It's a xs650 limited by it's combustion chamber and center crank pin .
The best thing about the over bore was gaining room for quench area and even at that some careful welding to fill in some obvious voids in the chamber .
Some facts .
Alcohol has approximately half the BTU's by volume than that of good gas (not pump)
Alcohol has a greater latent heat of evaporation
Alcohol has a stoichiometric mix 6.5:1 as opposed to 14.7 for gasoline .
Most CV diaphragms and rubber parts as well as the carb bodies won't put up with straight alcohol.Even intake port erosion can be a problem .
The combustion chamber is steel on top and sides while the piston top is aluminum .
Alcohol burns much slower and it's behavior near relatively cool combustion surfaces is way different than gasoline .
So ...
toss the BS36-38's
Drop a significant sum on carbs and jets from Sudco (real good people)
Use an old Axtel mag or equivalent
Be prepared to get it wrong a bunch of times possibly torching a piston or two and get used to tearing into it on a weekly basis .
Fixed advance as much as 40 degrees
Jets you can see big screen TV through
Pistons running so close to the deck that at temperatures below 40 degrees the engine has to be heated just to provide enough deck clearance so it will turn over .
Over advancing the timing without enough fuel and "banging" the tune up and having the rod bearings "peen" the crank .
Having to carefully start the bike on gasoline then switch to alcohol .
Freezing the carbs in high humidity .
Having to nearly redesign the clutch or just spend the bucks at Heiden tuning . Might as well change the primary ratio while you're at it .
Adapt XV 700-750 valves , Buy Manley stainless valves or keep an eye out for the titanium valve guy on fleabay .
Hoos racing for the exhaust . They just get it .
Fishead brakes .
A stack of rear tires ,
And on ...
About 75 miles on a tank which drops drastically if you wrist it .
About 78 hp and nearly as much torque in one of the most sensitive to state of tune compilations I've ever owned .
I couldn't keep the thing together as a 360 degree crank . I had to twist the crank and cam . Crank is 277 degrees , You do the math for the cam I'm tired .
This was an outgrowth of the 70's Yamaha ,Shell Thuet , race program with the same caveat as then . Even with the odd crank (the object was to have one piston at or near max acceleration while the other was at minimum ) The center crank pin and it's fit to the counter weights becomes a loose pin in a hand grenade waiting for a place to happen at power levels over 80 hp . Shock load it a lower levels and see the same result .
Was it smart ? No,
Was it fun ? Not really the engine development was a drain on my time and resources .
Was it difficult ? Not really , it's just nutz and boltz .
How close was I at first get ? Left field ( more like Landsdown Street . If you savvy baseball if not nevermind )
Was it worth it ? heh heh heh . Well ok some days yes . Other days it's wtf was I thinking
.
So here we go again ....
