Carb tuning

[Daniel VanMeveren]

Got a 441 I'm working on my question is do I set the saw for max rpms with the longest bar I'm running or the shortest I got a 32 on it now tach shows 10250 rpms I know I'm low just dont want to blow it up when I put my shorter bars thinking 13250 no load

 

[backhoelover]

Most set by ear. Listening for it to 4 stroke at top no Load. I set with a tach. Ccw-is richer, cw- is leaner

 

[Joshua Tabora]

Ideally you'd tune to each bar and chain combination, but most don't carry a tachometer in the field. Tune to the shortest bar if you're worried. This will make it so that the saw is running below rpm spec when you're on a longer bar. You can almost always set the high jet rpms right to the manufacturer spec, if not a tad above.

 

[Ted Jenkins]

The bar the chain the RPM are comletely irrelevant. There are many factors that indicate good or marginal performance, but they are only part of the whole picture. The longer the bar the tighter the chain will create a little more drag on the engine, but not relavant. What matters is when the saw is cutting with full load on the engine what is happening in the combustion chamber. Is it lean rich or just right. There are many threads here that discuss proper engine tuning technique. Most describe four stroking then slightly lean the adjustment so that when the engine is under full load the engine is getting a goood ratio of oil and fuel. Pulling the spark plug is essential. I was using some Yamalube the other day because I was given a few gallons of the stuff. After mixing about 34:1 my saws were not running just right so pulled my plugs to find my mixture was on the lean side. To my surprise I needed to richen the fuel mixture to make them purr. So in other words the OP needs to understand what it takes to keep their saw tuned to perfection. Or pay no attention and contact some one here for a complete rebuild. Thanks

 

[Daniel VanMeveren]

Ideally you'd tune to each bar and chain combination, but most don't carry a tachometer in the field. Tune to the shortest bar if you're worried. This will make it so that the saw is running below rpm spec when you're on a longer bar. You can almost always set the high jet rpms right to the manufacturer spec,

 

[Daniel VanMeveren]

Thank you for your advice I greatly appreciate it have a good day

 

[Matt93eg]

I quit using a tach. I tune in the wood by ear by listening to the saw 4 strone

 

[Joshua Tabora]

I quit using a tach. I tune in the wood by ear by listening to the saw 4 strone

Tuning by ear works for a lot of people, and it's certainly effective. However, I think it's pretty intimidating, especially for someone worried about blowing up a top end. Better to let him learn how his saw cuts/sounds when adjusted to factory spec than to damage a cylinder trying to learn to tune by ear. Just my 2 cents.

 

[buzz sawyer]

fwiw, a 34:1 mix is leaner than a 50:1 mix. 34:1 is more oil, less fuel.

 

[Tinman204]

I tune by ear in the wood.

I like a good 4 stroke out of the wood and listen for the motor to clean up in the cut.

I also perfer my saws a bit on the rich side as I'd rather have my saw last forever then get a few tenths of a second faster cut in the wood.

 

[Matt93eg]

I have nothing against a tach per say. It wasn’t very long ago I didn’t know how to tune by ear. I studied it and listened a lot and now prefer my ear and never get a tach out.

In the beginning I know what your saying but in the end however I think tuning in the wood by ear is actually safer than a tach. By knowing what your listening for you know at all times how the saw is doing mixture wise and can make “on the fly” adjustments easier than getting the tach out.

Like I say I have nothing against a tach, but I quickly moved past using one myself and now solely tune by ear.

On my older saws I find it much easier to hear the 4 stroking. My 390XP is a bit harder but a lot easier after the muffler mod and I also find that wearing ear plugs makes it way easier to hear also.

And I do the same as tin man. I don’t set my saws on the ragged edge. I set mine to 4 stroke instantly if I let off the load.

 

[Ted Jenkins]

What is so difficult about looking at the spark plug. They do not lie. A rich chocolate brown will not burn up, but a light gray will. After 50 years of experience I still pull the plug now and then. It is a for sure sign as to what is going on inside. Thanks