MS200T bogging down when warm

[htb]

Steve, You need to join the Spanish inquisition.

[BrucetheSpruce]

Yep, owned from new, 2010/11 I think.
Has sat in the garage the last 5 years.

Was pretty careful to not force too much resin into the two small holes behind Welch plug as read that would be a problem but couldn’t say for sure I suppose.

Yes, I think it does but will double check in the morning.

Thanks

[spudulike]

Ah, but nobody expects the Spanish Inquisition! Now where are the soft cushions!!!!

[bmp01]

Yeah, running fine for 20 mins is way into hot running..... anything beyond 1 min of running (under load) is hot. Sounds like plugged accel piston is OK.

Areldite under the welch plug ? ? ? Surely not.....

After 20 mins there's plenty of heat soak, hoses, intake boot, engine mounts all get a bit softer.

Have you tried another quarter turn on the low screw when it misbehaves - might give you a clue if its definitely a fuelling issue.

How long does it need to cool down to then operate correctly ?

 

Edit:

Could be the diaphram or pump in the carb need refreshing after that time sitting around in garage. Just thinking heat soak into the carb is changing their behaviour and therefore the fueling after 20 mins ??

 

 

 

Edited November 11, 2020 by bmp01

[spudulike]

He means the welch plug on the choke back side of the carb covering the accelerator channels not the one over the low speed fuel injector holes in the metering section part of the carb!

[bmp01]

2 minutes ago, spudulike said:

He means the welch plug on the choke back side of the carb covering the accelerator channels not the one over the low speed fuel injector holes in the metering section part of the carb!

TFFT !

[Paddy1000111]

I went through similar issues with mine before I changed the carb and it was due to the H jet leaking back. Sometimes it would be fine, other times it would idle fine then bog on full throttle unless I eased it into it. The H jet on these carbs has a diaphragm non-return valve on them. Due to these saws not having any form of reed valve you get blowback through the carb and it can push air into the H jet if you have a faulty one. 

 

These guys know more than me, but this was my experience. Fitted a new carb and it runs a dream. You can buy a new jet from LS Engineers for a few quid though if it's what you think it is

[bmp01]

12 hours ago, Paddy1000111 said:

Due to these saws not having any form of reed valve you get blowback through the carb and it can push air into the H jet if you have a faulty one. 

 

These guys know more than me, but this was my experience. Fitted a new carb and it runs a dream. You can buy a new jet from LS Engineers for a few quid though if it's what you think it is

True enough. On these engines the reverse airflow is controlled by bottom edge of piston closing the inlet port. You will get a bit of reverse flow. A worn piston will make this worst - which is why Spud says check engine wear....compression test. ....

 

You can check the one way valve in the main jet with the carb on the bench. Take cover and metering diaphragm off, blow and suck through the high speed passageway using a soft piece of rubber tubing, its quite obvious if one way valve is defective. 

[Paddy1000111]

Out of interest when it's bogging, is it bogging after idling a little (over say 3-5 seconds or so) or does it bog straight between cuts? I.e. you let off the throttle, it goes back to idle, you hit wot and it bogs straight away? 

[BrucetheSpruce]

That’s interesting. Not an issue I’ve heard of before. Cheers Paddy

I’ll pay more attention to when it’s bogging and let you know.