MS 200T - Another Carb and Idle Question

[jpan]

Afterthought, before you rip it all apart set the H and L to 1 turn out and tell me how it runs?

impulse line looks to be connected to the intake boot as far as what I can see from up under the handle.

Set H and L back to 1 turn out. Fires up super easy and idles fine initially. Throttle it and it falls on its face and dies out unless I throttle it slow. Then if Let it idle again and it starts revving and racing then just keeps running fast until I blip the throttle. Only way to get it to calm down is to throw more fuel at it.

 

[grizz55chev]

impulse line looks to be connected to the intake boot as far as what I can see from up under the handle.

Set H and L back to 1 turn out. Fires up super easy and idles fine initially. Throttle it and it falls on its face and dies out unless I throttle it slow. Then if Let it idle again and it starts revving and racing then just keeps running fast until I blip the throttle. Only way to get it to calm down is to throw more fuel at it.

Vac leak, take a better look at the impulse.

 

[lone wolf]

impulse line looks to be connected to the intake boot as far as what I can see from up under the handle.

Set H and L back to 1 turn out. Fires up super easy and idles fine initially. Throttle it and it falls on its face and dies out unless I throttle it slow. Then if Let it idle again and it starts revving and racing then just keeps running fast until I blip the throttle. Only way to get it to calm down is to throw more fuel at it.

Did you try turning the LA screw counter clockwise? If that don't help do a vac test on the saw.

 

[jpan]

Did you try turning the LA screw counter clockwise? If that don't help do a vac test on the saw.

I did. And it idled fine but then revved and raced until I blip’d the throttle then when it idled again it would start to rev on its own.

I’ll tear it down and do a vac/pressure test next.

 

[lone wolf]

I did. And it idled fine but then revved and raced until I blip’d the throttle then when it idled again it would start to rev on its own.

I’ll tear it down and do a vac/pressure test next.

I wonder if the throttle linkage is bent or the butterfly is a tad out of whack ? Does it stall or just keep running? When its off is there any slack in the throttle or does it seem too tight? Is the lever on the carb resting on the LA screw or is it too tight like linkage is bent?

 

[jpan]

I wonder if the throttle linkage is bent or the butterfly is a tad out of whack ? Does it stall or just keep running? When its off is there any slack in the throttle or does it seem too tight? Is the lever on the carb resting on the LA screw or is it too tight like linkage is bent?

I can confirm that the linkage is all working properly and not hanging up l.

 

[lone wolf]

I can confirm that the linkage is all working properly and not hanging up l.

Best to vac test now.

 

[grizz55chev]

Best to vac test now.

The carb boot May just have a tear or the fit on the cylinder may not be tight, it’s only held on by that white rectangle piece.

 

[lone wolf]

The carb boot May just have a tear or the fit on the cylinder may not be tight, it’s only held on by that white rectangle piece.

Easy enough pull on the top handle up and down when running and see if it has an effect. But a full vac test will be best anyways. A ripped boot is usually accompanied with worn or broken rubber mounts as a clue.

 

[jpan]

Best to vac test now.

just did a vac and pressure test. Passes both just fine using the impulse line and blocking off the intake boot and exhaust. I made a block off plate with rubber seal for the exhaust and had a plug that fit in the throat of the intake boot perfect. Holds 7.5psi pressure and same vacuum. Even held vacuum turning flywheel over by hand. Inside of piston and cylinder look almost brand new as well.

This likely point to a bad carb?

 

[lone wolf]

just did a vac and pressure test. Passes both just fine using the impulse line and blocking off the intake boot and exhaust. I made a block off plate with rubber seal for the exhaust and had a plug that fit in the throat of the intake boot perfect. Holds 7.5psi pressure and same vacuum. Even held vacuum turning flywheel over by hand. Inside of piston and cylinder look almost brand new as well.

This likely point to a bad carb?

Yes prob the carb ,usually is.

 

[lone wolf]

Is that a Farmertec top handle on that saw or OEM does it have the thumb switch function positions painted in orange on the top or are they missing?

 

[stihl86]

just did a vac and pressure test. Passes both just fine using the impulse line and blocking off the intake boot and exhaust. I made a block off plate with rubber seal for the exhaust and had a plug that fit in the throat of the intake boot perfect. Holds 7.5psi pressure and same vacuum. Even held vacuum turning flywheel over by hand. Inside of piston and cylinder look almost brand new as well.

This likely point to a bad carb?

Yes. A carb can give strange problems that aren't in any repair manual. Many tree services I deal with prefer the 200T over a 201T. They are very wrong but at any rate, I have a new carb I'll just slap on, then test. Most of these saws have lived their usable life and have paid for themselves 20x over. Your buddy probably knows that. You should be able to get an OEM carb for about $75.00. The list is right around that.
Double check initial; settings, then double check your work.
Your starting to chase your tail.

 

[jpan]

Is that a Farmertec top handle on that saw or OEM does it have the thumb switch function positions painted in orange on the top or are they missing?

believe oem. Markings painted in orange.

 

[jpan]

Yes. A carb can give strange problems that aren't in any repair manual. Many tree services I deal with prefer the 200T over a 201T. They are very wrong but at any rate, I have a new carb I'll just slap on, then test. Most of these saws have lived their usable life and have paid for themselves 20x over. Your buddy probably knows that. You should be able to get an OEM carb for about $75.00. The list is right around that.
Double check initial; settings, then double check your work.
Your starting to chase your tail.

Dealer quoted $75 for carb so I’ll go that route. Everything else seems ok pressure and vac wise

 

[lone wolf]

believe oem. Markings painted in orange.

OK then prob the carb. As long as the linkage isnt binding.

 

[jpan]

OK then prob the carb. As long as the linkage isnt binding.

everything seems to be moving freely and not binding or catching anywhere. When idling it will be idling normal then all the sudden rev and star revved without even touching it. I’ll get a carb this week and hopefully that takes care of it

 

[lone wolf]

I

everything seems to be moving freely and not binding or catching anywhere. When idling it will be idling normal then all the sudden rev and star revved without even touching it. I’ll get a carb this week and hopefully that takes care of it

I suppose it is the carb but we wont know till you try one. Only other thing it could be is an airleak that is sporadic! Did you wiggle the crank ends and the impulse line while testing? Also it would be interesting to put that in a bucket of water while under pressure just for kicks.

 

[jpan]

I

I suppose it is the carb but we wont know till you try one. Only other thing it could be is an airleak that is sporadic! Did you wiggle the crank ends and the impulse line while testing? Also it would be interesting to put that in a bucket of water while under pressure just for kicks.

I can try that. Any issues with the coil and everything getting submerged?

Mira just odd to me because I’ve never had a small engine carb that itself air leaked but I suppose everything is possible

 

[lone wolf]

I can try that. Any issues with the coil and everything getting submerged?

Mira just odd to me because I’ve never had a small engine carb that itself air leaked but I suppose everything is possible

No problem submerged. Wiggle all areas that could leak.