??Carbon buildup??

[440racer]

I pulled the valve covers off my CR 125 that wouldn't start and they were stuck open with carbon deposits (that's what the Clymer manual I'm using calls them). The manual said to soak them with industrial oven cleaner to remove the deposits on the valves once they're removed.

The manual also said the head should be decarbonized every 3 races or so many hours.

I have no idea how to decarbonize they cylinder, head & valves unless they mean to remove everything and soak it with cleaner.

Any help on how to decarbonize would be appreciated or am I headed in the wrong direction?

 

[muddy226]

I'd go steady with the oven cleaner, or not use it at all, it can be quite harsh on ally and particularly on any anodised parts. The only way I've found with power valves is patient work with small brushes and solvent. As for carbon in other parts of the engine this shouldn't be as much of a problem as there won't be as much and it is easier to scrape off.

 

[440racer]

muddy226, thanks for the advice. I was a little concerned about soaking in oven cleaner. I keep reading use "solvent" hear & there. What kind of solvent is best to use for this type of thing? Also, one of the valves is stuck in the guide (the guide is removable from the cylinder and both are out) The only two ways I can think of to get the valve out of the guide is to soak it in something or heat both up in an oven. Any ideas on that?

 

[muddy226]

Solvent would be something like engine de-greaser, although I usually start off with petrol and go from there. I am not familiar with your particular bike but you could try soaking the parts in degreaser, diesel fuel or the like, and if this doesn't work maybe apply heat to the guide in the hope of breaking the bond.

 

[440racer]

Thanks Muddy 226. I've left them soaking in degreaser overnight and will heat them tonight if I still can't get them apart. I would just go buy new ones but ther $136 each so I think I'll try to clean them. Thanks again.