engine mounts for road bike?

for the engine mounts you might be able to make them or look at the vendors here and see if they make them. Your chain to me looks pretty good etc. I wonder if your chain is maybe twisted some where in the links. if you take the chain off the bike and find that it will not lay straight its whole length that might be the cause of the chain jumping off. you can find replacement chain at some farm tractor supply shops #41 chain is supposed to be a good one for replacing the chain and some bmx bike chains will also work. Do a little looking as some lowes and home depot stores will also carry the #41
chain. See what you can find for the best price.
Looks like your pedal cranks are aluminum so I don't think you can safely bend them but then you might be able to if you want to take the chance on them maybe breaking while tweaking them to clear the engine. How much do they need to move to clear the engine? Some bike shops sell extended cranks as well as some of the engine vendors. I'm surprised that the pedals hit the engine.

If you have long enough studs put some spacers between the rear mount and the motor (a couple of 5/16" nuts or stacked washers will work) then simply slide the motor higher up on the down tube. If you play around with the spacing you may find you don't even need the tensioner any more.

This should work out well for you:
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