Top end cleaning question

[chris kuba]

I took the top end apart on my '99 KDX 200 for the first time yesterday (bought it used) and found some terrible things. First, the piston is stock and unbelieveably carbon covered. I don't know how it ran. Second, the entire inside of the cylinder wall was covered in brown burned looking carbon with some spots of rust. The KIPS and everything else were in terrible shape. I want to know if the cylinder is still OK in anyones opinion without seeing it. And if it is OK to put the whole head in a parts cleaner. Can I get the cleaner in the coolant areas? I never did a top end before but it seems pretty easy. I don't get to ride too much either and the bike ran strong before I decided to change it. Glad I did! Thanks for the help.

 

[nectar]

Not sure if everything is ok, but I've used oven cleaner on the head to clean the kips, and also on the cylinder...if you try this method..do not leave it on for more than 20min., as it will eat the metal. wash off in warm soapy water. try deglazing the cylinder with a 'green'? pad...I forget the name of the things...good luck with it.

 

[Tom Cox]

The green thingy.

nectar, got you started right. Use oven cleaner to get the carbon off. The green thingy is normally called a Scotch Bright pad. They come in different coarseness and there are different brands other than Scotch Bright. From your description it sounds like the rings were worn out and allowing a lot of blow-by down the cylinder wall. You might want to have your local dealer check the cylinder to see if its worn out and needs replaced or redone. But, what you can do is get a new stock piston ring and find out what the limits are for ring end gap. Clean the brown off the cylinder wall and put some light oil on it. Push the single ring in with the piston (note clean piston first). Start at the top of the cylinder and then push the ring down the cylinder at 3/4 inch intervals the full length of it and measure the ring end gap each time. If the end gap is beyond spec, the cylinder needs to be redone. When done, wash everything with warm soapy water and rinse well with fresh water.

 

[chris kuba]

Thanks for the advise. Sounds like blow-by is a reasonable cause. I will try the scotch brite pad and check the end gap as well. Thanks again from the amature.

 

[strider80]

Thanks for the advise. Sounds like blow-by is a reasonable cause. I will try the scotch brite pad and check the end gap as well. Thanks again from the amature.

I bought a gallon of parts solvent and a stiff brush for the bulk cleaning, then a can a brake cleaner on all the parts to get off all the solvent. For the final cleaning I put everything in the dish washer(KIPS parts in a spaghetti strainer), use your own discretion when it comes to roommates or wife and how they might react to engine parts in the kitchen. But all the parts were clean enough to eat with! I heard from an engine builder that you "should be able to eat cheeiros out of the oil pan before you put an engine back together," again use your own judgment, it worked for me!