661 Oil Test 32:1 vs 40:1 vs 50:1 ?

[bwalker]

The 576 AT I ported was pig rich with short bars. Anything under a 28" I had to run an 8 pin or really push on it to get it to quit 4 stroking in the wood.

Not sure about the 576, but my 562 runs spot on all the time. And that's using from 16" to 24" bars which is on the extreme side of what a 60cc saw can do in our wood.
Only thing I know about the 576 is that it never gained ecceptance by loggers around here.

 

[Ron660]

The 576 AT I ported was pig rich with short bars. Anything under a 28" I had to run an 8 pin or really push on it to get it to quit 4 stroking in the wood.

Mike, think I should run an 8-pin or 7-pin on a ported 372? I'll be using a 20-24" bar on hardwoods mostly.

 

[Ron660]

Depends on chain. I usually stick with a 7 for a 372.

For now all I have is Oregon LGX chain. Thanks

 

[Ron660]

I meant how aggressive and low of rakers. I like Oregon better than stihl now. The stihl QC IS hit and miss it seems. Going to be using a lot of stihl 404 since I got a bunch from redbull.

Nothing aggressive for now. Not really sure of the best angles for round filing. I've been practicing square filing on the 660 chains.

 

[Trx250r180]

figured out the screenshots on the camera scope thing

ms461

 

[Trx250r180]

440 hybrid ,can see the oil droplets on the cylinder

 

[bwalker]

440 hybrid ,can see the oil droplets on the cylinder
View attachment 466148 View attachment 466149 View attachment 466150 View attachment 466151 View attachment 466152 View attachment 466153 View attachment 466154

Better pics. Your trapping alot of mixture in the squish area it would appear. A properly machined head seeks to eliminate this, but with a saw your options are limited.

 

[KG441c]

I meant how aggressive and low of rakers. I like Oregon better than stihl now. The stihl QC IS hit and miss it seems. Going to be using a lot of stihl 404 since I got a bunch from redbull.

Bought me several more loops 404 from him also

 

[Trx250r180]

Better pics. Your trapping alot of mixture in the squish area it would appear. A properly machined head seeks to eliminate this, but with a saw your options are limited.

The 461 in first set of images with the quad ports seems more carboned over in the squish area ,it has a machined head as well ,wonder if the extra finger transfers have anything to do with the wash on the squish band of the hybrid ?This saw revs higher than my others do .My other hybrid looks closer to what your 260 piston looks like .but a little less wash by the transfers

 

[bwalker]

The 461 in first set of images with the quad ports seems more carboned over in the squish area ,it has a machined head as well ,wonder if the extra finger transfers have anything to do with the wash on the squish band of the hybrid ?This saw revs higher than my others do .My other hybrid looks closer to what your 260 piston looks like .but a little less wash by the transfers

Even though your head is machined the squish angle is more or less flat, correct?

 

[Trx250r180]

Even though your head is machined the squish angle is more or less flat, correct?

Yes this one is machined ,my other hybrid has an untouched head (round chamber not D shaped ) ,just some port and piston mods ,the squishband is extra wide on this jug for some reason also

 

[bwalker]

A squish band like that basicly doesn't function as a squish band. In other words there is no pinching or pushing mixture from the outside of the cylinder inwards. The result is alot of unburnt mixture at the edges.

 

[Moparmyway]

What should a properly machined squish band look like ?

Isn't it supposed to be tapered toward the center of the chamber?

 

[bwalker]

That would depend on what your goals are, but the band should actually be at an angle in relation to the piston, not parallel as in most saws. The idea being to create turbulence to aid combustion and to squeeze mixture toward the center of the combustion chamber.

 

[Trx250r180]

Here is a stock meteor jug off a ms460 ,is this closer to an ideal band ?

 

[bwalker]

Here is a stock meteor jug off a ms460 ,is this closer to an ideal band ?
View attachment 466197

No, because the angle is flat, although the combustion chamber has a better shape.

 

[Trx250r180]

Here is my other hybrid with the uncut squish ,it is a round band ,narrower than the meteor . Can see some transfer wash on this saw .

 

[Ron660]

If properly tuned, should a saw stop 4-stroking as soon as its under load or say 1/4 into the wood? I set mine to stop 4-stroking as soon as it enters the wood....under load.

 

[redbull660]

If properly tuned, should a saw stop 4-stroking as soon as its under load or say 1/4 into the wood? I set mine to stop 4-stroking as soon as it enters the wood....under load.

what about tuning for time?

I spent a lot of time messing with the MM084 and TM880. In the end I settled at 12,500 on the 36" bar. I got a lot of comments that they sounded too rich. But that is where they cut the best. I tried 12k, 12.2k, 12.5k, 12.7k, 13k. 12.5k was the best times.

Then what about the 361 oil test? For a stock saw I tuned each ratio to the called for idle (think it was like 2800) and then top end for the called for 14,000 wot. I'm sure the best ratio would be different for a different oil. Probably closer to 32 or 40:1.

But look at the times and temps. The fastest times are right around where the coolest temps are. Same with the 660 test (see attached).

Seems to me it would be a lot easier to just figure the fastest cuts for each bar and note the RPM used. Then just tune to that RPM.

Obviously double check make sure by ear your not to lean...seems very unlikely.

Thoughts on this approach?

 

[Trx250r180]

what about tuning for time?

I spent a lot of time messing with the MM084 and TM880. In the end I settled at 12,500 on the 36" bar. I got a lot of comments that they sounded too rich. But that is where they cut the best. I tried 12k, 12.2k, 12.5k, 12.7k, 13k. 12.5k was the best times.

Then what about the 361 oil test? For a stock saw I tuned each ratio to the called for idle (think it was like 2800) and then top end for the called for 14,000 wot. I'm sure the best ratio would be different for a different oil. Probably closer to 32 or 40:1.

But look at the times and temps. The fastest times are right around where the coolest temps are. Same with the 660 test (see attached).

Seems to me it would be a lot easier to just figure the fastest cuts for each bar and note the RPM used. Then just tune to that RPM.

Obviously double check make sure by ear your not to lean...seems very unlikely.

Thoughts on this approach?

My saws seem to pull better a tad rich with the 32 inch bars ,kind of helps em chug along some over some rpm loss .