Pairing up a 461 and a 661

[Boogedy_Man]

Anyone have any thoughts on how this would work as a dual-powerhead setup?

 

[BlackCoffin]

I wouldn't pair up anything but identical saws. Too many differences in max rpm, in the cut rpm, powerband, etc. they'd work against each other at any given time. Would they work yes but at a cost of degrading your saws quicker.

 

[BobL]

Max RPM is irrelevant. The RPM in the cut is determined by the combo when they are together not each saw. As long as they have their Max torque within a few hundred rpm of each other they will work just fine. It's lust like adding another extra cylinder to the same crank shaft. A large V8 and small V4 will couple nicely to make a V12.

Would I bother to do it - no.

 

[Boogedy_Man]

Bob, care to elaborate why you wouldn't bother? Gains not worthwhile?

 

[Boogedy_Man]

I wouldn't pair up anything but identical saws.

To be honest, I have quite a hard time wrapping my head around how any two saws would work together.

 

[BlackCoffin]

To be honest, I have quite a hard time wrapping my head around how any two saws would work together.

On the other end the saw would be mounted on the bar 180 degrees from the opposite saw, that way both sprockets are working in the same direction.

 

[Boogedy_Man]

I understand that part...just not how more power is made.

 

[BlackCoffin]

I think it's more about the torque when the saw starts to bog down. Instead of letting up you can keep on powering through since the saws help each other recover and stay in the powerband.

 

[BobL]

The way to think of it is like multi cylinder engine where a chain acts as the connection crank between the engines.

The concept is used in multi engined motor bikes like this one which even uses CS power heads
The powerhead are connected by chains to a centra gear box which in turn drives the rear wheel.
Starting would be a bit of a chore.

The main reason the cylinders on conventional motors are the same size is to help smooth the action of the motor out but when the crank between the power heads is a chain this is not necessary.
Of course their torque curves have to be similar but they don't need to be identical.

Why would I not do it? Well mainly because I really like milling on my own and one CS and a mill is about all I can lift.

 

[Boogedy_Man]

I see a multi-cylinder engine as different because the cylinders are properly phased for a desired outcome - which you can't do with clutches on each motor. Different phasing gets very different results, too. For example, a 360 twin vs a 270 twin. I remember synchronizing a lot of motorcycle carbs through the years, too. I don't think I ever dyno'd just for that purpose, but you could sure feel the difference in a closely matched setup. Maybe the differences peter out when you're talking chainsaw RPMs, not sure.

That's just my own random thoughts....the reality is I am asking because I have no idea and can't wrap my head around it, lol.

 

[MGoodwin]

the heart of the issue is having the power heads operating at the same optimized RPM range. The only time one saw would be driving the other, practically speaking, is when BOTH are engaged and one is running just enough to engage the clutch and the other is running at a high RPM. If one power head is off, or idling, the clutch is just free spooling. So if you were to run say an 036 and an 088, the RPM bands probably dont align very well so you would not be leveraging the potential maximum HP. Myself and PhilB (I believe its PhilB) both have similar setups where we are running identical powerheads and they are actuated together via a common cable. Granted this setup is inherently more finicky than a single powerhead, but was the cheapest means to gain more cutting capacity (I'm running twin 066's). I have used this on a 4' diameter maple and was very happy with the results.

 

[Boogedy_Man]

Great info...thank you. That's mostly what I am looking for - first hand stuff. I'm really wanting to run a bigger mill, but the idea of investing in an 880 (on top of everything else needed) is quite daunting. I've considered two Huztl 070s, but I am equally reluctant to invest in Chinese-clone technology. If I have a chance of making my current powerheads work then that's what I want to do. Again, thanks for your contribution.

 

[Boogedy_Man]

Nice Avid lever btw...My wife and I race mountain bikes on the side and once upon a time I ran a bike shop. I have a few of those laying around and was considering using one for a throttle.

 

[MGoodwin]

I to in a previous life was a biker. It functions like a brake line system where fine adjustment can be made at the screws coming in (lines are standard brake cables). One thing that annoying on the above is sometimes the cable round will jump out of the screw going through the lever. Easy enough to pop back in, have solved it with a bit of tape, just not the most elegant. Other end is a basic lever and the cable is trapped under a screw (just like like standard bike brakes). I did add a compression spring over the line and under the lever to provide some extra snap back to idle. Found just releasing the brake lever wouldn't back the throttle off quite fast enough. I prefer a bit stiffer pull on the brake lever during milling as it gives me a bit better feel (comparable to a soft car clutch?).