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01' CR250R Compression 185 psi

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Checked my Compression on a "never been apart engine" and compression still pumping 185 psi. I was going to change the rings but probably not now. Do you know what a new piston and ring would read?

Thanks

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rings are the least of your worries on an original cast piston. the stock cast art piston is known to crack on the intake side. i caught mine on my 2000 just in time.

anyways, i have not seen honda provide a compression spec for testing. i think testing compression on a 2 stroke might not be the most accurate test due to the mixture of fuel/oil entering the combustion chamber and helping seal the rings. i dont know if this is accurate, but thats how you test for bad rings on a 4 stroke, so the same should hold true.

if it was me, id put a new top end in, buy an hour meter and go off that instead.

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just ride it and check for any suspects every 10 hours. gets worst= rebuild.

no offense but how can he check for a skirt that's about to shatter without taking it apart? bikes going on 11 years old with a stock piston. $150 top end kit now, or potentially a cylinder replating, top end, case splitting, bottom end later. the bikes not gonna run worse when the skirts about to break off, its just gonna come apart within a split second.

easy decision from my side of the fence.

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Rebuild it and be happy the previous owner kept good care of the air filter. As stated elsewhere, the OEM piston WILL crack if run to long. No advanced warning (noise, performance or loss of cranking compression) either.

FWIW, a stock, healthy 250 2T with proper piston-cylinder clearance can push over 200 PSI.

I take a compression reading after break-in, then use future compression readings as a baseline and will begin budgeting at around 10% loss of compression.

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I appreciate everyone's feedback........glad the piston and rings and compression held up well. The engine was run on redline, golden spectro and elf synthetic blend with a well oiled air filter. The original owner bought the bike in July of 2000 and broke his back after putting a few hours on the bike. It sat in his garage until 2007 when I purchased the bike.

That should explain it's longevity. This images shows the build up of carbon on the crown through the spark plug hole. I poured a little marval mystery oil inside and let sit for a hour and wiped the reachable area on the piston clean with a Q-Tip. The mess cleaned up well. The Synthetic oil did it's job. I am going to run the bike another season!

DSC04490.jpg

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..... wow:bonk:

so everyone be one the look out for a thread on " my bike wont turn over " soon

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A compression test tells you nothing except for compression ring sealing. Inspect if you don't know the history and condition. If it is good inside, reuse everything but the gaskets. Cost would be little that way. If it really needs more, it will still be cheaper than a scattered piston in the long run.

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i would, at the very least pull the reed block to get a look at the intake skirt. the crack will be evident if its starting. i have had numerous hondas from 96 up to a couple of 01's in varying degrees of tune, and one thing i can say is, all of them that had the stock cast piston in them developed the crack eventually. and i would consider myself way above anal when it comes to maintaining my bikes. its just the nature of the beast. when the stock rings get worn, it allows the piston to rock a little in the bore, thats where the crack comes from. if you think you are ok with it, rock on, but if it were me, i would at least take a peak to see what im working with.

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