Coolant in crankcase = no fun

[GMP]

If it got hot enough to change color I would check the cyl as well.

lankydoug,

Your example is exactly what happened to our GG XC125, except the pressure would blow the cap even before the bike got hot, and there were traces of oil in the coolant. Compression/combustion pressure is a lot higher than cooling system pressure especially when the bike is cold, thats why its likely in this case the oring is an effect not a cause.

[stainlesscycle]

yeah, i had assumed the nikasil was blown - i didn't even look at it - just set it aside for cleaning/inspection later.

[gasser]

Originally Posted by stainlesscycle

yeah, i had assumed the nikasil was blown - i didn't even look at it - just set it aside for cleaning/inspection later.

Call me if you need a 300 cylinder and head. The cylinder has less than 30 minutes run time since it was replated. I'm in East Tennessee.
Ken 931-498-5113

[stainlesscycle]

don't need a top end - have one with just a few hours on it.

crank builder said crank lobes were out by .008" and spacers showed wear (which i know is not common on other cranks - not sure if it's a common gg trait....) . pin was good, but bearing had some wear. i noticed a bit of a groove on ignition side where seal rides. hopefully i can position new seal in better location. i wonder if the play in the 2 piece bearing had anything to do with the groove, or if the lobes being out was my vibration i was chasing. builder also said crank DEFINITELY had some hours on it. although the rod felt fine, i'm glad i rebuilt it - at least i know what's in there now. with a regular bearing in there and newly built crank, hopefully the vibes will go down.

[gasgasman]

How much more would it be to have the crank balanced, if your builder can do it?

[Neil E.]

The .008" runout is the source of your vibration. The crank has to run true before you look at balance problems. A properly assembled crank will have less than .001" runout. The crank seal will groove the shaft if it has high hours.