Stihl ms 460/660 Hybrid. 469e

[ManiacalMark]

I've had great results with just boring the choke area and not touching the throttle or venturi areas. It's all about high/low pressures and how they help to draw fuel.

Agreed, I bored the Venturi on a wj years ago, ran like shiitake, pretty sure it increased spit back too.

Also pretty sure the one Rick Hennessee 440 had a HD8 on it.

 

[NateSaw]

Working around current fueling is a poor train of thought, I’d chase air first, then mod a carb to fuel what I desire…

Modding or large carbs isn’t that a small carb can’t keep up, it’s that a larger or modded carb may allow you to either make more peak power, or move your peak power up and cut faster. Keeping a stock HD on the saw it will be constrained to warm 046 levels imo. Just a hack, take it for what it’s worth

This. I'm chasing more air. Fuel is satisfied and then some.

 

[huskihl]

This. I'm chasing more air. Fuel is satisfied and then some.

Could be in the pump itself, not necessarily on the fuel side. Seen a 79 cc echo hybrid smoke my 7900 and 500 with an HDA carburetor a little bit bigger than what’s on a 357.

 

[NateSaw]

Could be in the pump itself, not necessarily on the fuel side. Seen a 79 cc echo hybrid smoke my 7900 and 500 with an HDA carburetor a little bit bigger than what’s on a 357.

You've found my stupid. I'm afraid I don't understand... The pump? Impulse?

 

[bogieboy]

Yes, I bought one from HL. Couldn’t pass it up - it was $15… We’ll see how it times out if I find a saw to put it on.

I didnt crunch any numbers other than squish.... which came out to .0205 without a base gasket on my particular saw...which is running pretty darn good i would say...LOL

 

[NateSaw]

Likely too long for most of you. This was more of a case study I guess. I worked my way down a mulberry I dropped to put it to functional use. I wanted to work the full range of throttle. I think it's safe to say the carb is fine. It's peaky. Could use a bit more torque... I'd like to spread the power band a little. I think gentle work on the lowers and uppers may be all that's needed...

 

[Powerstroke Cowboy]

It sounds good. Was that the low speed srew you kept adjusting or the high speed?

My opinion might not be right, but, it looks like you need more fuel from the high side. I might not be reading the signs right. But the way it seems to stall out quick and jump in the cut makes me think it's running lean on the high side.

Or your chain was just grabby?

Take it for what it worth.

 

[huskihl]

You've found my stupid. I'm afraid I don't understand... The pump? Impulse?

The cylinder is an air pump. Keep trying to make a better pump

 

[NateSaw]

The cylinder is an air pump. Keep trying to make a better pump

Gotcha! Yeah man I'm goin back in. Little at a time!

 

[NateSaw]

I didnt crunch any numbers other than squish.... which came out to .0205 without a base gasket on my particular saw...which is running pretty darn good i would say...LOL

So that's with the cross cylinder, as is out of the box?

 

[NateSaw]

It sounds good. Was that the low speed srew you kept adjusting or the high speed?

My opinion might not be right, but, it looks like you need more fuel from the high side. I might not be reading the signs right. But the way it seems to stall out quick and jump in the cut makes me think it's running lean on the high side.

Or your chain was just grabby?

Take it for what it worth.

I was adjusting both. In the beginning, just getting the idle to calm a bit. Then, I was playing with high. I had it leanish deliberately, was trying to work towards a sweet spot. I think @huskihl is right, it's the pump. Being fixated on the carb, without running it more has been a distraction. However, it's been a wonderful discussion about some carb theory. And proper approaches. But yes, it was too lean. I can't blame the chain. 33rs hand filed with a 7/32 file, rakers @ 35thou. This is exactly what I run on the 446 hybrid. It's my favorite profile for ease of filing, and longevity of the cutters. It is pulling some chips, but it's not stupid aggressive. Cutting up this tree gave me a chance to work at different throttle positions. I have to say I'm pleased. All the small wood was cut at 1/4-1/2 throttle. Good response. Good gontrol. It's in the heavier wood I can see it needs more torque. It needs to be tamed a bit. I'd like to take some power from 11k rpms, and sprinkle it a little lower. While I'm waiting for the cabers, I'll do like @Ketchup suggested, and just run it. I'll try a 28" on it too. When I do get the rings, I'm going to even the uppers and open the lowers. I appreciate your input David. You aren't wrong!

 

[drf256]

Then I vote to go to a one size smaller jet and let it rip.

It’s actually the opposite. A larger carb on less displacement needs more jet, not less. Moves less air so pulls less fuel. Happened to me with 026/044 carb swaps.

BTW, there ain’t much Venturi in the WJ.

 

[Rich Fife]

It’s actually the opposite. A larger carb on less displacement needs more jet, not less. Moves less air so pulls less fuel. Happened to me with 026/044 carb swaps.

BTW, there ain’t much Venturi in the WJ.

I kinda learned this on a dirtbike... with a big bore it needs a smaller jet because itll pull more vacuum/fuel. Whereas the smaller bore requires more fuel/bigger jet.

 

[Powerstroke Cowboy]

I was adjusting both. In the beginning, just getting the idle to calm a bit. Then, I was playing with high. I had it leanish deliberately, was trying to work towards a sweet spot. I think @huskihl is right, it's the pump. Being fixated on the carb, without running it more has been a distraction. However, it's been a wonderful discussion about some carb theory. And proper approaches. But yes, it was too lean. I can't blame the chain. 33rs hand filed with a 7/32 file, rakers @ 35thou. This is exactly what I run on the 446 hybrid. It's my favorite profile for ease of filing, and longevity of the cutters. It is pulling some chips, but it's not stupid aggressive. Cutting up this tree gave me a chance to work at different throttle positions. I have to say I'm pleased. All the small wood was cut at 1/4-1/2 throttle. Good response. Good gontrol. It's in the heavier wood I can see it needs more torque. It needs to be tamed a bit. I'd like to take some power from 11k rpms, and sprinkle it a little lower. While I'm waiting for the cabers, I'll do like @Ketchup suggested, and just run it. I'll try a 28" on it too. When I do get the rings, I'm going to even the uppers and open the lowers. I appreciate your input David. You aren't wrong!

Okay, sounds like there's more torque to be had just by fattening the mixture up. Lean makes peaky hp with less working grunt.

 

[Rich Fife]

Lean makes peaky hp with less working grunt.

All modern saws need more grunt... for my liking. Lol

 

[ManiacalMark]

Here’s mine just got it running, I’ll play with it more later have other stuff to do.

 

[NateSaw]

Here’s mine just got it running, I’ll play with it more later have other stuff to do.

Bada$$!

 

[ManiacalMark]

Doesn’t seem to run too bad so far, compression feels good for running too ring only.

 

[NateSaw]

Doesn’t seem to run too bad so far, compression feels good for running too ring only.

Top ring only you mean? That hasn't caused me any notable performance losses. Yet.

 

[ManiacalMark]

I think for only making 4 or 5 cookie cuts it’s hard for me to judge. It cut nice in the clean log but I hit a piece of metal in it so I have to trim it and prop it off the ground.