MS200T bogging down when warm

[Paddy1000111]

44 minutes ago, Darkslider said:

I think I left it on 2 turns out on the H screw as that was where it seemed happiest, it was running and revving up nicely at that whereas any less and it would cut out if the revs were left to drop. Perhaps I should have given it another 1/4 turn on the L screw too, it seemed to be inconsistent I thought I'd fixed it as it was idling and revving nicely for a period but then it cut out and was a pig to start again so I carried on tweaking.

 

I've had to hand it back as it is and admit defeat as it's needed tomorrow, but i checked the needle seat while the carb was off and I couldn't blow through it while it was held shut by the spring so I don't think that's the reason for it flooding, the 'tang' had a slight bend in it that would have limited how much the float needle could open too would have been interesting to compare that to a new one and see if that's the shape it's meant to be or if it's been modified in the past. Also checked the impulse pipe was still on the airbox, filters and lines clear with no holes, compression was 150 psi after a few pulls-all the normal stuff. 

 

It's had plenty of use so a bit of blow by isn't unlikely, when it does run it has loads of power reportedly. I'll try and get some feedback on how it does this week, if it's no good it could be coming your way ?

 

The arm on the fuel inlet valve should be flush iirc from the Zama c1q rebuild manual. You should be able to put a straight edge across the carb body and that arm should just touch it. 2 turns out on the H screw sounds like a lot to me though?

 

"place a straight edge or Zama Z gauge across the carburetor body. The free end of the metering lever should be 0 to 0.3 mm – 0 to 0.012″ below the straight edge"

Edited November 15, 2020 by Paddy1000111

[Darkslider]

On 15/11/2020 at 20:23, Paddy1000111 said:

The arm on the fuel inlet valve should be flush iirc from the Zama c1q rebuild manual. You should be able to put a straight edge across the carb body and that arm should just touch it. 2 turns out on the H screw sounds like a lot to me though?

 

"place a straight edge or Zama Z gauge across the carburetor body. The free end of the metering lever should be 0 to 0.3 mm – 0 to 0.012″ below the straight edge"

 

I might try and get it back in that case to see how far off it is, there was a noticeable bend in the end of the lever back towards the carb which would have had the effect of limiting the fuel needles opening, perhaps in a previous attempt to combat rich running but as I had no way of telling if it was meant to be like that I left it alone. 

[Darkslider]

On 15/11/2020 at 19:44, Darkslider said:

I think I left it on 2 turns out on the H screw as that was where it seemed happiest, it was running and revving up nicely at that whereas any less and it would cut out if the revs were left to drop. Perhaps I should have given it another 1/4 turn on the L screw too, it seemed to be inconsistent I thought I'd fixed it as it was idling and revving nicely for a period but then it cut out and was a pig to start again so I carried on tweaking.

 

I've had to hand it back as it is and admit defeat as it's needed tomorrow, but i checked the needle seat while the carb was off and I couldn't blow through it while it was held shut by the spring so I don't think that's the reason for it flooding, the 'tang' had a slight bend in it that would have limited how much the float needle could open too would have been interesting to compare that to a new one and see if that's the shape it's meant to be or if it's been modified in the past. Also checked the impulse pipe was still on the airbox, filters and lines clear with no holes, compression was 150 psi after a few pulls-all the normal stuff. 

 

It's had plenty of use so a bit of blow by isn't unlikely, when it does run it has loads of power reportedly. I'll try and get some feedback on how it does this week, if it's no good it could be coming your way ?

 

Thought I'd best update, put a Chinese carb on as a bit of a cheap test and it fixed all the problems,  saw now starts, idles and revs as it should, used it to cut some hardwood logs and it didn't miss a beat. It doesn't seem to have much adjustment though so I think a genuine carb is going to be the best option but the Chinese ones are cheap enough to try out to make sure it fixes the problem before splashing out on the real deal.

[Paddy1000111]

12 minutes ago, Darkslider said:

Thought I'd best update, put a Chinese carb on as a bit of a cheap test and it fixed all the problems,  saw now starts, idles and revs as it should, used it to cut some hardwood logs and it didn't miss a beat. It doesn't seem to have much adjustment though so I think a genuine carb is going to be the best option but the Chinese ones are cheap enough to try out to make sure it fixes the problem before splashing out on the real deal.

Carburettor C1Q-S126A for Stihl MS200T MS200 - 1129 120 0653 | L&S Engineers

WWW.LSENGINEERS.CO.UK

---

Carburettor C1Q-S126A Genuine Stihl Part OEM Part No. 1129 120 0653 Suitable for the following Stihl Machines: MS 200 T...

 

That's the one I fitted to mine, Spud has said before, the one with the accelerator is the best 

[Darkslider]

5 minutes ago, Paddy1000111 said:

Carburettor C1Q-S126A for Stihl MS200T MS200 - 1129 120 0653 | L&S Engineers

WWW.LSENGINEERS.CO.UK

---

Carburettor C1Q-S126A Genuine Stihl Part OEM Part No. 1129 120 0653 Suitable for the following Stihl Machines: MS 200 T...

 

That's the one I fitted to mine, Spud has said before, the one with the accelerator is the best 

Cheers mate bookmarked! 👍

[spudulike]

That's the first aftermarket carb I have ever known to work, every one I have seen on MS200s has been utter

$£ite!

The 020 carbs are OK but as they get old, they get unstable. The accelerator pump carbs are my preference as they are very stable but...become less so if the accelerator pump wears....but it can be repaired!

[Darkslider]

1 hour ago, spudulike said:

That's the first aftermarket carb I have ever known to work, every one I have seen on MS200s has been utter

$£ite!

The 020 carbs are OK but as they get old, they get unstable. The accelerator pump carbs are my preference as they are very stable but...become less so if the accelerator pump wears....but it can be repaired!

I haven't used an MS200t before so couldn't tell you if it was making all the power that it should, just that it started, revved and idled ok after whereas it wouldn't before. I didn't pick the cheapest one I could if that has any relevance, I think I'd feel more comfortable if it had a genuine carb put on before long though in case the chinky goes out of adjustment. 

[Paddy1000111]

2 hours ago, spudulike said:

but it can be repaired!

Out of interest have you seen many where the bore has been destroyed? I read about the bore being ruined not just the replaceable bits?

[spudulike]

Only by people blanking the accelerator pump off with epoxy. My supplier has pumps with the O ring in the middle so it is contacting a different area than the Stihl one so it probably helps.

The Chinese carbs generally need almost zero turns on the L screw and whatever the H screw needs to get the revs right.

The last one I tried to tune I was using the L screw to adjust the idle it was that bad.

If you cant get a tune on a saw within 1-2 mins then there is something wrong IMO!