Video: How to tune a chainsaw

[mtfallsmikey]

Excellent Brad! Thanks.

 

[whitedogone]

There's more to tuning a chainsaw than just adjusting the high end, but this is a start. It also gives an excellent example of what 4-stroking sounds like.

In the first cut, the saw continues to 4-stroke, even towards the bottom of the cut. That's a little too rich. It should run clean all the way through the cut once under load.

After that first cut, I tune the H screw. I turn the H screw in clockwise until the engine peaks out and is totally 2-stroking. No 4-stroke at all. I then quickly richen the mixture back up by turning the H needle counter-clockwise. Immediately you hear the engine begine 4-stroking again.

The next cut you can hear the engine immediately clean out once underload, and stay that way for the entire cut. After that cut I rev the saw and you can hear that it is still 4-stroking at WOT. It's important to check for that after a cut, since that's when your saw will be its hottest and leanest.

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I'll try to make a more detailed tuning how-to video that includes L and LA adjustments.

I can't hear that

 

[mtfallsmikey]

I can't hear that

I had to back the video up a couple of times to hear it...just for a split second when Brad blips the throttle after adjustment/ 1st cut.....

 

[whitedogone]

the last cut is where I can't make it out.

 

[bytehoven]

Absolutely. That's about where'd I'd want it for a tank or two.

Brad...

Have you posted an expanded video for tuning L LA? I searched but did not see.

Thanks

RJ
...

 

[oceancruze1]

There's more to tuning a chainsaw than just adjusting the high end, but this is a start. It also gives an excellent example of what 4-stroking sounds like.

In the first cut, the saw continues to 4-stroke, even towards the bottom of the cut. That's a little too rich. It should run clean all the way through the cut once under load.

After that first cut, I tune the H screw. I turn the H screw in clockwise until the engine peaks out and is totally 2-stroking. No 4-stroke at all. I then quickly richen the mixture back up by turning the H needle counter-clockwise. Immediately you hear the engine begine 4-stroking again.

The next cut you can hear the engine immediately clean out once underload, and stay that way for the entire cut. After that cut I rev the saw and you can hear that it is still 4-stroking at WOT. It's important to check for that after a cut, since that's when your saw will be its hottest and leanest.

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I'll try to make a more detailed tuning how-to video that includes L and LA adjustments.

No come down on me being an amateur. What exactly does 4 stroking mean? The sound of a two stoke engine running as if it was a 4 stroke running smoothly??

Carl

 

[blsnelling]

Brad...

Have you posted an expanded video for tuning L LA? I searched but did not see.

Thanks

RJ
...

There's an example of it in the 3120 Gone Wild thread.

 

[bytehoven]

There's an example of it in the 3120 Gone Wild thread.

Gracias!

 

[LazyJ]

Even if I owned a tach I would still fine tune by this method. What's the comparison of this in the cut method to a tach tune, generally richer or leaner?

 

[blsnelling]

Even if I owned a tach I would still fine tune by this method. What's the comparison of this in the cut method to a tach tune, generally richer or leaner?

Tune it in the wood, record that RPM, and then you can duplicate that with your tach.

 

[PHobbes]

Thanks for the Vid! My 029 is running like a champ now!

 

[rmihalek]

Different Strokes

No come down on me being an amateur. What exactly does 4 stroking mean? The sound of a two stoke engine running as if it was a 4 stroke running smoothly??

Carl

I believe that an overly rich mixture loads up the plug, so the engine is not able to fire on every stroke. Hence, it may fire on every other stroke (like a 4 stroke) or even worse, every third stroke, etc. Make it too rich and the plug will foul.

 

[Stihlofadeal64]

I take it that at WOT even after the cut that you're not that concerned about the MAX RPM's at this point, but more with the sound of the 4 stroke at top end. Am I right to assume this or am I missing something. (I indeed can hear the 4 stroking, but was wondering if -500 or -700 off the top end with a tach would be the same thing?). Can you elaborate? Thanks! I enjoyed the video.

 

[blsnelling]

I take it that at WOT even after the cut that you're not that concerned about the MAX RPM's at this point, but more with the sound of the 4 stroke at top end. Am I right to assume this or am I missing something. (I indeed can hear the 4 stroking, but was wondering if -500 or -700 off the top end with a tach would be the same thing?). Can you elaborate? Thanks! I enjoyed the video.

Tune it in the wood, as shown, the use your tach to see what RPMs it's turning. You can then use that as a reference point.

 

[powerking]

Great Job Brad!! I'm making popcorn now and waiting for the entire "saw tuning" collection of vid's!!!
Rich

 

[JustinM]

brad, excellent video!

 

[blsnelling]

Glad I could help.

 

[kirkeg]

I was wondering if i got that tune right - thanks blsnelling

 

[Dan_IN_MN]

No come down on me being an amateur. What exactly does 4 stroking mean? The sound of a two stoke engine running as if it was a 4 stroke running smoothly??

Carl

I believe that an overly rich mixture loads up the plug, so the engine is not able to fire on every stroke. Hence, it may fire on every other stroke (like a 4 stroke) or even worse, every third stroke, etc. Make it too rich and the plug will foul.

This sounds good........can anyone confirm? I've also been thinking about what is going on when the engine is "4 stroking" or "fluttering".

I just found this tread and thought it was so good that I put a link in my sig.

 

[kgb007stb]

Great post on the four stroke tuning, I could not distinguish between the WOT four stroking after the final cut, could have been my computer speakers.

My biggest problem was deciding at what point should the four stroking go away, on my 55 rancher that has a gutted exhaust it goes away at around ¼ load on a sharp chain and always four-strokes after being pulled out of a cut at WOT. Tach specs at 12,200 altitude 1475 feet.

Pulling out of a long cut, is it better to back off and then check at WOT for four-stroking? I usually end up pulling out of a cut at WOT when checking for four-stroking as some loggers told me that backing off even for a shot time causes a change in the mixture and engine temperature drop.

Just curious on the L side do you check by the “roll test” to see if the saw is loading up on unnecessary fuel in the crank case?