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Old 05-26-2014, 03:31 AM
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Lightning Boy Lightning Boy is offline
Motorized Bicycle Elite Member
Join Date: Apr 2014
Location: Michigan
Posts: 188
Default Re: New here, with a DIY Chainsaw Bike

The new exhaust system was slowly working itself loose from the head, so I went back to the drawing board for some improvements.

First, I made a spark arrestor from an old drag racing 327 gasket. (The stock screen didn't fit anymore and was decreasing performance slightly without one.) After peeling away the fiber of the gasket, I was left with a very strong screen, albeit with larger holes than the stock saw example. Clearing the holes fully with a nail and air compression finished the preparation. Then, it was easy to cut for size and drill the mounting holes. It slid right into the header easily, and bolted up in a flash.

I realize that I don't technically need the spark arrestor now, but the behavior of the bike says otherwise. The extra baffle really helps the sound level, and stopped the fluctuations in speed on the extreme top end. It's completely different riding without it.

Also, I decided it would be a good idea to make a matching gasket for the new port box. A few broken aluminum 350 gaskets worked perfectly. All I had to do was score the port and holes into the gasket to trim and drill them out.

These two things and a shot of loctite on each of the head bolts made for a much improved exhaust. There is no wiggle between them now. Volume has decreased, and performance is very close to its former self. If it stays attached, we may have a winner here.

Last edited by Lightning Boy; 05-26-2014 at 10:32 PM.
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