Mr. Clean magic eraser is money. I just dampen it and rub the pipes clean no problem.

 

OOOO steel wool is finer. A spritz of carb cleaner helps too.

MikeM

 

I've ued Easy Off oven cleaner and it works great, even without the steel wool. if at all possibleI would remove the pipe or guard from the bike. As already mentioned the overspray of the oven cleaner might cause problems. Good luck

 

Easy off oven cleaner , spray it on a rag as mentioned.