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1989 xr250 help asap!

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what engines from what years will fit(bolt right in) in this frame if and or when this one is gone? also is it possible to remove the cylinder sleeve and replace? possibly with the stock bore and piston? friend of mine says bottom was rebuilt and top was bored out by PO. BUT here's the kicker - we have no clue what size the bore is or piston is from the rebuild or who the kit was made by because the bike runs strong as hell right now and didn't want to risk taking the top off. can someone please shed some light on this for me? Is this bike a ticking time bomb?

Any answers ASAP would help! Please and Thank you!

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If it is running strong & does not make any noises I dont really think you will have anything to worry about?

As far as I know an 86-95 250R or 250L motor will bolt in, You asked if the sleeve can be removed/replaced? Sure it most certainly can but it would actually be much cheaper to find a good secondhand barrel that is around stock size & have it bored out to the first oversize if you are really worried

Just because it has been bored out does not mean it will have problems, It may only be bored out 1mm which is certainly nothing to worry about

I am going to buy a secondhand barrel for my 93 XR250R soon & have it bored out to suit a new oversize piston, Probably 280cc which is a common size to give the XR250 a bit more up & go & it will not affect the reliability if it is re-jetted/tuned & maintained as it should be anyway

Edited by XR250INOZ

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The piston dome or shaving the head or using various gasket thicknesses afftects clearance and compression.

Search this forum for comments by Dwight Rudder. He has had several bored and stroked XR's. I think 280 is the max bore.

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what engines from what years will fit(bolt right in) in this frame if and or when this one is gone? also is it possible to remove the cylinder sleeve and replace? possibly with the stock bore and piston? friend of mine says bottom was rebuilt and top was bored out by PO. BUT here's the kicker - we have no clue what size the bore is or piston is from the rebuild or who the kit was made by because the bike runs strong as hell right now and didn't want to risk taking the top off. can someone please shed some light on this for me? Is this bike a ticking time bomb?

Any answers ASAP would help! Please and Thank you!

A dirty carb jet can cause your engine to run too lean and melt your piston. Your powerplant is a complex piece of machinery and there are many factors that weigh in on reliability. A bored out 250 that is properly machined, properly set up, and properly maintained could easily go 20,000 miles. The bore itself is the least of your worries.

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thank you for the info, does the bigger bore affect valve clearance? or should they be tuned to stock manual specs?

Use the stock manual specs. I think they are .002" for intake and .003" for exhaust. Too loose = a little noisy. Tight = burned exhaust valve.

Adjust cold.

.

Edited by Baja Rambler

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As Bajarambler mentioned stock clearances, You could bore & even stroke your motor out to the max size & the valve clearances still need to be stock, Nothing changes there, Same goes if you were to buy an aftermarket camshaft, You would still set the valve clearances as the manual states

Better to have them just a little bit loose or preferably in the middle of the specified clearances in a manual & the same goes for just about any bike really

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so i guess my overall question is, is there any way for me to know if the bike was bored and all that correctly without having to strip it down? im now possibly considering buying it but like i said i cant just strip it down at my friends house...

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. . . . is there any way for me to know if the bike was bored and all that correctly without having to strip it down?

Only Superman can do this.

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