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New piston bike hot

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Is it normal for a 450 to run hotter while breaking in new piston/rings?

It has not boiled over but feels hotter. It gets hot enough that the A frame is hot to the touch and wanted to be a stall monster. Bike was like that during intial break in but had stock exhaust and jetting. In the bikes defense it was 97 degrees outside.

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Replaced the top end gaskets with the new piston/rings. Cross hatch was redone in cylinder. Stock sized Pro-X piston was used.

I had the entire motor out of the bike. Cracked cases and replaced main bearing on left side of motor. Did piston originally to see if that was the problem. Bike fired right up and has been going through break in easy enough. Just really seems hotter, like gas boiling hot.

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IMHO, the fact that it was 97 outside (and probably some humidity too since you're in Florida) had more to do with it than anything else.

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Just had to ask...you did put the head gasket on correctly making sure none of the coolant ports were blocked right? You did refill the radiator with coolant/water right? You may have an air bubble somewhere in the coolant. If you start the bike with the cap off the radiator, do you see the coolant flowing?

Also how long are you running the bike? Are you just letting it idle or riding it?

Did you change any of the jetting to make it leaner?

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joeprunc, I did not try starting bike with cap off to see if coolant was flowing. Never even considered that. Will try tonight. Think I may take impeller cover off make sure it's spinning also. Have a spare gasket.

CB, could be right too. First weekend riding 450 after fixing it. Maybe just weirded out.

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Started with cap off coolant flowing fine. Checked old gasket impossible to put on upside down thanks to dowels being larger than bolt holes.

Might just be temp outside and me freaking out.

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I would go get a temperature strip and install it on your cylinder, then at least you know how hot it actually is. Another thought with summer here, and it being warmer you could be running lean, how does the spark plug look?

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Another thought with summer here, and it being warmer you could be running lean, how does the spark plug look?

As temps go up and the air loses density, jetting will start to run richer.

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you would be running richer in the summer because of the less concentrated air

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