460 bogging in willow.

[THALL10326]

Sounds like saw running with a chain too tight to me, wet wood wood cooling it and contracting it even tighter.

 

[1953greg]

wdchuck

if the rings are ok, their "looseness" can be seen by rotating the crank back n forth very very slightly, via the flywheel, while watching the rings through the exhaust port.

maybe some carbon under the decomp valve???

 

[wdchuck]

Good Morning...

Windthrown, your explanation helped me understand this more, thanks.

Pest, the taper on the exhaust port is evident on the top, but the sides and bottom are slight to negligable, the 'crown', as you describe is more than 1/16" above the bottom exhaust port lip/edge, at Bottom Dead Center.

Thall, chains are tensioned so when I pull on it at mid bar three-five teeth partially show, but no sag. But I can certainly try it a little looser to see if there's a difference, but it may allow more crud to get in the bar groove.

The ring check I did was under the thought that they would float up/down, didn't see any movement that way.
....After stopping at the Stihl dealer to get Seafoam(didn't buy it), their tech was at the counter, he said the rings float in/out of the groove, so when we were back home I checked for in/out movement and it is plainly visible that they move freely. When I described the light brown color inside the stock muffler to him, that apparently is a sign of proper running, whereas the black in the DP muffler is a sign of too rich running. Did get a new sparkplug though.

At the local autoparts store, they had a nice compression tester, thread in type, $35, they helped me check the saw comp in the store, 175psi.

Learning new stuff from everybody.

 

[Cut4fun]

Well I give up. Just set the 460 down and get you a good poulan 3750 60cc with 22" buried. :biggrinbounce2: mine cut through weeping willow without problems, stump, trunk, limbs and all to 4 inches off the ground.
Really i hope you figure it out though, good luck.

 

[ericjeeper]

Put the stock muffler back on it.

sounds to me like she needs some backpressure.

 

[TimberPig]

Windthrown, your explanation helped me understand this more, thanks.

Pest, the taper on the exhaust port is evident on the top, but the sides and bottom are slight to negligable, the 'crown', as you describe is more than 1/16" above the bottom exhaust port lip/edge, at Bottom Dead Center.

Thall, chains are tensioned so when I pull on it at mid bar three-five teeth partially show, but no sag. But I can certainly try it a little looser to see if there's a difference, but it may allow more crud to get in the bar groove.

The ring check I did was under the thought that they would float up/down, didn't see any movement that way.
....After stopping at the Stihl dealer to get Seafoam(didn't buy it), their tech was at the counter, he said the rings float in/out of the groove, so when we were back home I checked for in/out movement and it is plainly visible that they move freely. When I described the light brown color inside the stock muffler to him, that apparently is a sign of proper running, whereas the black in the DP muffler is a sign of too rich running. Did get a new sparkplug though.

At the local autoparts store, they had a nice compression tester, thread in type, $35, they helped me check the saw comp in the store, 175psi.

Learning new stuff from everybody.

Was that checked cold or hot? Try both to eliminate the cracked piston causing a compression loss theory.

 

[1953greg]

wdchuck

175psi!! well wdchuck u just confused everyone now.

does the chain rotate freely by hand after engine bogs?

does flywheel rotate freely?

maybe try another bar n chain if available.

maybe try a different wood.

try to isolate the problem between internal and external.

although i cant imagine enough external friction to bog a 460 down. heat/smoke would b apparent somewhere very quickly

when you say bog, do u mean chain completely stops or engine rpm's drop?

 

[wdchuck]

Compression check was done cold, will try another test after it's warmed up. No saw running till the kids go down, then I get garage time. 2pm.

 

[wdchuck]

175psi!! well wdchuck u just confused everyone now.

does the chain rotate freely by hand after engine bogs?

does flywheel rotate freely?

maybe try another bar n chain if available.

maybe try a different wood.

try to isolate the problem between internal and external.

although i cant imagine enough external friction to bog a 460 down. heat/smoke would b apparent somewhere very quickly

when you say bog, do u mean chain completely stops or engine rpm's drop?

Certainly wasn't my intention, just couldn't supply the information untill I acquired a tester.

