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2003 RM 250 Cylinder replate, sleeve, or bore


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Today my 03 RM 250 started making a rattling noise during a hare scramble and by the second lap the motor bogged out and I was done. It has almost no compression so I'm assuming the ring and piston came apart and the cylinder is probably scared too. Anyways what are my options from what I understand its a nikasil cylinder so it cant be bored or honed its I can either have it replated or a new sleeve pressed in whats the cheapest route. btw I change my top end every 6 to 8 months and inspect everything so I guess I just had some bad luck this weekend 

 

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You can do either. 

A plated cylinder can be bored but it will need to be replated. The nikasil can also be honed but only to put back a cross hatch. 

With a sleeve you can take the cylinder bore size back to standard and then oversize and increase pistons as the bore wears. It would all depend on if you want to hold onto the bike for a few more years in my opinion.

There are pos and cons for both. If your cylinder is too far damaged then you might want to consider a new cylinder from Partzilla or the likes. 

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Replate.  It's more expensive but it will last longer than a sleeve.  And do yourself a favor and save the receipt, it'll be a good bargaining chip if you decide to sell. 

 

Also, if you change a piston every 6 to 8 months and still manage to blow a top end something isn't right.  Well, it's possible that your really fast and like to wring it out.  Personally I'd consider using a Wiesco piston for the next rebuild (forged piston is tougher than the OEM), and also look into the quality of fuel and pre-mix ratio that your using.  Please keep in mind that fuel type and pre-mix recommendations are all over the map, and the arguments will get heated.  That said, if you are running stock compression and ports then pump premium mixed with a good name brand oil (not WalMart weed wacker oil) you should be able to mix it from 20:1 to 60:1 and be safe. 

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My guess, without seeing it, is with the deep sand and cooler temps, you were detonating. Were you running good old Cali pump gas?

Exactly I know better too just was trying to be cheap and now look where im at. the piston dome was white around the edges and the front ring melted anyways its already sent off for a cylinder replate exchange hopefully it gets here fast 

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