Ongoing MS 200T Carburetor Issue

[HandLogger]

I started a thread last summer entitled "Need Help With Adjustment Instructions," which dealt with difficulty adjusting the carburetor on an MS 200T we own. After not being able to successfully complete the adjustment procedure, the saw was placed on the shop shelf and there it sat. We have a little spare time right now, so I've pulled the saw off of the shelf and am attempting to actually remove the carburetor from the saw.

Although we have an Owner's Manual and Parts Diagrams (1129) for the saw, we don't have anything describing service and/or repair work. At this point, I'd like to remove the carburetor from the saw to either remove or modify the "Cap" -- Illustration L (Carburetor C1Q-S61) Page 13, Ref ID 25 -- that limits the rotation of the "High speed adjustment screw" -- Illustration L (Carburetor C1Q-S61) Page 13, Ref ID 24.

If anyone actually has the page from the applicable Service Manual that describes carburetor removal, we'd be much obliged if you would attach a .pdf here. If not, I'd appreciate some words about any tricks involved with the removal procedure. I've had the handle apart in the past, for cleaning purposes, so I'm not really nervous about the linkage and/or the electrical connections (ON/OFF switch). What I am skittish about, on the other hand, is the actual connection between the carburetor and the engine.

If you're familiar with the MS 200T, you probably know that there's a rubber "Cover" -- Illustration G (Handle housing MS 200 T) Page 9, Ref ID 28 -- between the saw body and the handle housing, which, although I'm sure it has an important purpose, serves to shield one from being able to see the intake manifold/boot between the carburetor and the engine.

Here are the Parts Diagrams I've referred to above: MS 200T Parts Diagrams

Thanks for your time ...

 

[lone wolf]

Not hard take air filter cover off
air filter out
2 nuts that hold the air filter base off and the black plastic base
take the gas line off the left side bottom off carb off by pushing it down

pull the carb up and out remove the throttle and choke linkage rods left and rt.
That should be everything you may just have to take the rubber cover off on thr rt. side by the needle jets to get clearance.

 

[HandLogger]

Thanks (again) for the advice, Lone Wolf.

I've got the carburetor off now, and I'm looking closely at how the "Cap" I mentioned in the original post was designed. The Cap is made of plastic and has a protrusion on it that hits a steel post when it's rotated far enough. I'm not sure if the steel post serves any other purpose, so I'm hesitant to modify it in any way. It's shown on Page 13, Illustration L (Carburetor C1Q-S61) as part of the main carburetor body.

I've also tried simply pulling the Cap off of the high speed (H) adjustment screw with pliers, but it seems very happy where it is.

Has anyone on the forum board ever cut the steel post in question to free up the high speed adjustment screw?

If not, how have you dealt with making this particular modification?

Thanks for your time

 

[MCW]

Hi Handlogger.
I've experienced the dreaded 200T carby problems too but in my case a whole carby replacement to an older, non compensating version solved that.
Please find link to workshop manual. It's 7.59MB so just click on the link below and hit "download".
Hope it helps out mate

Zippyshare.com - Stihl 200T workshop manual.pdf

 

[Brian13]

If you havnt looked through this this may help a little too.
http://www.arboristsite.com/chainsaw/145024.htm

 

[HandLogger]

Thanks to MCW and Brian for paying it forward.

MCW: I'd love to read more about your carburetor swap. Are you happy with the performance the new carburetor gives you?

The Chinese (ZAMA) mess I have on this saw has eaten up way too much of our time. If you happen to have a source and a part number, I'd be much obliged to you for the information.

Have a good one :msp_thumbsup:

 

[MCW]

Thanks to MCW and Brian for paying it forward.

MCW: I'd love to read more about your carburetor swap. Are you happy with the performance the new carburetor gives you?

The Chinese (ZAMA) mess I have on this saw has eaten up way too much of our time. If you happen to have a source and a part number, I'd be much obliged to you for the information.

Have a good one :msp_thumbsup:

Hi mate. No dramas for the help.
I didn't actually do the swap but one of the local Stihl dealers did. They did the mandatory epoxying of the accelerator pump etc but the saw continued to get out of tune, over rev etc etc. It was really running like a pig. Anyway I took it back in to the dealer and he replaced the carby and backing plate to an older setup he had in his workshop for free. It has not missed a beat since He told me that my issues had him stumped and he works on a lot of 200T's. They are a very popular saw here for fruit tree pruning and contract pruning companies.

I'll try to get some pictures and more information up ASAP.

 

[MCW]

Back again.
Just pulled down both my recarbed 200T and my brand new one in the cupboard.
The non compensating backing plate you'd need is part # 1129 120 3400 and looks to be from the older 020 and 020T. I found a few listed here on eBay...

