Originally Posted by Mr.B.
Yep, I can think of lots of cosmetic stuff, but with the cylinder sticking out the back at a shallow angle, that may be a deal breaker...?
These Honda clone engines you are speaking of will NOT last around a city block if you tilt them in the angle your asking about here, all of these type engines have what is called a "dipper oiling system" this means they have a slim finger like probe that extends down from the rod cap on the con. rod, which when the piston in the engine is at BDC will be down in the engine oil, as the engine is running this dipper actually slings oil all over the inside of the enine and there is also a hole in the Con rod cap which will allow oil to be pushed between the crank journal and the Rod while the engine is running.
If you tilt one of these engine at that angle you will prevent the dipper from reaching the oil which will cause the engine to lock up and be wrecked in a matter of a minute or two at the most, I have built High performance Kart engines using these Honda Clones and so I know these engines very well, I have not built the little 2.5's but they are just smaller versions of the 6.5HP Honda GX200 clones.
And if the oiling wasnt an issue you would have a carb issue as well, because at that angle it would either flood with fuel or starv for fue also.
If you want that vintage look, get a briggs Flat Head and build it up, you can still buy the 3.5hp engines which would be plenty for a bike if set up correctly, mill the head down .010-.012 put an offset flywheel key in it to advance the ignition timing about 6 degrees, build you a cool straight pipe exhaust and you'll have a cool running and cool sounding engine with that old time flat head look.
Good luck on what ever you do, but dont tilt the overhead valve engines back very much or you will lock it down real quick...... guarranteed