The Making of a Full Circle Crank in a Homeshop

[Mastermind]

Remember that it will also provide a lower pressure negative signal when the port is open.

There it is. Yeppers.

 

[Dieselshawn]

joining the class...

 

[jmssaws]

I'm giddy with excitement.

 

[awol]

I've been a bit curious about full circle cranks. They have been used
in the karting industry for years. I even bought a Mac 101 with a full
circle and it was made just the way your doing yours. I understand it
is filling the crank case more so when the piston is on the down stroke
there is actually more pressure to charge the combustion area. But is it
that much of a difference. Much more power? Or is it going to let the
engine spin to higher rpm's with less drag around the crank.


Lee

Hang around, I'm gonna try one in a MC101m/c someday.

 

[Deets066]

The saw this crank go's to is a 5000+ with 44mm jug. It has been a perpetual project of mine, but has taught me more about porting than most every other saw put together. Right now it has an intake block fitted, and running on a bored out WJ from an 066. It has 185 degrees of intake, 165 of exhaust, 20 blowdown.



Remember that it will also provide a lower pressure negative signal when the port is open.

Man.....185 is a lot of intake, I kinda figured they would need more but wow!

So is there truth in what I've heard that full circle cranks are not for long bar saws?

 

[angelo c]

I'm giddy with excitement.

Get yer hand outcher pants !!!!

 

[jmssaws]

Get yer hand outcher pants !!!!

It's mine and I'll play with it when I want.

 

[huskihl]

It's mine and I'll play with it when I want.

You might say you're working on a full circle crank of your own?

 

[jmssaws]

You might say you're working on a full circle crank of your own?

Well said.

Crank is leaving in the morning Alan,should be there Tuesday, your not 100 miles away

 

[spencerpaving]

I've seen a couple full circle cranks....always wondered on what it took to make them....looks great btw!

 

[Adirondackstihl]

 

[WKEND LUMBERJAK]

Subscribing.

 

[Deets066]

So.... You machine the crank to be true, then you machine two rings and epoxy them onto the crank. Then put it back on the lathe and true the rings up again?

That doesn't sound too bad

 

[drf256]

Great work AWOL.

I was wondering on this as well. I could see the heat of welding causing a lot of issues. Warpage and affects on heat treatment.

This makes sense now.

Would you mind posting how you fill with epoxy? Sounds messy.

 

[lwhaples]

Stepping in to watch,and learn.

 

[Deets066]

I would think it would be much easier if you were to tack weld the rings in place and then epoxy. At least to just hold it all together

 

[awol]

I did think about tacking the rings on first, it would make it much easier to finish up. I decided thatI will just use a thin film of epoxy, hang the crank horizontal, and get the rings fastened to the counterweights. That will make the final "stuffing" easier!

 

[plcnut]

I would think that even a tig weld would tend to warp a .025 ring...

 

[drf256]

I would think that even a tig weld would tend to warp a .025 ring...

Multiple plug welds and then you'd have to turn down the outside of the ring afterwards. I agree

 

[darkimpulse]

Subbed.