Thread: Chainsaw kicks when pull starting

Try this Nick.
Pull the starter three of four times with the switch in the off position and then switch on and start normally.

Originally Posted by Picko

Try this Nick.
Pull the starter three of four times with the switch in the off position and then switch on and start normally.

Thanks for the reply. I will give that a go. But what am I looking for? Will this be trying something, or trying to remedy the problem? The trouble is it happens so randomly, and then maybe thrtid or fourth go it's fine. But at least once I have yanked the saw out from under my foot because of the freeze.

Also, should it be happening?

Is anyone thinking compression/decompression like I am?

Maybe but what aspect of it? My 371XP Husky has a decompression button, which is for cold start use only (and then I assume only because you may have to pull a few times to get it going from cold), but the 32CC husky did not. It did not need it. This 38cc one does not have one and on a good rope pull does not need it. Is that what you mean?

Not trying to rag on you.

If you mean that the saw is sitting compressed (maybe the engine could retain compression for a while??), and I am trying to pull over that, then two things. My 371XP never had that even at new, and the other thing is that if you _do_ pull past it on one engine stroke, it will have another go at sticking, quite often, on that same rope pull. When it's not there it's as smooth as and is far more likely to fire up and go. I am pretty experienced at pull starting nice and smooth (hah! I owned a Poulan and decided that it was called that because you had to poul and poul and poul to start it....it was a real b****h), and I can feel a good start.

This definitely is not just me woossing out on a rope pull.

My main question is still, should this be happening or am I being given the fluff by the dealer?

I think your thread title is confusing. When someone says a chainsaw kicks I think of that as the engine kicking back. This is quite different to a chainsaw "sticking" or "freezing".

If it is sticking then one possibility is that there is something loose in the crankcase that is jamming the piston/crankshaft but seeing as the saw sometimes starts and runs ok(?) then it is probably not that.

If you can't turn over the saw at all then it could be that you need more Weeties for breakfast.

Well actually when I think of kicking I usually mean the chain coming back in my face when the chain tip grabs....;so yeah maybe my title is not right.

I doubt there is anything mechanically loose. As you say it starts OK and runs fine.

I can pull start a 71 CC saw with no compression release, using my thighs to hold it. This is actually a recognised method but you have to have full control of the saw. Enough weeties (well usually eggs actually)

My question remains: has anyone else struck this?

Originally Posted by REALOldNick

Well actually when I think of kicking I usually mean the chain coming back in my face when the chain tip grabs....;so yeah maybe my title is not right.

I call that "Kick back"

I doubt there is anything mechanically loose. As you say it starts OK and runs fine.

Yep

I can pull start a 71 CC saw with no compression release, using my thighs to hold it. This is actually a recognised method but you have to have full control of the saw. Enough weeties (well usually eggs actually)

What about the saw on the ground and the foot partially through the trigger handle?

Reciprocating engines are designed to hold their compression for a measured length of time. Indeed, that is how some engines are initially assessed without tear downs; how long they hold compression for, compression lost versus compression held; but that is digressing.

Not wanting to dwell on the following but I have had a bit of experience with high performance two strokes in the past and one particular japanese engine I was familiar with had a history of frequent but mild seizures. They were so common they were considered not only normal but almost necessary to bed the piston in. I am not suggesting that is the case here but I wonder what things would look like if you took the head/cylinder off; some scoring on the piston walls perchance? Wack her off and have a look; bugger the dealer he's not helping.

Keep it civil please Old Nick.

Hi RealOldNick,
The significant part of your statement is that it does it warmed up but not cold. My opinion is that it is compression. I have experienced this with my chainsaw and 4stroke lawn mower. I used to have a truck with a small V8 Cat diesel engine and sometimes it was a mongrel to start when hot with what appeared to be excessive compression.
Apart from that, perhaps there's something loose in the starting mechanism.
Regards,
Geoff.

I have a Jonsered 2077 similar...but crisp hot or cold, no decompressor...and it can really bite from time to time when it fires before tdc...a mates Oleomac 50 is the same, occationally...I put it down to well oiled rings at that moment on the compression issue....really all it can be...just pull start it like you mean it, every time!

What oil mix are you running

Hi all,

i think i know the feeling, i used to work in a bicycle repair shop in my adolescent years (working on many mopeds and motorcycles as well) and many times i noticed a strange sort of friction while slowly rotating the flywheel by hand as a way to detect any crank bearing play, piston ring scraping or groove damage in piston and cylinder surfaces. All of a sudden there was this point where the piston experienced more friction, like the lubricant was all of a sudden replaced by water , to end up feeling a bit rubbery instead of an smooth sliding action. I also experienced this while testing compressor units and testing chain saws after taking them apart and rebuilding them. I discussed it with others and they knew what i meant, but they all thought it was merely a question of either vacuum or compression buildup. When you listen really close, you should be able to hear some air escape through the thin layer of oil when you try to move the piston through such a section of sudden friction. Large one-cylinder motorbikes like the Yamaha XT 500 can also show this behaviour. One time you can kick as hard as you want and not start it or have the thing kick back at you, the other time is smooth and it starts at once. It's just a question of getting a feel for how to build up the pull or the kick. You may have noticed some riders fiddling a bit with the kickstarter before kickstarting the engine just the right way. You can also try that with your chain saw. Set the piston in a certain position beforehand, than yank the cord real hard and watch what happens.
Large saws like the Stihl 070 have a decompression-valve, you open it and make sure that the piston gathers enough momentum by a huge pull, than let go of the valve to build up just enough useful mix pressure to start up before the rpm's are gone. Small saws indeed do not have such valves, but they don't need one. Just yank thoroughly but try to fiddle around with the best starting position of the piston before you start to pull real hard. As for the retention of compression in the cylinder; that's gone after seconds (20 seconds at best), even with the smoothest of piston rings.

good luck

gerhard

Yes, all the XT and TT500 riders I know used to find compression, lift the valve lever, slowly move the kick starter PAST tdc, release the valve lifter and THEN kick using the engines rotating mass to pass over the next TDC; it was no secret... standard procedure. If you find no broken rings or significant scoring, and I suspect you won't, it will be a compression issue.

Thanks for all the input and sorry for my any hissy fit.

I take on board all the stuff about compression and it makes sense. I am just disappointed that I have had so many saws and other small two strokes, and never had to worry about approaching a start with such care, determination and not a little trepidation. I know that every start should be approached with firmness and the right attitude, but with all other saws I could learn the feel of a start. With this one every one is a crap-shoot. I guess it's about creating too high a compression to max the power for the unit, to make it sell.