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!
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!
Anyway you found the problem and all is right. The question now becomes, will they come loose again? time will tell.