When I study the vids from yesterday, it bogs pretty quick into the cut, and my pressure is only enough to keep it in the wood, then if I just let gravity take care of the rest it cuts fine, holds rpms, but takes forever to get through the round. The chips are nice sized, so no dull cutters.

 

[wdchuck]

Only did one check on the compression in the parts store.

My plan when I can get back out:
put the saw back to stock
original muffler cover
set screws according to the manual
put new plug in
make sure oil channel is clear of debris
warm the saw up
check the rpms with the tach, for a start point, and tabulate what I read and do
cut a willow cookie, then find something else to cut on that's similar in size.

back to bench and check the rpms, and compression.
post my findings here.

Is this a good starting point to work with?, any suggestions.

 

[Cut4fun]

Just a thought. What about timing. Flywheel loose and moved off keyway maybe and changed timing. Just tossing bones now.
Cause i am lost on this one without it being in my hands.

 

[lesorubcheek]

I don't think its been asked yet, but have you tried cutting something other than the willow since you've had this problem? If you have something available, I'd try some test cuts maybe starting with some soft wood and then try some hard wood and see how the saw behaves. If the saw's bogging in cases other than just the willow, and since it appears you have fine compression, I'd look into a possible fuel delivery problem. Maybe some small particles in the carb, or a slight tank venting problem or some other slight blockage.

Good luck,
Dan

 

[RiverRat2]

On my 346, there was a tab in the ring groove to stop it from spinning in order to prevent the ring ends from ending up in either the intake or exhaust ports. This is how it was explained to me at least.

Ian

Correct that Tab is called a ring post,,,, and its job is to do just that, Keep the rings where they are Post to stay,,,, OK,,,,,,,,,, just Glad the rings were not stuck, I would reset WOT R's @ spec I think is 13.5K and see what it does, try it in different wood,,,get a new chain,,,, Drink a few beers and Scratch my watch, & wind my A$$,,,,,,,,,,,,,,,,,,,,,

 

[wdchuck]

Okay, went out and put it back to stock.
original muff cover
new plug in
low idle is at 2800
high turned out 1full turn= 14,120rpm after letting it warm up
....chain tension okay, could pull the chain backwards with bare fingers without much effort.
....put it into willow, bogged quick, could stop the chain fairly easily.
....next, put it into 40" silver(soft) maple that had fungi on it, kinda punky, same result.

Back to the bench, checked compression hot, 160+psi, repeatable.
....turned the H screw 1-1/4 turn out from stop = 13,200.
....same relults in both wood types, could pick up on rear handle and stop the chain no problem. Then it would sound the same as if the brake were on and you snapped the throttle.

 

[Woodie]

it bogs pretty quick into the cut, and my pressure is only enough to keep it in the wood, then if I just let gravity take care of the rest it cuts fine, holds rpms, but takes forever to get through the round. The chips are nice sized, so no dull cutters.

Maybe it's just me, but I'm rarely using much more THAN gravity to cut with...I don't mean to be insulting here, but is it possible that you're dogging it too much? Seems to me if you're pulling nice chips and keeping the spins up, the saw may be cutting optimally.

Climing back into asbestos boxer shorts...awaiting the flames:angry2:

 

[Woodie]

Maybe it's just me, but I'm rarely using much more THAN gravity to cut with...I don't mean to be insulting here, but is it possible that you're dogging it too much? Seems to me if you're pulling nice chips and keeping the spins up, the saw may be cutting optimally.

Climing back into asbestos boxer shorts...awaiting the flames:angry2:

Wdchuck, we posted at the exact same time, and based on reading your last post, I would say you could probably disregard what I just said...

 

[wdchuck]

The tach readings are with the clip on the plug boot, thought it might provide more accuracy/reliability.

 

[Cut4fun]

Wdchuck, sounds like you better break out the Wildthing to cut up the willow tree, without any problems I bet too.
You know the 460 needs a breather, because it sounds tired or lazy.

 

[sugarbush]

The tach readings are with the clip on the plug boot, thought it might provide more accuracy/reliability.

have you checked your drum bearing and the end of the bar, chain may be pinching in the tip under pressure.

 

[wdchuck]

What's the white nipple for, location- looking at the H/L screw holes, up about an inch or so, under the intake shroud. visible through the gap in the body.

I'll go out and put the 20"er on and try the same cuts.