Something interesting...
 

Here is a site that has offset keys for our magnetos. I don't know if they will fit the engines we are using, but if a person is into experimenting with the ignition timing, (and using the stock magneto/ignition), they can contact them for dimensions.

The site is: http://www.tucsonscooters.com/

From there click on "Rockit Keys".

Have fun,

AV8TOR

RE: Something interesting...
 

Hello from Williams..FWIW..The function of a key on a TAPERED shaft is to locate the flywheel during assembly..The key is soft and will shear if the flywheel nut gets loose, it will not keep the flywheel from turning ...I have been converting chainsaw engines for 16 years, quit using keys about 15 years ago...Our 32 HP converted 289cc racing drone engines have no key, never had one..the hub has not shifted in 2 1/2 years of racing..You can throw away the key and just use loctite on the taper and lots of force on the nut or hub, no problem..The amount of gain by using an offset key is not worth the cost of the key, unless the engine was originally timed very retarded...Most engines run best around 28 degrees BTDC.....

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32hp? I was wondering how much power that engine had when you mentioned it to the first time. My buddy races midget sprint cars and he said that his 250cc engine running on menthanol makes about 70 hp. Could this be possible? Also could you use it? (not me, you, I know you like to go fast). Only bad thing is I think its water cooled.

RE: Something interesting...
 

If you really want to do something like that, you could always buy yourself a thicker wooddruff key (3/8" or 1/4"?) and grind it to fit. That's probably what they've done with that $10 key.

Better yet, how about enlarging the mouting holes on the pickup coil so you can shift it sideways a bit.

Kinda reminds me why I like elec. ignition so much better. ;)

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The 32 HP is an estimate from the manufacturer..His dyno shows 26 hp at 7000 on gasoline..70 hp from a 250 is entirely possible, B H Hanson has a watercooled 50 cc inline twin that makes over 12 hp..the little .40 formula one race engines make 5 or 6 hp, at 25,000+ rpm...We have a 14 lb weight limit on the race plane engines, ours weighs 13...If we could use tuned pipes the power would go way up, but we're limited to 8" pipes, same diameter all the way through...

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How come a 125cc MX bike puts out 33+ hp on gas. These are water-cooled but the basic priciple is the same. They are also very reliable. My 250cc Yamaha puts out close to 50hp with a ton of torque. Wouldn't it be cool to put one of these MX motors in a plane with a mini radiator.[X(]

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Tuned pipe, much larger transfer ports, probably a power valve,and a gigantic carb and reed valve...
a water cooled 125 would fly an ultralight...The first ultralights used a Yamaha KT 100 Go Kart engine...
3W has a water cooled prototype, check out the German 3W website...

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the kart and bike engines spin at insane rpm's in order to make all that power. some kind of reduction drive would be needed for use with our large props...too complicated and much easier to just use more displacement.

dave

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How come we do not see any KT100 Yamaha engines flying? Seemed pretty light to me when I had a few around but it's been awhile.