About 4 stroking

[Vintage Engine Repairs]

 

[Patrick1903]

Great video. Concise and to the point. Thanks as usual for your video tutorials. As soon as YT promotes this you’ll have a million views.

 

[Vintage Engine Repairs]

Great video. Concise and to the point. Thanks as usual for your video tutorials. As soon as YT promotes this you’ll have a million views.

Haha still waiting for YouTube to get a move on with that LOL.

cheers mate

 

[president]

Not exactly right. You want it to 4-stroke at full throttle as soon as you take the load off the engine and clean up again as soon as you load it down again. 4-stroking at idle is no indication of correct high speed adjustment.

T1

 

[Old2stroke]

T1

That response of mine that you quoted was for an earlier part of this thread where the OP was claiming the 4-stroke at idle was a good indication of proper high speed tuning and doesn't apply to this video. The chap in this video is following one of the popular ways of tuning the high speed by holding the throttle wide open and setting the H screw for 4-stroking at max rpm, not at idle. It is a good demonstration of how to do this and it is the technique that most of the shops use as it's quick and easy and can be reasonably accurate when done right, if you don't mind running an engine at max rpm without a load. I prefer the added accuracy of tuning by the sound of the engine, but you need a log to cut up and few shops have anything they can cut, thus the popularity of the WOT method.

 

[Brufab]

That was a great, easy to understand, straight to the point video. Thanks for sharing it.

 

[Vintage Engine Repairs]

That was a great, easy to understand, straight to the point video. Thanks for sharing it.

Pleasure mate, thanks for the kind words.

 

[chainsawredeemer85]

So if you can only

The term is used as the sound of the saw while idling and warmed up and being used to cut. It's about the high speed setting adjustment. In tuning the carb, one would set the low speed adjustment first...just ever so slightly rich. This would be while at normal idle. Then you set the high speed while saw throttle is wide open (WOT)...Turn it clockwise (lean) until you get a high smooth rev...then turn it back counter clockwise just until you hear it change to a slight "gurgle" sound that is referred to as "four-stroking". It's not real smooth as when it was at high revving. Again, it is being set just ever so slightly rich. Now you turn the screw back toward clockwise (lean) until the carb just clears out again.
Now if you did this correctly...when you pull saw out of a cut and drop saw back to idle it will again "gurgle-four stroke"--but when you start another cut the carb will clear back out and rev smooth but is still set on the rich side.
The high speed needs to be set rapidly as you don't want to be holding the saw at WOT while not in a cut but for only a few seconds!!!!!!

This will explain it perhaps better for you than I did....

http://www.madsens1.com/saw carb tune.htm


J2F

So if you can only run the saw a "few seconds at WOT do you feel it is bad for an auto tune or mtronic to be ran WOT for 90 seconds straight?

 

[Vintage Engine Repairs]

So if you can only

So if you can only run the saw a "few seconds at WOT do you feel it is bad for an auto tune or mtronic to be ran WOT for 90 seconds straight?

It’s full throttle but not full rpm on m-tronic reset. Totally different.

 

[bwalker]

It’s full throttle but not full rpm on m-tronic reset. Totally different.

Full rpm won't hurt a saw at all...

 

[bwalker]

That response of mine that you quoted was for an earlier part of this thread where the OP was claiming the 4-stroke at idle was a good indication of proper high speed tuning and doesn't apply to this video. The chap in this video is following one of the popular ways of tuning the high speed by holding the throttle wide open and setting the H screw for 4-stroking at max rpm, not at idle. It is a good demonstration of how to do this and it is the technique that most of the shops use as it's quick and easy and can be reasonably accurate when done right, if you don't mind running an engine at max rpm without a load. I prefer the added accuracy of tuning by the sound of the engine, but you need a log to cut up and few shops have anything they can cut, thus the popularity of the WOT method.

Four stroking isn't just slightly rich. It's rich to the point the engine is misfiring..

 

[Vintage Engine Repairs]

Full rpm won't hurt a saw at all...

 

[bwalker]

View attachment 1122554

Stihl says alot of things. Calculate the piston speed and get back with me.

 

[ElevatorGuy]

Holy thread revival batman!!!! I ain't seen this thread in years........ Its funny seen an old post revived. Keep up the good work and keep them saws tuned!!!!

Bullittman

Best part is the op never came back 8 days after his post.