NEW STIHL AIR FILTER BASE EARLY 020T, 020 T CHAINSAW PART # 1129-120-3400 | eBay

The carby is a ZAMA S16A non compensating version the same (or similar to) as this one...

ZAMA Carburetors C1Q-S16A fits Stihl 020T, 1129 120 0601 | eBay

The code stamped on the carby is S16A 3YR. I "think" the above two parts are all you'd need?

Below are a couple of photos of my new 200T's carb setup...

And my older, fixed 200T which used to have the same setup as the new one...

Plus piccys of the older carby...

Hope that helps. The 200T's are one of the best saws on the planet when running properly but the biggest pigs when they get carby trouble!

 

[HandLogger]

Identification

Cheers for the photos, Matt.

I've already modified and reinstalled the carburetor on my MS 200T, so I need to ask a question before I go through the trouble of pulling the saw apart again. I see that there's a cast mark on the side of your old carburetor that seems to read S10? It's in the photo that shows the side with all three adjustment screws. Is that the number one should look for to identify which model came on the saw?

The carburetor we have looks a lot like the one shown on Page 13 of our parts's diagram: MS 200T Parts Diagram.

As you can see, Stihl is calling the carburetor a C1Q-S61. I understand that there were quite a few variations on the Zama Chinese carburetor, so I think it would be wise to educate myself about which model we actually have before we go any further.

Here's a photo I took while I was working on the saw. As you can see, it seems to identify the saw as an S61D. Considering that the carburetor depicted on Page 13 of the MS 200T Parts Diagram seems to match, I'm thinking that our saw's carburetor is indeed a C1Q-S61D.

View attachment 220378

Here's a look at the backing plate we have on our saw as well. I noticed that the hoses and such on your saws seem to be a bit different than ours. Any words of wisdom are greatly appreciated.

View attachment 220380

 

[MCW]

Cheers for the photos, Matt.

I've already modified and reinstalled the carburetor on my MS 200T, so I need to ask a question before I go through the trouble of pulling the saw apart again. I see that there's a cast mark on the side of your old carburetor that seems to read S10? It's in the photo that shows the side with all three adjustment screws. Is that the number one should look for to identify which model came on the saw?

The carburetor we have looks a lot like the one shown on Page 13 of our parts's diagram: MS 200T Parts Diagram.

As you can see, Stihl is calling the carburetor a C1Q-S61. I understand that there were quite a few variations on the Zama Chinese carburetor, so I think it would be wise to educate myself about which model we actually have before we go any further.

Here's a photo I took while I was working on the saw. As you can see, it seems to identify the saw as an S61D. Considering that the carburetor depicted on Page 13 of the MS 200T Parts Diagram seems to match, I'm thinking that our saw's carburetor is indeed a C1Q-S61D.

View attachment 220378

Here's a look at the backing plate we have on our saw as well. I noticed that the hoses and such on your saws seem to be a bit different than ours. Any words of wisdom are greatly appreciated.

View attachment 220380

I'm all out of wisdom now What you have is the compensating carby by the look of it so to get a non compensating setup like mine you'd be looking at the items I linked to. Both of the 200T's I have are US sourced so shouldn't have been any different to yours. As mentioned the Stihl dealer was the one who rebuilt everything but I am pretty certain that the non compensating backing plate and the non compensating Zama carb will sort you out. The tank breather setup has just been left to "hang" in the middle and hasn't been mounted like the newer setups. There is a small chance that the non compensating carby may have been NOS and Australian market specific but I doubt it.
I hope that isn't as clear as mud

The model number on my non compensating carby didn't show up under flash but it is located here inside the red circle. This is where "S16A 3YR" had been stamped into the alloy...

 

[HandLogger]

It's all helpful

What do they say a picture's worth, Matt? Cheers again.

I'm not a Stihl repair tech, so I guess there's really no shame in asking: What in the hail is a "compensating" carburetor?

I'm assuming that it's a way to compensate for air loss -- as in when the filter starts to clog up --but I'm not sure about that. If my guess is good, however, the compensation feature of the carburetor in this particular saw never worked very well. In fact, this saw never ran well when the filter got dirty.

Here's another photo of the saw's carburetor. Is there anything here that shows more about the type of carburetor we have?

View attachment 220425

 

[MCW]

What do they say a picture's worth, Matt? Cheers again.

I'm not a Stihl repair tech, so I guess there's really no shame in asking: What in the hail is a "compensating" carburetor?

I'm assuming that it's a way to compensate for air loss -- as in when the filter starts to clog up --but I'm not sure about that. If my guess is good, however, the compensation feature of the carburetor in this particular saw never worked very well. In fact, this saw never ran well when the filter got dirty.

Here's another photo of the saw's carburetor. Is there anything here that shows more about the type of carburetor we have?

