stihl 361 running backwards

[guym3]

I recently bought a non-running ms361 in fairly good condition. Replaced the ignition coil with after market and have MM'd it, base gasket delete and ported it. Have had some carburation issues but is running fairly well. But... Sometimes when I start it, it runs backwards. I've heard of this and understand that 2stroke ports don't care what direction they run in, but not sure how it works with a coil firing before TDC. I've never seen this happen though and wonder if anybody can enlighten me on what might be causing it?
thanks

 

[Canadian farm boy]

Did you advance the ignition timing?
Has the FW slipped on the crank?
From my experience with the 361 they don’t like much advance if any. Could also just be the aftermarket coil

 

[guym3]

Thanks. No I haven't taken the flywheel off and it doesn't look as though anybody played with it before. I didn't intend to advance the timing as I know they generally don't benefit. I might get a timing light and see where it's actually set.

 

[jacktheripper]

Very cool. Keep it and use for cutting upside down.

 

[Stihl036]

Is the bar on upside down?


(I'm kidding)

 

[Stihlbro]

I know of a 361 that has done it a few times. All oem parts. Stock saw. If it starts on a short rope pull, it could run backwards. Sounded normal but chain wouldn’t cut. Shut it off, restarts and rotates normal. It never does it on starts when more rope is pulled out of recoil.

 

[Woodwackr]

Very cool. Keep it and use for cutting upside down.

So, send it to Australia?

 

[guym3]

Interesting observation. Short pull..... yes it was that. I'd modified a 460 carb to fit but it would only run for a few seconds. I discovered that the main jet wouldn't hold a vacuum so swapped out for an oem Zama carb. It was on a short pull and did it twice.

Would be interesting to put the chain on. backwards and see how it would then cut.

 

[GMB74]

I built an MS361 saw-in-a-box (Chinese spare parts kit). Did a base gasket delete which gives it a lot of compression and resistance when pulling it over to start. Mine will run backwards on startup sometimes. I figured it was a combination of the aftermarket coil and not giving it a stout enough pull when starting. No big deal, shut it off and restart it, runs fine otherwise.

 

[guym3]

Thanks, that's reassuring. I've got probably 15 other chainsaws all with gasket deletes (so high compression) and most AM coils but this is the only one that does the whole backwards thing. Sounds as though its not a serious fault, just wondered what it is about the 361 which makes it do that?

 

[IffykidMn]

Interesting observation. Short pull..... yes it was that. I'd modified a 460 carb to fit but it would only run for a few seconds. I discovered that the main jet wouldn't hold a vacuum so swapped out for an oem Zama carb. It was on a short pull and did it twice.

Would be interesting to put the chain on. backwards and see how it would then cut.

May be useful for top bar cuts with a pulling chain.

 

[Woodwackr]

Hm, I have one in a box to build…gonna have to watch for this

 

[gorilla]

Well thanks a lot you bunch of chuffs, I bought a couple of 064s where the seller said they were running backwards, and I got a weeks worth of everyone completely taking the p,ss out of me. However..I searched this forum and then removed the flywheel keys put in some random coils and timed the pair with the flywheel 1/4 to 1/2 " higher than the north magnet at TDC, and I had a couple of raving monsters. I sold one and use one .. so well done OPE

 

[guym3]

Thanks Gorilla. I can imagine the 064 running backwards after it is so keen to rip your arm off when you don't pull it over fast enough. I'll look out for mine doing that.
Suspect I'm being thick but can you explain what you did to the flywheels and timing to prevent this. Didn't really understand.

 

[gorilla]

I just used a coil I had and one for an 026, pulled the flywheels off and removed the woodruff keys, then aligned the top magnet on the flywheel about a quarter of an inch above the coil, and bang, I was so lucky both worked fantastically well first time. I have no timing light or any other way of testing stuff. Just lucky I recon

 

[guym3]

Oh I get it. Thanks

 

[EFSM]

It doesn't surprise me that this discussion has centered around Stihls. Their coil timing at startup is not nearly as retarded as some other brands, making this a lot more likely. I does seem like it could loosen the clutch or flywheel, if run too long.

 

[Wilhelm]

It doesn't surprise me that this discussion has centered around Stihls. Their coil timing at startup is not nearly as retarded as some other brands, making this a lot more likely. I does seem like it could loosen the clutch or flywheel, if run too long.

Starter paws hung up...

A couple of my 46/50cc Dolmar saws like to start up reverse.

 

[Wilhelm]

And my 50cc throwing fits

 

[guym3]

Interesting. Watching it nudge the chain as you pulled it, about half were forward and half back. Seemed to have little preference. Thanks for sharing.