UKC

Following on from https://www.ukclimbing.com/forums/t.php?t=659709&v=1 which had been archived :

After cleaning the fuel filter I can suddenly get the motor running. Hooray!
However after chopping a few logs I'm starting to get into trouble again. there's a few issues.

With the choke half out it behaves pretty well. With it all the way in it loses power whenever I pull the trigger.

Other concerns are that the chain runs even when it is idling - a centrifugal clutch issue?

And the chain is blunt which doesn't help anything...

Any advice?
Gte

In reply to G. Tiger, Esq.:

Any advice? Buy a new chainsaw!

In reply to subtle:


Buying pre split and cut firewood might be safer

In reply to G. Tiger, Esq.:


That really does sound like a leak in a fuel line drawing in air.

I'm guessing that you don't need telling what to do about a blunt chain

In reply to G. Tiger, Esq.:

If you leave the choke half-out after starting the saw will run at half-speed which is probably why the chain runs. It could also be too slack.

In reply to G. Tiger, Esq.:
Some crud in the jets in the carb would cause that, take the carb apart, take the jets out and clean them.

In reply to G. Tiger, Esq.:

But cheap but twice?

Follow the above advice regarding fuel lines etc. After your dabbling before is everything back in place correctly.. , over reving is why your chain keeps moving.

In reply to G. Tiger, Esq.:

>Other concerns are that the chain runs even when it is idling - a centrifugal clutch issue?And the chain is blunt which doesn't help anything...Any advice?Gte

I had that on my Stihl and got the clutch replaced.....might be a bit of a safety concern if you can't flick the guard to keep it on but stop the chain running.

In reply to Morgan Woods:


Not being able to use the chain brake is the safety concern!

Not only does it protect you from kickback it should also be used everything you move your feet with the saw running.

In reply to timjones:

Are we talking about the same thing ie the big plastic guard thingy ont the front you pull back to stop the chain running (while keeping the engine going)

In reply to Morgan Woods:


Yes, but it's to.prevent the chain running if something goes wrong. It shouldn't routinely be used to stop the chain.

In reply to Morgan Woods:

The centrafugal clutch contracts at low revs, that is what stops drive to the chain. The brake is 100% a safety feature, not a means of slowing the chain.

In reply to summo:

So just to confirm, the chain brake is fine, but the idling revs are clearly enough to engage the clutch and run the chain.

I took the carburettor apart again, and cleared all sorts of crap out of the fuel screen (loads of slimy shiny grey sludge, as well as cleaning the whole lot again.

A new fuel line is ordered and on the way, so hopefully we're getting there.

Any tips on lowering the idling speed?

Gte

In reply to G. Tiger, Esq.:

Yeah. When you rev it the clutch expands and makes contact driving the chain. If the springs or something had broken you would know.

Idle speed . Some saws have two little holes in the side of the casing to adjust carb settings. But I would be surprised if they just went wrong themselves quickly on a relatively new saw. I would just look at the carb area with the top cover off. When you release the choke does everything move inside, it isn't jammed etc.. There isnt a bit of wood or crud stopping it etc.. A blast of wd40 over all the moving throttle cable and parts etc.. Just reassure yourself you are not replacing parts that don't need it.

In reply to G. Tiger, Esq.:


I'd suggest that you don't touch the idling speed until you have sorted the bigger problem.

If it is still too high then there should be a simple adustment screw somewhere that you turn back until the chain stops moving.

In reply to timjones:

This helps to clear up why my chain moved a little bit on my saw when I did my 'small trees' chainsaw test.

In reply to Timmd:


It could be the reason, paradoxically it can also be a bit of fuel "starvation" due to filter or fuel line issues or even just the fuel running low in the tank.

If you were using someone elses saw for a test the idle ought to have been properly adjusted before it was handed to you.

In reply to timjones:

I thought the brake should be used every time you are not using the saw, e.g.when you need to put it down to move a log or cutting. It's what I have been advised by arb specialists.

In reply to blackmountainbiker:


Best to think of it as an emergency stop or parking brake, not a means of slowing the chain. Yes you should apply the brake as you say, but leaving go of the trigger should drop the revs to idle speed and the chain stops on it's own. The brake band won't last long if consistently used to stop the chain.

It's a matter of practice and timing, but if say snedding you should be able to back off the revs Just before the cut is complete, so you never have the saw cutting fresh air at full revs, that's just wasting fuel and oil

In reply to blackmountainbiker:



That's correct IMO, but if the saw is correctly set up the chain should not run without the brake in.

The brake is a precautionary measure rather than something that is routinely used to counteract poor maintenance.

If the saw is well maintained it shouldn't be an issue to switch it off when you put it down.

In reply to timjones:
Agree, my Stihl stops when I back off the throttle, the brake is a safety measure.

In reply to G. Tiger, Esq.:


That begs the question, is there such a thing as a 4 stroke chainsaw? That'd be a formidable machine, if a trifle slow. And heavy.

In reply to jon:

Where I used to work, there was a diesel one!

In reply to jon:

youtube.com/watch?v=E9x8rBKC4BE&

In reply to jon:

I think they are mainly 2 stroke because 2 stroke's will work upside down.

In reply to routrax:


So will 4 strokes if you build them right

In reply to Chris Harris:

My god, what a beast! Ah, Republicans...

In reply to Chris Harris:


Take that mother nature!