circle crank ms660

[jmssaws]

Balance was not considered for this build.

 

[Stihl working Hard]

Is it hard to build that fullcircle and keep it balanced? It thought the stuffers on my 550 was pretty neat when I ported it. 1st time Ive seen them

So are the stuffers used to slow the release of the charge into the cylinder excuse my ignorance or am i way off base here

 

[Stihl working Hard]

Balance was not considered for this build.

So you were just trying to see if it would work i can understand the RPM in the saw but how do you get the torque out of it wouldnt the saw overrun (heavy 4stroke) signed still learning

 

[Keith Gandy]

So are the stuffers used to slow the release of the charge into the cylinder excuse my ignorance or am i way off base here

Thats over my head!! Lol! Ill guess for nothing more than to take up space in the bottom compared to the topend capacity to make the saw behave differently which is for more rpm probably and what husky claims its revboost? Husky uses plastic which will make it spool up faster but full metal like Jasons would seem it would pull more heat from the bearings like a heat sink which would be a big plus

 

[jmssaws]

All I'm doing is filling dead space, same as using epoxy in the lowers. Although the crank is twice as heavy now.

 

[jmssaws]

I'm gonna put everything on a stock crank after while just to see the difference.

 

[Keith Gandy]

Id be intrested to know the difference in cut rpm?

 

[jmssaws]

I think it's going to be a runner no matter what crank is in it. It's always been a great running saw.

 

[Keith Gandy]

It already cuts good. Id like to know how much difference the fullcircle makes though. I woulda though it would add alota torque?

 

[Jughead]

one way the old two stroke race bike guys done to shave weight on stuffing cranks was to epoxy in cork.some on full circle cranks would turn down the crank diameter and "stuff" the bottom of the case to bring the primary compression back up.of course the case stuffer would have to be glued and bolted through the case.

 

[jmssaws]

The saw is running very slow and still has big rpm in the wood. Ported at 14500 will be interesting.

 

[Keith Gandy]

The saw is running very slow and still has big rpm in the wood. Ported at 14500 will be interesting.

I know u have pondered a plan!! Lol! Where r u gonna pull the rpm from?

 

[jmssaws]

I'll just lean it some,the video is the firsttime it ran so I only have it running 13200. It will go much faster now but I'm still feeling the water.

 

[GoBigBlue1984]

J,

My little brain thinks you should raise the intake to 75 and do nothing else first.

You've suddenly got less case volume, so your ratio has changed. You can't overstuff the case, it's only gonna fill so much. Too much intake will just cause loads of blowback and less case compression. You should have a smaller volume higher velocity transfer charge.

So you should need LESS intake duration. You should need less everything duration.

But your saw should rev higher than a similar 066. You created a smaller motor that should spin higher and the torque peak should be at a higher rpm. Think about the changes you like when you put a 66 jug on a 64, or a 46 jug on a 44. The changes those hybrids like should apply here. You've created a hybrid with the same parts.

That's how I see it, and I may be 100% wrong. Try it first and see what happens. You can always grind some JB weld out.

This was what I was getting at. Again, it makes sense to me but I've been wrong many many times before.

 

[GoBigBlue1984]

I still think raising the exhaust 2 or 3 degrees would be my first try.

Just trying to understand your reasoning here, what's your theory behind raising the exhaust here a couple degrees?

 

[GoBigBlue1984]

Rpm in the cut from what im seeing in the 2 044 hybrids ive built. I still like a regular 460 for the extra torque for work

I've never dyno'd any of the hybrids I've ran but they almost feel like they've got a wider power band. I suppose there are different variables at play here but essentially this what has been done in this case.

 

[jmssaws]

Just trying to understand your reasoning here, what's your theory behind raising the exhaust here a couple degrees?

To gain blow down.

 

[GoBigBlue1984]

I wouldn't, I don't think you're gonna need it. But maybe you will........lets see. What's your gut say?

 

[jmssaws]

I know it needs to come up along with the transfers.

 

[GoBigBlue1984]

I've been trying to go back and read the posts from late last night, I went to bed and missed some of this. Did you end up epoxying the lowers?