Saw not idling

[gary112]

Could be the carb Chuck i had similar thing with a cheap carb on a strimmer. put a good un on and runs perfect 

[Stretchsaws]

37 minutes ago, chuck norris said:

I dunno, it was not replaced in the rebuild. I will take it out and check, for damage.

 

Pot and piston are oem, but the carb is not. Do you recommend replacing the carb?

 

Is there a way I can check, for an air leak without doing a vacuum test? I just really don't really fancy, buying something I will only use once

That's a fair point, the Stihl vac/pump kit was around £200! But I picked up a Bluepoint one for £90, which is a bit better.

One method to check is to get a can of carb cleaner with a long nozzle and whilst the saw is running,  carefully spray in areas where air leaks could appear I.e around intake manifold, impulse line, base gasket etc. However, the saw needs to run first and you can get false readings if any spray gets sucked into the carb!

Your saw sounds like it's a fuel delivery issue rather than an air leak, so I'm not trying to lead you off on a tangent.

[spudulike]

Spraying carb cleaner around the manifold condenses the fuel and causes the machines idle to change even on a healthy machine. This is down to the carb cleaned taking heat away from the manifold to evaporate the solvent and basically turns the vapour back to fluid! Better to roll some light oil around the areas.

OEM cylinder - good, aftermarket carb....can be good or bad. I have seen these on MS200s and have had to modify the throttle valve to get them to work anything like the standard unit and was pretty poor TBH.

Personally I would either rebuild the original carb or purchase a new/second user OEM one and try that.

A bad air leak will cause the saw to rev out but not idle well. Try moving the L screw out 3-4 turns and if you then get some sort of idle then it is probably a bad leak but if it does nothing, you most likely have a carb issue, Making the L screw super rich sort of counteracts the air leak but is NOT a solution, just a diagnostic tool!

After doing this sort of thing a bit, the machines sort of tell you what is going on through their behaviour!

[billpierce]

What is wrong with old carb? Can you try it on old carb? Or take the gaskets and diaphrams out of new and put on old one?

[Stretchsaws]

7 minutes ago, spudulike said:

Spraying carb cleaner around the manifold condenses the fuel and causes the machines idle to change even on a healthy machine. This is down to the carb cleaned taking heat away from the manifold to evaporate the solvent and basically turns the vapour back to fluid! 

I agree, like I said it can give false readings. Which is why I wouldn't rely on it at all, however it was useful to me once out on site at a customer's when they asked me to look at their erratic running 026, so that's why I mentioned it. 

Also, I agree that it sounds like a carb issue, and was not trying to send the fellow off down the garden path, just trying to help.

[billpierce]

What non own carb was it? I have had a few farmertec ones on a 361 and 200 for a good few years no probs......

[chuck norris]

So an update. I have inspected the impulse line and carb boot, and they both look fine. I have also put it through some wood, and I found that it has very little power no matter how much I fiddle with the h screw. So I have come to the conclusion, that it is a carb issue.
The reason I believe it is not a air leak is that in my experience, an air leak will cause the saw to race before dying, but my saw just dies as if you turned it off.

[Stretchsaws]

I suspect you're correct, there are so many variables with chainsaws, more so than other 2-strokes in my opinion. There's chain, bar, type of wood (or plastic..go figure) being cut, fuel, carb, tank vent, hoses, mating surfaces, gaskets etc. etc. That's why I love em I guess, the challenge. Hope you get to the bottom of your issue.

 

 

 

 

[spudulike]

On ‎05‎/‎11‎/‎2017 at 10:07, Stretchsaws said:

I agree, like I said it can give false readings. Which is why I wouldn't rely on it at all, however it was useful to me once out on site at a customer's when they asked me to look at their erratic running 026, so that's why I mentioned it. 

Also, I agree that it sounds like a carb issue, and was not trying to send the fellow off down the garden path, just trying to help.

I wasn't having a pop so apologies if it looked that way. I once wasted many hours on a 039 carb spraying it and getting nowhere but it can help especially on the clutch side seal if it is leaking. 

[Jiles]

On ‎11‎/‎5‎/‎2017 at 02:48, chuck norris said:

I dunno, it was not replaced in the rebuild. I will take it out and check, for damage.

 

Pot and piston are oem, but the carb is not. Do you recommend replacing the carb?

 

Is there a way I can check, for an air leak without doing a vacuum test? I just really don't really fancy, buying something I will only use once

Send me a PM --I may have a suggestion

Edited November 9, 2017 by Jiles
added words