MS200T bogging down when warm

[BrucetheSpruce]

Would anyone be able to help with the above problem I’m having?

 

After recently blocking off the accelerator pump the saw starts and runs sweet so thought I’d fixed the boggy acceleration.

 

I’d previously changed:

Fuel filter

Fuel line

Spark plug

Carb kit and cleaned it

 

Blown out:

Air filter

Fuel tank vent and valve

 

I’d even replaced the fuel cap thinking there was a problem with the pressure...no psssst when opened

 

When it’s boggy it does pick up if I feather the trigger

 

Any advice would be much appreciated. I don’t want a dealer to have it for another 6 weeks

 

[lux]

Would anyone be able to help with the above problem I’m having?
 
After recently blocking off the accelerator pump the saw starts and runs sweet so thought I’d fixed the boggy acceleration.
 
I’d previously changed:
Fuel filter
Fuel line
Spark plug
Carb kit and cleaned it
 
Blown out:
Air filter
Fuel tank vent and valve
 
I’d even replaced the fuel cap thinking there was a problem with the pressure...no psssst when opened
 
When it’s boggy it does pick up if I feather the trigger
 
Any advice would be much appreciated. I don’t want a dealer to have it for another 6 weeks
 

Air leak somewhere maybe.

I had one that only played up when hot. Cylinder and piston were scored.

I’d imagine you’d be better off getting a new saw and chucking the old one in to be fixed and not worry about how long it takes.

[bmp01]

And you've re-tuned the carb ?

 

What did you do to disable the accelerator circuit ? Are you 100% sure its an air tight seal ?

 

[Wonky]

What are the carb settings you’ve set it at ?

 

it could be as someone else has said, you have a air leak and tuned the carb to compensate and it seems fine at wot.

 

or it could be the slight bog you can get after blocking off the accelerator pump. well mine has this, and I’ve had to tune the low a bit rich then I get a big puff of blue smoke if it’s left ticking over for a while.

Edited November 11, 2020 by Wonky
Add “fine”

[Stubby]

I seem to recall when one of mine had the inevitable piston pump issues I had a carb fitted from a much earlier saw that did not have this feature . Or am I dreaming ?  

[spudulike]

No Stubby, you are not dreaming, you had the earlier 020 carb but the issue with these carbs is that old ones with a bit of wear become very unstable and are the bane of my life! Almost as much as those crap Chinese AM carbs that are downright weird to tune and are usually as unreliable!

Disabling the accelerator pump can cause a lag in the throttle response, hey, that is why they fitted the thing in the first place and is the reason that my customers always have a new pump fitted rather than plugging the pump mechanism.

BMP asked how it was plugged and guess he knows what I know may be the issue although if the saw was bogging in the first place and isn't improved, it may not be an issue with the plugging.

The lag may be a multitude of things but the state of the top end has to be the first thing to look at. I am finding a lot of cheap Chinese top ends being fitted to these saws and TBH, most are fit for the bin rather than being used on a primary saw but there you go, you save £60 and live with the consequences!!! 

OP - what is the condition of the top end - compression figs hot and cold after 1 pull and 6 pulls?

 

[Khriss]

Or buy an Echo, like you should  have done in the first place  ?  nice saws. Was this helpful?  I know the answer ? K

[spudulike]

Nothing wrong with 200s, it is just people have high expectations of 10-15 year old saws and feel a £20 new top end will sort out any issues.

My approach is to get them in bits, replace anything worn with OEM parts, rebuild, set up and then test.....pretty simple and have done more than I can remember- must be a thousand or so by now!

I find them remarkably simple to work on but guess others don't judging some of the disasters that I have seen!

[BrucetheSpruce]

Really appreciate the replies...

This is the deepest I’ve got into a saw so really learning as I go. Please be gentle
No idea what wot means and certainly don’t know how to check the top end. The saw is original.

I removed the acc pump applied Aradite epoxy resin and refit. When the bogging reappeared I’d assumed I’d done a crap job and popped the welch plug and filled that area.

The carb is set at H 1 - L 1 1/4

The saw runs spot on for approx 20mins use before the bogging starts but I’ll pay more attention to that when I use it tomorrow.

[spudulike]

WOT = Wide Open Throttle ie flat out!

How do you know the saw is original - have you owned it from new? Post a pic of the plug hole if you haven't, I may be able to tell!

You may have forced resin straight in to the check valve, one of the problems with this repair and not an easy one to sort! 

The time you have to run the saw to produce the problem leads to piston/cylinder wear rather than anything else but difficult to tell. Does it run fine when cold to 15mins?