Hi. I just broke in a new 4Cycle Magnum .91 engine and noticed a lot of varnish on the muffler and exhaust pipe. I don't know if this is normal. I am new to 4Cycle glow engines (this is my first one). I think that I followd the manufacturers instructions to the letter. I ran the engine very rich (lots of white smoke) for 5 minute intervals and then let it rest for 10 minutes. I gradually leaned it a little (less than 1/4 turn) after each run until I accumulated 45 minutes of running time. It was still smoking a lot when I finished. I used Riche's Brew 5% nitro for fuel. Is it normal for varnish to form so quickly or did I go to lean? The engine runs great but I am just worried that I might have done something wrong. I would welcome any ideas or suggestions. Thanks

Thats normal. Just don`t let black oil come out the exhaust, thats bad. Brown is good.

Thank you for the info. I won't worry about brown varnish and try not to let black oil come out of the exhaust.

i put high temp silicone on the threads of the muffler pipe before i thred it into the head and thread the can on and whipe the excess off after i tighten the lock nuts, keeps the oil coming out the tip only and no more varnish. otherwise its gets thick enough to chip at fairly quickly

If you want to clean the baked-on varnish from the muffler, pipe or other engine part, soak it in hot automtive antifreeze for several hours. I use a "wife donated" small crock pot. Parts are like new when they soak over night. Make sure that, if you soak any thing other than aluminum, coat it with light oil after it dries as all the protective oil will be removed and it WILL rust quickly without it.