Use tach to adjust factory saw?

[WoodLoon]

Whew! I read to learn and end up more confused. I did some reading here to learn more about adjusting the carb on a chainsaw. Husky says:

1. open the L & H screws one turn from the seat as a starting point,
2. warm up the engine,
3. adjust idle to 2500-2800 w/ T screw,
4. set L screw to 1/4 turn out beyond mid-point between in (lean) & out (rich) point where RPMs start to drop,
5. adjust idle to 2500-2800 w/ T screw,
6. re-check L screw adjustment,
7. adjust H screw so max no-load speed is 12,500 or less,
8. repeat L & H adjustment if necessary

Use any tachometer that reads from a spark plug? Any suggestions for a tach?

In other posts, I've read about adjusting the carb so it just starts to fourstroke and then richen it slightly. But I think you can only do this if you have an unlimited coil.

1. What does it mean, when the engine starts to fourstroke?
2. Do you use a tach if you have an unlimited coil?
3. How do you know if your saw (or my saw, a 1985 Husky 50 Special) has an unlimited coil?

My 25 year old son has been dialing in my Husky 50 by "ear." Now I need another piston and we need to learn a better way!

I also read that I can use any compression gauge that uses a schraeder valve. Any other required or preferred characteristics? Short connecting tube?

I've read numerous mentions of the squish measurement. Is squish the distance between the top lip of the piston and the top of the cylinder wall? How do you measure squish?

And then some of you use special or no base gaskets?

Thanks

 

[SkippyKtm]

Whew! I read to learn and end up more confused. I did some reading here to learn more about adjusting the carb on a chainsaw. Husky says:

1. open the L & H screws one turn from the seat as a starting point,
2. warm up the engine,
3. adjust idle to 2500-2800 w/ T screw,
4. set L screw to 1/4 turn out beyond mid-point between in (lean) & out (rich) point where RPMs start to drop,
5. adjust idle to 2500-2800 w/ T screw,
6. re-check L screw adjustment,
7. adjust H screw so max no-load speed is 12,500 or less,
8. repeat L & H adjustment if necessary

Use any tachometer that reads from a spark plug? Any suggestions for a tach?

I use the Tech Tach TT20K I like it (you don't need to use the supplied clips, just hold it near the plug wire)
http://www.amickssuperstore.com/DTI_2_Cycle_Two_Stroke_Tachometer_Tach_p/dti%20tech-tach%20tt-20k%20tach.htm

In other posts, I've read about adjusting the carb so it just starts to fourstroke and then richen it slightly. But I think you can only do this if you have an unlimited coil.

You can do it with the limited coils too, but you need to check it under a load("in the wood").

1. What does it mean, when the engine starts to fourstroke?
   
   

   The engine is firing on every other stroke like a 4 stroke does.

2. Do you use a tach if you have an unlimited coil?
   

   Yep.

3. How do you know if your saw (or my saw, a 1985 Husky 50 Special) has an unlimited coil?
   
   

   On Huskys the unlimited coils are black, while the limited coils are blue, yours is probably black.

My 25 year old son has been dialing in my Husky 50 by "ear." Now I need another piston and we need to learn a better way!

Here's a good link on saw tuning:
http://www.madsens1.com/saw_carb_tune.htm

I also read that I can use any compression gauge that uses a schraeder valve. Any other required or preferred characteristics? Short connecting tube?

I have an Actron Gauge (Sears) and plenty of spare schraeder valves -they go bad from time to time.

I've read numerous mentions of the squish measurement. Is squish the distance between the top lip of the piston and the top of the cylinder wall? How do you measure squish?

I use solder either stuck in place with 4 dabs of grease or if the saw is toghther i put it through the exhaust port.

And then some of you use special or no base gaskets?

Yep, sometimes no base gasket, just some moto seal or I use aluminum from a coke can, its about 4 thousandths.

Thanks

Welcome to AS! Answers are in Red, links are in Blue...

 

[SawTroll]

Remember that the 12,500 max refer to one specific saw model, and will be different with many other models.

 

[FeTTT]

Old thread, but i need to clarify something...

It pretty clear that a tach can be handy to find the max setting for the H screw and LA screw.

But, does a tach can be used to perfectly ajust the L screw? Does it make sense?

 

[T0RN4D0]

Nope i don't see a way to do it. But L isn't too hard, just aim for snappy throttle response. And you can't mess up the saw with L as easily.

 

[mweba]

Skippy speaks for the saws :msp_biggrin: