I welded a platform for a 3hp 4 stoke engine on an old 1960's era JC Penny Foremost steel frame. I am getting to try and finish it now with winter about to start and only outdoors to do most of the work. I'll work around the storms as best I can in California.
I think that you have as a 2 stroke as I see the intake and about half way down the cylinder so you probably have quite a bit of power and not to worry.
I can remember for a while using a street motorcycle Kawasaki 350 with 3 cylinder two stoke, was a bit worn out as it was then 3rd hand. I once reached down to grab something on the ground under the headers by the front fork and smelled plastic burning. It was the poplin shell of my down jacket. I did not get burned, but as I saw a large hole melted on the sleeve, I also saw feathers stuck to the pipe.
Covers on moving parts around chain a belt drives also I have made for the motor bike I am making.
I eventually am to make a modification to have my motor bike when it is done. It is so it can run a crawling speeds and to look like a sea creature to bring to the next Burning Man event for 2012 in Nevada.