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Risk of running worn cylinder


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NSAAGGHHH

 
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Risk of running worn cylinder

Sun Sep 18, 2011 2:03 am » Post: #1 » Download Post

What's the risk in running a cylinder with the cross hatching worn down to almost nothing?

I'm doing a top end rebuild ATM and after A good clean up the cylinders are looking good, but the top cylinder in the top 2cm of Nikasil only has the slightest amount of cross hatching -in some areas virtually none.

I know this isn't good, but I'm considering a 275 or 300 conversion at the next rebuild ( opinions on either are welcome too) So I assume I could /will loose some compression but is there anything more sinister likely to happen if I run this cylinder?

Also electrosil quoted $440 for re-Nikasil anyone know anywhere else in Aus that I can get a quote?
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anonymous.shyster
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Sun Sep 18, 2011 4:53 am » Post: #2 » Download Post

The only other place that I've heard of in Aus is referred to as the guy 'up north qld'. Every report I've heard is negative. So the only option is Electrosil or send it overseas. I'd be tempted to send it overseas as Electrosil have a monopoly and charge as much as they like and word on the street is they often underquote.

Langcourt in the US is good by most reports. $180US to replate ($20 extra if the have to remove the powervalve and another $20 if they have to remove the head studs). So remove them yourself if possible. Postage is about $60 - $70 each way. So potentially you're looking at $320 for a replate. Send a new piston over with it so they can match the sizes.

You're probably being pedantic about the cross hatching being almost worn through. If there is no scouring or chipping through in to the aluminium, quit your worrying!
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nxrsr20

 
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Sun Sep 18, 2011 6:50 am » Post: #3 » Download Post

Measure your cylinders and see if they are in tolerance. The risk of having a bore out of tolerance is piston slap, usually showing the symptons of cracked piston skirts if caught early, and a messy messy seizure if left to destruction.
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NSAAGGHHH

 
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Sun Sep 18, 2011 10:51 am » Post: #4 » Download Post

Very Happy cheers guys! Too much coffee an seizure research is making me paranoid Laughing

The top end kit should arrive tomorrow, I'll do a clearance check before I re-fit everything - guessing fit the piston into cylinder then check the clearance between piston and cylinder im guessing without the rings? What are the clearance tolerances?
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NSAAGGHHH

 
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Sun Sep 18, 2011 10:55 am » Post: #5 » Download Post

http://www.nsr250.net/forums/viewtopic.php?t=10461&highlight=measure+cylinder

Found this Smile
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