Rupurt

Can anyone tell me what the taper on the shaft is in (degrees). I want to make a plate to put the magnet for the ignition in without using the magneto.

Thanks, Kevin

w8ye

My Feedback: (16)

People have been turning the flywheel itself down to make a magnet holder.

You could probably match it up with a standard taper from Machinery's Handbook like a Morse taper?

Enjoy,

Jim

Rupurt

I was just wondering if anyone knew off hand. i will probably turn down the flywheel.

BTW i have the zip start model with that compression release thing and no web on the exhuast port,
when i checked piston diameter and stroke it turn out it is a 25cc.
I have read here that if it dosen't have the web it's a 30cc but thats not always the case.

w8ye

My Feedback: (16)

The ones with the compression release right above the intake can be unthreaded and a pipe plug installed in it's place.

The little hole above the exhaust on almost all 25's & 30's has to be tapped and threaded and a set screw installed.

Enjoy,

Jim

4 stroken ron

My Feedback: (29)

I tried to measure it one time and came up with 11.5 degrees. I don't know how accurate that is, but I made an arbor with 11.5 degrees of taper to hold the flywheel, to turn them, and it holds the flywheel nice and straight.
Ron

Rupurt

Thanks i'll try that. I got my ch-ignition yesterday and cant wait to try it.

Kevin

w8ye

My Feedback: (16)

Whatever angle you make your arbor/hub taper joint, check your accuracy by printing the fit of the arbor back to the flywheel with some Prussian Blue or just by using pencil marking or chalk. That way you will know how accurate you are? But remember that your arbor is harder than the flywheel so be easy with trying your fits so you don't mark the original flywheel to the point to where it is inaccurate.

When you get your new hub turned, you can check it against the taper on the crankshaft this way.

Also, if you make a aluminum hub, and after checking, you find a high spot or slighlty off angle condition, you can lap the hub to the crankshaft with some fine valve grinding compound. Also some Locktites will fill voids that are several thousanths.

From my experience, on Homelights, The long shaft engines have a 3/8" shaft and the short shaft ones have a 5/16" shaft. The taper appears to be the same angle on both sizes but, of course, the long shaft version has a larger diameter taper. I found out the hard way that a long shaft flywheel will fit a short shaft taper but it goes too far up on the taper for the mag to work it's best.

I've seen different angles mentioned for flywheel tapers that are anywhere between 4 degrees and 5 degrees and 43 minutes. Notice that this is half the angle mentioned by Ron but this is only a matter of terminology of thinking about both sides I believe?

Good luck and enjoy,

Jim

Rupurt

Thanks for all the advise. i'll have a crack at it this weekend and tell you how it goes.

This engine was turning an 18/6 menz at 6000 (with magneto) is that the max or should i be able to get more.

SNIGGEMANN

My Feedback: (10)

Rupert,


I'm no expert at these conversions but I have recently converted a 25cc Homie. I did not ever run it with the magneto as I converted it to a CDI from the start. Using the standard carb and muffler on the motor I was able to get 6200 rpms. What you will probably need to do is get a larger bore carb and open up the muffler to lessen the restiction. I did both of these things along with using a 16X8 APC prop and achieved 8100 rpms. I am contemplating going a little further with "hopping" it up a a little more by increasing the compression and changing the intake and exhaust timing but we'll see. I may just stop where I'm at and call it good enough for what I'm gonna use it for.

Scott

Flypaper 2

Also, make the taper slightly tighter at the engine end so it wedges on when you tighten the nut. I remember one manufacturer came out with the taper tighter at the nut end. They would cut the FW key off as soon as the engine kicked. Didn't matter how tight the nut was.

Rupurt

Just got it all together and gave it a very short run. Its 10:31pm don't wanna annoy the folks. If you turn it over by hand slowish a nice blue flame comes out the exhaust port. Excellent!

Rupurt

To answer my own question 10.5 degrees seems to work best plus valve grinding paste to seat it nicely. i am getting 6700 rpm with the 18/6 now.

thanks for all the advise.