cooling head question

[Out Of Control]

If i get a bigger cooling head and a piston/sleeve for the trx 2.5, should i break it in with the normal head or the new big cooling head, or will it make no difference at all?

[Fluke]

i'm pretty sure it'll make no diff

[rcguy2477]

It would probably make little difference. The new head may decrease the running temperatures thus requiring you to run it at a slightly leaner setting.

[atm92484_3]

I would break it in with the stock head. Since engines require heat for break in, it will be easier to get the engine up to temp with a stock head as opposed to an aftermarket head without over leaning it.

Also keep in mind that a bigger cooling head isn't the ticket to run the engine leaner. While it can go a little leaner to get some more power, going too lean to get up to whatever temp it ran stock may starve the engine of oil and destroy the piston and sleeve. With some of these soup can heads out today, running engines at even 250 requires a dangerously lean setting.

[Duster_360]

I'm with atm92484_3, I do all my breakin with the stock head and after getting it tuned for performance, then if I need to, I put a bigger cooling head on the engine. I don't lean the the engine out further due to the temp drop from the new head either. I'd rather run slightly rich and get several gallons engine life than run it lean on oil and have to replace P/S early.