250 Rebuilding KX250

AdamRides87

AdamRides87

ossagp:
I am on my phone, and I can't see any preignition. The piston looks "washed". Rich in at least one range in other words. The piston has lots of time on it and I might feel different when I look at it on my PC.
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It's been at least 3 years since the top end has been changed. For two and a half years it was very rich on the pilot circuit. You have a very good eye :thumb: There is scarring on the skirt. 2 relatively deep ones. I'll take another pic tomorrow of the piston as it has been removed
 
Mihylo33

Mihylo33

Yeah you got some detonation going on there. How does the head look? Cylinder?
A good motor guy can cut the head and change the squish band for you to help with the detonation. Race gas will also work but you can probably run 1 gal race to 2 gals of pump if you have zero motor work done
 
AdamRides87

AdamRides87

Mihylo33:
Yeah you got some detonation going on there. How does the head look? Cylinder?
A good motor guy can cut the head and change the squish band for you to help with the detonation. Race gas will also work but you can probably run 1 gal race to 2 gals of pump if you have zero motor work done
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The piston is rather scarred up and the cylinder wall doesn't look much better. I order a manual from RM and am currently waiting on shipping. Does anyone know off the top of their heads if that is a nickel plated cylinder? I'll get some more up close pics of the piston. Took the KIPS system out and it was horribly caked in carbon. So bad so that the exhaust valves were stuck in the head. While trying to pull the left one out it broke in half.
 
Mihylo33

Mihylo33

I would send that cylinder out to be replated. Millennium cylinder replaying is in your neck of the woods. Have it set to original oem specs then just gap the rings properly.
 
O

ossagp

Still on the side of "light". I have nothing against Lucas, but I have seen some engines that ran a long time on virtually everything. The trick to a clean one with valves that move easily is 16-24:1 mixes. You got lots of time out of that one so it may not be what you want to do.
 
snowflake

snowflake

To clarify, a lot of the reason I don't like them is all the miracles in a bottle they sell coupled with some outlandish advertising, I'm sure the 2 stroke oil works just like the rest of the api certified ones.
 
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