Problem

Ive had the fly wheel and stator off also clutch main gears from crank counter balance bearings replaced so counter balance shaft has been out carbs been cleaned twice new plug reed block out and checked.. Really can't think of alot else to do oh and the fly wheel key is in good nick.. The outer part of the flywh:cool:eel has a key way in it but doesnt sit on a key..but this is just to run the lights etc right? Other than splitting the main cases and barrel/head off ive done it all.. Ill have the head off in an hour or so when I get home ..i am fairly confident the stator went back in the same place..
 
Is the cdi the same on a 2007 250? Might be able to borrow a mates to test it.. Its a.ngk plug same as it was running for the last 6 months br8eg I think..
 
I don't know if the CDI is similar. Best of luck, I doubt anyone knows what to suggest at this point. At least try a new plug.
 
ive tried 3 different plugs now one that was in it when it stalled a brand new one and one i removed that was in full working order 6 months ago just for a fresh one.. ill have the head off when i get home and report back..
 
A loose/dirty electrical connection can happen all of a sudden and plays havoc with diagnosing running problems. I would check and clean ALL electrical connections on the bike. A loose connection is easy to spot and easy to fix, just squash the receiver to get a better fit. I know first hand how painful it is trying to diagnose these kinds of problems.

If all else fails, could you not just take it to a bike shop and have them look over it?
 
Bad news had the head off no rock in piston so barrel is coming off.. Theres a nick in the top of the piston looks like a rings failed and scored the bore a bit.. Which is shit as ive only just spent 350 quid having the barrel re plated and new wossner piston and rings not.so long back.. What a bastard .. Ill keep you updated.. What causes this?
 
So the barrel isn't to bad one little nick around a port that won't polish out.. Piston is a right off with the two rings stuck to it by means of a big slot.. Heres a question should my con rod have any play in it left and right and up an down..?
 
Rabbitist said:
So the barrel isn't to bad one little nick around a port that won't polish out.. Piston is a right off with the two rings stuck to it by means of a big slot.. Heres a question should my con rod have any play in it left and right and up an down..?
Click to expand...

Side to side a little, there is a spec somewhere for that. If it tips side to side, that is worse than lateral clearance between the crank webs. Up and down absolutely not. That usually means big end bearing has failed.
 
Rabbitist said:
thanks. i guess i know why my piston went then :( do i need to split the cases to renew big end bearing?
Click to expand...

Yes, you'll also need someone to rebuild the crank too, as its not something that should be done at home unless you know how to true(balance) it properly.
It may be worth throwing a new rod in as well, because its probably the 12yo stock item. Good news is a CR250 rod is a direct crossover and it shouldn't be too hard to find a cheap aftermarket one.
 
im a machinist by trade so guna take the crank to work and have a go.. should i replace the crank pin? what material are crank pins made from? might whip a new one up
 
scrap making a new pin ive just read they are chrome plated.. unless nimonic would do? anyone know were the cheapest place is for rod kits??? or could i re use the pin and just swap out the bearing and rod?
 
Rod kits include the pin and big end bearing. Some kits come with small end bearing, you need to confirm. I think that all CR250 rods fit starting after 1990, or something like that. I made sure that my rod was from the late 1990's/early 2000's to ensure compatibility.
 
thanks guys all this info is very much appreciated! am i right in thinking that if i press the pin on the crank somewhere near i can then bore out and hold it in soft jaws in a lathe and tap it true with a dti on the bearing journal and a hyde mallet?
 
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