Naked Arborist
Hack from way back.
Good call on the intake boot. It is a common problem on MS200T. GL
No power when cutting with top of bar
- Thread starter asgeist
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asgeist
ArboristSite Lurker
Thanks for all the input. You've given me some good ideas of what to look for. Here's an experiment I want to try over the weekend. Let me know what you think. Put a C-clamp on the bar, half-way between the grooves and back from the nose several inches. Tie a rope to the C-clamp in such a way that it's unlikely to get caught by the chain. Start up the saw, and with full throttle, step on the rope and lift the saw so as to put pressure on the bar downward. This way, there's no pressure on the chain, but the bar only. If the engine slows, it has nothing to do with the chain or bar. If the engine doesn't slow, then it is chain or bar or interaction between the two.
If that feels like it's going to be too dangerous, then I could simply remove the chain but put the bar back on chainless. Then do the experiment above, but just putting pressure on the bar directly with my hand.
If that feels like it's going to be too dangerous, then I could simply remove the chain but put the bar back on chainless. Then do the experiment above, but just putting pressure on the bar directly with my hand.
Fish
Tree Freak
A coomon problem is the fuel line developing cracks right around the area where it enters the tank, just pull the line out a tad to check it.
tallfarmboy
ArboristSite Guru
Just leave the saw idle and put pressure on the top of the bar like you would cutting, any speed up in RPM would point right at the intake boot or possibly fuel lines. Steve
I think that I like the 'no-chain' version, but with a tweak: instead of pressing down on the bar with your hand, I would hold the chain-less bar up against a solid object. This way your hands will be in the same position as when cutting. If, in fact, the deflection of the bar is opening up some cracks in rubber parts, as some people have speculated, you want your hands in the same position so that the stresses will be the same.
Chain tension can vary slightly with bar pressure, so the no-chain version eliminates this as an issue, in addition to being safer.
Another option is to try the saw with another (preferably new) bar.
Interesting problem. We are all waiting to find out the source.
Philbert
Chris-PA
Where the Wild Things Are
This is interesting. My McCulloch RedMax GZ4000 clone did this to some extent too. I've changed chains and I'm not sure it's been as noticeable lately, but then recently I noticed a broken rear A/V mount. Once I have that fixed I'll pay attention to the undercut power issues again.
It never made any sense to me and there are some good viable explanations in this thread.
It never made any sense to me and there are some good viable explanations in this thread.
millbilly
ArboristSite Guru
asgeist
ArboristSite Lurker
Original submitter to this thread here.
I did the experiment (chainless, for safety), and I as I thought it might be, it was very illuminating. Even without a chain, the saw slowed way down with enough down-pressure on the bar. So I took it back into the workshop, opened it up, and started looking around an fiddling with things. And I'm pretty sure I found the problem. With the vibration isolation system, wherein the handles are mounted to the rest of the chassis through some springs and bushings, when that down-pressure is applied to the bar, the engine pivots down and away from the handles, and most importantly down and away from the throttle trigger. When it goes far enough, the throttle linkage retracts away from the throttle lever on the carburetor, and behaves exactly as if I've removed my finger from the throttle trigger. My only problem is, I can't see how it ever worked! One of the previous posters said that he had the same problem due to a worn motor mount. (I think he/she gets the prize.) Maybe that's the same problem I've got, but I can't see anything visibly wrong with those mounts, at least not those readily visible. Is there one or more that are buried? How would you recognize a worn mount? And please do NOT say, "When you loose power when applying down-pressure on the bar." You loose points for being a wise-ass!
Thanks again for all the help. You guys have been great!
Asgeist
I did the experiment (chainless, for safety), and I as I thought it might be, it was very illuminating. Even without a chain, the saw slowed way down with enough down-pressure on the bar. So I took it back into the workshop, opened it up, and started looking around an fiddling with things. And I'm pretty sure I found the problem. With the vibration isolation system, wherein the handles are mounted to the rest of the chassis through some springs and bushings, when that down-pressure is applied to the bar, the engine pivots down and away from the handles, and most importantly down and away from the throttle trigger. When it goes far enough, the throttle linkage retracts away from the throttle lever on the carburetor, and behaves exactly as if I've removed my finger from the throttle trigger. My only problem is, I can't see how it ever worked! One of the previous posters said that he had the same problem due to a worn motor mount. (I think he/she gets the prize.) Maybe that's the same problem I've got, but I can't see anything visibly wrong with those mounts, at least not those readily visible. Is there one or more that are buried? How would you recognize a worn mount? And please do NOT say, "When you loose power when applying down-pressure on the bar." You loose points for being a wise-ass!
Thanks again for all the help. You guys have been great!
Asgeist
Thank you for the follow up. That is not something I ever would have suspected, but it is exactly why I participate in A.S. - to learn!
Sorry that I do not have a 'quick fix' for you, other than keeping you chain sharp and cutting close to the engine to reduce the amount of down pressure applied. But I will continue to follow the thread to see if anyone else has some solutions.
Very interesting issue.
Philbert
Sorry that I do not have a 'quick fix' for you, other than keeping you chain sharp and cutting close to the engine to reduce the amount of down pressure applied. But I will continue to follow the thread to see if anyone else has some solutions.
Very interesting issue.
Philbert
OK, just thinking out loud: When the saw is in it's 'normal' position, is there any 'play' in the throttle? Do you have to pull it a little for the wire to engage the throttle plate? If so, could this wire be shortened (make it a hair trigger) so that there is still some range of motion when the saw is flexed?
Other than that, maybe tie some some dental floss to the throttle so you got a second trigger to pull with your teeth . . . .
Philbert
cobey
Addicted to ArboristSite
can u bend the linkage to tighten the throttle a little? i would guess worn holes where the linkage hooks in?
TermiteBuffet
ArboristSite Guru
Hate I missed this thread,I had one in for the same thing in the summer, change all your av springs and you should be good also behind the recoil cover toward the tank is a place you can add one of the rubber types to stiffen even more if you so desire, seems like I did stretch the linkage some to. Best of luck termite
Sent via the computer in my 562xp
Sent via the computer in my 562xp
