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Discussion Starter #1
Looking for some advise on keeping my 87 250r from overheating. It has a stroker piston with a cool head. I am now going thru a 2nd piston due to over heating and blowing a small hole on the top of the piston. I went thru the water pump and made sure it was not obstructed and have changed my plug to a BR9ES. I was considing a PWR radiator, but I was also looking around the internet too see if anyone makes a hy-flow impeller. Any advise!!!!!
 

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Are you sure its not lean or having detonation?? My friend had a 250r with very similar problems, his jetting was very lean and had a partially clogged radiator. Check your jetting first and then correct me if I'm wrong, but its when you get a hole in the piston is a clear sign of detonation??
 

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could it be a jetting /lean issue ..hows the plug look ?

what shape is radiator in? ..all fins clean clear?
 

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Yeah, detonation can do crazy and destructive things.
 

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Holy crap a hole in the piston! Ya man I would check the jetting and octane rateing/psi in your cylinder.. Overheating usely melts rings and welds the piston to the bore, or strees cracks rods, frys bearings, etc..
 

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a hole in the center of the piston is usually from detonation. Lean/overheating usually frys the exaust port size of the piston.
 

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sounds lean to me
 

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what size dome are you running in the cool head?
 

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what octane are you running also?
 

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Discussion Starter #10
Thanks to all!! Im not sure of the dome size, but the radiator is the original radiator and it has no fin damage, but could need wroughting out to assure that there is no partial clogging. Denation sounds more like the issue!!! I guess when I rebulid it again I will up my jetting and rich-in the gas mix up. My octane rating is 101, I only run racing fuel which is still avalible at my local gas station here in Las Vegas!!! Im using a 32:1 mixer with MAXIMA 2stroke oil. My compression at the last rebuild was up to 215psi!!!! I get disappionted, but I cant get rid of my 250R its a timeless classic. Any Jetting advise?? I moved up to a 38mm carb way before the 1st engine rebuild.
 

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jetting and richening your fuel oil ratio wont fix your detonation issue. i think 215psi is probably too high for 101 octane fuel. if i was going to run 215 psi i would make sure to run a high quality leaded race fuel 108+ octane. if you dont want to spend the money for race gas, swap in a larger dome if you have that option, or use a thicker head gasket.
 

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You better figure out your jetting before you run that thing again. A lean condition can cause pre-ignition which does crazy things like detonation does. As suggested previously, you may want to run 108+ octane or lower the compression for 100 octane.
 

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Take you a bright light of some kind, hold it between the radiator & the engine & then get in front & try to look through the fins, see if its clogged up.
You have fine silt sand out where you are & all it takes is a little moisture to cause the silt to stick in between the fins then it keeps happening & you get a build up hendering air flow.
The radiator is the last thing I wash when cleaning the bike.
Sence the bike is already clean, when I presure wash the radiator, I can tell if theres a build up by looking at the water flowing on the ground, I look for dirt, in our case though here on the east coast I check to see if its red from red mud.
Neil
 
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