Read many posts about de coking the exhaust and I may try a few of those. I am hesitant to do anything with the muffler as it is a sealed unit and it just makes me nervous. Going to just ride it this summer and replace next. In the mean time I took off the head pipe and it is pretty gunked up. I know with oil in the gas that the exhaust will have stuff in it but how much is normal? I could peel off thick black gunk with a screw driver pretty easily and it was somewhere between 1 and 2 milimeters thick at the muffler end. I am soaking the whole thing in degreaser and plan on buying some kind of pipe cleaner today to clean it out with. Previous owner said he mixed at 80 to 1 (2004 Sherco 290). As long as it is not too loud I don't plan on messing with the muffler at all. But if I do... it sounds like filling it with diesel and shacking the poo out of it and letting it sit for a couple days is the way to go.

So the question is... Is that amount normal and any other thoughts are welcome as well.

Thanks.

Id probably go for using Wonder wheels alloy wheel cleaner, it should break the carbon/oil deposits down pretty quickly, some industrial grade pipe cleaners would be handy too

Sounds like it is pretty thick with crud if it is that much up the headpipe. Can you still make out the little holes in the muff inlet tube?

Carbon and residue buildup basically falls into one of two classes, soft or hard. The soft will normallk break down easily using Gas or Kero as a solvent, or other solvents such as laquer thinner. Hard deposits can be difficult. Careful if you are soaking in an enclosed area as the fumes can be volitile, best put it outside.

This is where the pure synthetic oils tend to develop less crud. As an example, inspection of my '07 bike reveals little to no buildup on top of piston, slight bit at first bit of header pipe of hard carbon and little but soft residue down and throughout the rest. What is there is soft and does not seem to accumulate. This is after a full years running probably near 20 trials plus what little practice I do. You do need to ride the **** out of it on occasion if for nothing else but to blow things out! Which seems to help keep things clean by getting the temps up! They will smoke like hell when you do this. A half dozen drag races down a dirt road will usually do it, and get your blood pumping doing 5th gear wheelies at the same time!

Thanks. While I have the head pipe off I am going to try and fish around with the piston and see how it looks. Maybe try and scrape out some of the gunk (toothbrush or something would probably work well.) if there is any then when I get everything reassembled ride the poo out of it a few times. The build up is very soft at the muffler and of the pipe. Maybe next year I will rebuild the motor and clean everything out good.