Still MS170 chainsaw hard to start & doesn’t run long

[Burnerman]

This is how I set the idle, or slow running speed screw.
Get the machine running - use the mechanical throttle stop screw to achieve this if necessary, but have the machine running pretty slow - if it allows this!
Turning the idle screw in weakens the mixture.......the engine should speed up but it will have no power when you squeeze the throttle. Turning in too far will cause the engine to stall.
Turning the idle screw out makes the mixture richer.......the machine should start to slow up and maybe there will be a little smoke. Turn the screw back in at that point so the machine just starts to run slightly quicker and that should be it.
I hope this helps, but these carb settings are pretty critical!
John

 

[ipbr21054]

The screw on the carb is left hand thread.
I think you are talking about a normal screw

I am correct or wrong ?

 

[Burnerman]

I sort of remember this odd ball carb......does it have a funny slotted head?
No matter, turning it in weakens the mixture, turning it out riches it again.
Give what I’ve said a try and see what happens.....nothing to lose!
John

 

[ipbr21054]

Yes it’s a slotted screw.
So tomorrow I will get it warm then try in & out until I can rev it with the bogging & chains spinning in bar.

Thanks.

 

[ipbr21054]

So the question I haven’t asked yet is When I try to rev & it bogs down does that mean it’s not getting enough fuel ie I need to turn the idle screw out to make it richer.

Would that be correct.

 

[Burnerman]

It's usually not enough fuel, but unfortunately this syndrome can occur either way, and the machine still bogs down.
Experiment time, I'm afraid!
John

 

[ipbr21054]

Yesterday i started it & left it to run a few minutes to warm up.
I started to turn the screw a 1/4 of a turn & gave it a rev, i did this until i was able to rev without it bogging.
Even though these are a very good copy of the original something internal must be different slightly as i was turning it for a while until it was sweet.
Took the saw to the job where it performed fine & logs all cut up.

Many thanks.

 

[ipbr21054]

So i think the issue is back or just didnt go away.
Same process to start as mention of which i was told is correct.
Using the saw for say 10 minutes & it seems like i need to keep blipping the throttle lever or i think it will stop.
When it does stop i have the lever on the running mark but im pulling & pulling.
I move the lever down to the half choke i think you call it & after a few pulls it starts.
Im then having to rev it when im not cutting to keep it going.
This seems to be the process ive just had to do for the last 30 minutes to complete the job.

So what should i be doing now as to me having choke on makes it richer hence maybe not getting enough fuel.
Having to rev it would also delivery more fuel.

So letting it run on its own i would think its week or not enough fuel for it to continue on its own.

I have the carb which has a left have screw for tick over.
I set this up last week when it was that cold spell so did i do it right ?

 

[ipbr21054]

Just for the record & to save people making a comment suggestion i have replaced the following for its service / possible fix for when it was boggin down.

CARB
SPARK PLUG
AIR FILTER
FUEL FILTER IN TANK
FUEL PIPE IN TANK TO CARBFRESH TANK OF OIL / FUEL MIX

 

[Burnerman]

These machines don't like E10 fuel which is why I only use the Aspen type now. I too have to make regular adjustments on the same machine.......things even seem to change if the sun goes in!
John

 

[ipbr21054]

E10 is 95 RON which is what I use in my car & other petrol tools. I’ve been using it in my tools for a while now & even this MS170

I think I will get it warmed up & then turn that single screw once more a bit at a time now it’s much warmer. Never simple is it.