Moparmyway
Its just a saw
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Brad, would you be willing to run this with a different air filter ?
Not another HD2, but a Max Flow ?
Problematic MS661
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Not another HD2, but a Max Flow ?
I don't care to purchase a Max Flow but would willing to try one. What are you thinking?
Moparmyway
Its just a saw
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We swapped the coil and carb. There is nothing more to it.
Didn't they end up just replacing your saw, after swapping everything out made no difference?
Did anyone hear of the piston size being changed, just something I heard in my neck of the woods. Earlier ones the piston could expand and seize the saw, so they are making them a touch smaller.
Dave
Dave
I don't have a filter that I care to cut up. What is it you're thinking this might change? The saw runs perfectly at WOT, where the most air is needed. It idles perfectly as well. I'm not trying to be critical, just thinking through this logically. I'd be willing to run it no filter for a couple cuts. It's only after making a cut and idling a short time that it stumbles.
I had not heard of that. This saw has a brand new piston in it. It's actually had 4-5 pistons in it, as I experimented with different things. I've seen no indications of seizing. Of course, this is only one saw.
I think this was the reason that the odd saw just blew up. That is what the local tech told me. So they made a slightly smaller piston.
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Moparmyway
Its just a saw
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I am thinking that mine ran much better and lost the once in a while stumble when I cut my HD2 and installed the element over it.
If you want to run sans filter, thats OK with me, but I'd be willing to send you the element so you wouldnt have to run it without any filter
You could also cut an older HD filter to use for the frame and place the element over that
If you want to run sans filter, thats OK with me, but I'd be willing to send you the element so you wouldnt have to run it without any filter
You could also cut an older HD filter to use for the frame and place the element over that
@Moparmyway
Hmmm. So you've experienced this stumble as well. Interesting. I'll give most anything a try. I do have a couple screen mesh winter filters that I don't mind sacrificing.
Jog my memory on your saw. Is it ported? Is the internal baffle removed from the muffler? Is the ignition advanced? I highly doubt it's related to porting at this point. There's nothing radical in this saw at this point. That's why I replaced the trimmed piston, to remove that variable.
I appreciate the help and ideas!
You won't see any issues in this vid from last night. Like I mentioned, it has to idle a bit after coming out of the cut. It was pretty much neck and neck with my 390XP this time!
mcobb2
ArboristSite Operative
Well, nothing seemed to help this saw run right, not even another carb, including the solenoid and trigger unit. With those parts all replaced, it was clear that we weren't just dealing with a faulty part issue. So, I had the saw sent home.
The saw arrived this afternoon. I warmed the saw up so that I could experience this off idle bog for myself. I have never experienced it when I ran any 661. Sure enough, there it was.
I noticed that it only did it if left idle for a bit. I was convinced that it was fuel pooling in the intake boot. It didn't seem to be running so rich, just pooling up over time.
My first effort was to lower the needle height, thereby hoping to lean it out a bit. This didn't fix it, which is line with the idea that it's not actually running rich, but has a pooling issue.
Next, I thought I'd throw the bottom ring back in, just to eliminate the variable. This shouldn't have an affect like this, but I wanted to eliminate this variable. I was putting the cylinder back on and noticed that something didn't look right. I reached into the intake boot and noticed something that didn't feel right. What could it possible be? I grabbed a flashlight and here's what I saw.
Do you recognize what that is?!!! Remember those odd, large rubber washers that I found folded in half in the intake manifold of a 661? Well, here they are again, except I now know where they came from!
Here it is removed, a little deformed, proving that it's been out of place for some time.
So I look back in the boot and found that there was a second one in there, just like in the other 661.
So, where do these go and what are they for?
See that crack? That is the bellow. It's partially covered by a lip, coming forward like a funnel lip. The design here is to have a bellow to allow flex, but to fill it with these washer, and then cover it with this lip in order to prevent pooling. However, when you partially pull out one of those washers, you do exactly the opposite of what it's intended to do. It blocks flow and creates a pooling issue.
So, I took the bottom ring back off, put the rubber washers back in place, and put it back together. The issue appears to be gone! The real test will be to get it in some wood, but I fully believe the issue is fixed!
Brad I talked to a Stihl tech on it and he said yes that is partially the reason but the other reason is actually a little facinating to me. So the bellow is for expansion for AV reasons which makes sense but the bear of a saw draws so much air that it originally was collapsing the manifold. The ring was initially designed to hold the manifold's shape. The updated manifold is still being tested as even in some area's the ring would not hold it open, cause a saw to lean out and seize. My opinion to the whole deal... Holy cop car batman that's a lot of freakin air!
Wow. I would think it would take a LOT to collapse the intake boot. Once the throttle is opened, it's wide open all the way to the filter. Perhaps I should watch and see what it's doing when I nail the throttle.
mcobb2
ArboristSite Operative
That's EXACTLY the thought that went through my head... Although I was taught a 441C-m pulls 12 cu/ft or air a minute at full power. That's impressive in my eyes.
Adirondackstihl
Flyz, Fuel & Fotos
Mark, isn't your hack ported 441 doing the same thing?
mcobb2
ArboristSite Operative
No it's doing it whether it has idled for .2 seconds or a minute. Keep it off the idle and life is bonerific.
Adirondackstihl
Flyz, Fuel & Fotos
Did spell check help you with that?
mcobb2
ArboristSite Operative
No, you're hott sister did...
Adirondackstihl
Flyz, Fuel & Fotos
Oh
Tell her I said hello
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