rAL]

Did you rejet with the new pipe? Just a coincidence that it siezed shortly after you got it?

[Blown 331]

Did you rejet with the new pipe? Just a coincidence that it siezed shortly after you got it?

I didn't rejet it but the piston didn't lock up in the cylinder. Then engine locked because the piston skirt broke off (probably because of too much clearance) and fell into the lower end and locked the crank. I think the crank is ok though, I should have it out tomorrow.
I guess I will give ESR a call and see what they have to say. Those power valve motors on ebay are looking pretty nice though.

Oh yeah what reeds should I get.

I just ride it for fun, some trails some road riding. If had to pick a purpose to build the engine for I would say drag racing.

[x.system]

I run boyesen rad valve but if you are going to build a motor I would use what your builder recommends for best performance. They will be able to put together a complete package and they know what works best with their motors. If you plan to drag race you may want to do some research on those power valve motors, from what I have read they are more suited for mx, but that is based on the trx. Being that you want to put one in a trike may be totally different and it may be what you want. Ask Red Rider, he's got a power valve in his trike, he could probably tell you what to expect.

[83185s]

so its just the piston thats f'ed? thats not too bad..id still rejet and since trailprotrailpro into the motor get it bored..and maybe ported and polished

[Blown 331]

Here is a brand new ESR 5mm stroker crank. What if I use this crank? Can it be used with a stock style piston or does it need to be used with a special stroker piston?

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=4507030628&category=43981

[KASEY]

if your skirts broke off ,, it probably had piston slap anyway,, that is usually what does it. as far as beating a 450r that shouldn't take a whole lot of work, A 310 KIT WOULD DO JUST FINE , don't listen to most of these half baked ideas,,, talk to the engine builder,, they do it for a living. you already have a ESR pipe ,so to avoid buying a new pipe ask them what can be done to your motor with the pipe you already have,,, you can build enough power without giong to a stroker crank, which will use a special piston ,,, also there is no such thing as a 12 to 1 piston for a 2 stroke ,,compression is determined by dome volume in the head ,,, good luck

[Derrick Adams]

I wouldn't think you would need much more than you have to run with the 450R anyhow. My Z seems to keep up just fine with them and I just have a pipe and set of reeds. I seriously doubt you would need much more than a 38mm carb and performance reeds to get the job done. But, you know what they say "Too much is never enough"

[smokinwrench]

You said drag racing.

I would send my cylinder to sandtrix. He is one of the best there is for porting a 250r. He has very reasonable prices also. Goto planetsand to get ahold of him. CHAINSAW has had him port a couple motors he might also have his phone number.