View attachment 220425

Hey there isn't any shame in asking about what a compensating carby is. I had to ask the dealer about it myself a while back when he fixed it. You are exactly right though - as the filter blocks the pressure differential across the filter changes the tune as far as I am aware. Smart concept and it really is an excellent feature when working well but probably better suited to homeowners who have never heard of the word "maintenance". I have seen homeowner Stihl models with this feature that shouldn't even be running but were and still running well.
The photo you've attached of your current carby doesn't tell me much except that it's a compensating type If you pull the couple of nuts and take the carby out it should have a model on it somewhere. They ARE the carbies that can cause grief though, I know that much. I can't remember the member here who was a Stihl Tech but there were certain models of compensating carbies worse than the others. I just can't remember which ones he said

 

[HandLogger]

Still Reading ...

I'm still reading everything I can about this problem, Matt, but one thing's for sure. The carburetor on the saw I'm working on is a Zama C1Q-S61D 434A.

I'm taking the saw back to the woodlot tomorrow, and I'll post about how that turns out. With any luck, having the [new] ability to turn the high-speed adjustment screw (H) will allow me to finally tune the carburetor. From what I've read, however, this particular carburetor can be a major league headache.

 

[MCW]

Good luck and keep us posted for sure Once they're running properly there is no better saw in my book. Not one single saw I have owned has paid for itself faster than my 200T...

 

[HandLogger]

I Think It's Carb Time!

Okay, so I took the saw back to the woodlot today and attempted to adjust the Zama C1Q-S61D 434A that's the subject of this thread. I followed Page 32, Adjusting the Carburetor, as published in our MS 200T Instruction Manual, and, to make a long story a bit shorter, I was unable to get the saw to run smoothly. In short, the saw idles much too fast and the engine bogs when the trigger is squeezed. Yes, the saw starts and runs consistently now, but it runs like what the dog leaves on the lawn.

So it's looking like carburetor (carb) replacement time. I've read quite a bit about how these Zamas can be modified and/or repaired, but I simply don't have the time to spare right now. When I get the time, I'll buy a kit and take a crash course in Zama carb repair, but, for now, I'm looking for the fastest route.

We would rather invest our hard-earned in a better carb than the S61D, obviously, so I'm looking for suggestions from the AS.com membership. It was suggested, earlier in this thread, that we give a backing plate and a non-compensating carb (C1Q-S16A) -- both originally designed for an 020T -- a try, but there's really no way for me to verify whether or not this option will require modification to the choke and/or the accelerator linkage. Judging by the photos of the older carb setup, the linkage looks different to me.

Other than replacing the defective carb with another C1Q-S61D, are there any other "bolt-on" carburetors available for the MS 200T? If anyone has been in the same situation and is sure that the carb they employed is a direct replacement, we would greatly appreciate a part number.

Thank you for your time

 

[lone wolf]

Handlogger here is the part number for the new carb 1129 120 0653
What mounting plate does yours have the one with the hole for the little snorkel on the rt side?If so you are good to go.

 

[HandLogger]

C1Q-S169 Carburetor

Thanks very much for the part number, Lone Wolf.

I looked into the part number and, as far as I can tell, it crosses to the Zama C1Q-S169 carburetor (carb).

How long have you been running this particular carb in your 200T, Lone Wolf?

Do you know whether or not it has the accelerator pump that apparently causes so many 200Ts to run poorly [or not at all]?

I didn't get the part number in time to call our nearest Stihl dealer, but I will as soon as I can.

I really appreciate the help.

 

[MCW]

I'll leave you in the capable hands of Lone Wolf Handlogger. I know from his previous posts on the 200T that he knows his stuff and will be of great help I reckon
Good luck with it all and I can't honestly say if the linkages are different or not. The dealer only told me he changed the carb and backing plate, no mention of linkages but that's not to say they weren't changed.

 

[lone wolf]

Handlogger can you send pics of the carb box area?

 

[HandLogger]

Carburetor Air Box Area

MCW: No worries. You mentioned having your "new" carburetor installed by a dealer, so I knew there was no way for you to know whether or not anything had to be modified to accommodate the non-compensating carb in your saw now, the Zama C1Q-S16A 3YR. Thanks for helping out. I wouldn't know what a compensating carb is, otherwise.

Lone Wolf: I checked into the Stihl part number you gave me for a replacement carb -- 1129 120 0653 -- and the result was a dealer price of $95.70 (without sales tax). Obviously, this is yet another reason to be sure about which carb we should buy to replace the P.o.S. Zama C1Q-S61D 434A that's currently strangling this particular MS 200T. I also understand that you've been using the carb you recommended -- the one identified in the first sentence -- for more than six months. Considering that you run so many MS 200Ts, I'm sure that you put your new carb through its paces.

Here are the photos of our MS 200Ts air box area, as you requested, Lone Wolf:

And here's one the air box side of the C1Q-S61D 434A