Tachometer........ Buy One Or Not???

[excess650]

I finally broke out the new tach

http://www.amickssuperstore.com/DTI...chometer_Tach_p/dti tech-tach tt-20k tach.htm

and used it today. I had bought a used 272xp, and it was way out of tune. I did get it running half decent by ear, but the tach sure shows how far off things can be. Anyway, after letting the saw idle to warm up with fresh 40-1, I fooled with the low speed mixture and idle. After it seemed close, I tuned for max revs, and could get ~13,600. I richened the high speed mixture back to 13,000, and then fooled with the low speed and idle, and then back to the high speed until I was satisfied, leaving it at 13,000.

Having read that you should tune with your shortest bar, I had 20" on it. Since this saw is going to be tried on the mill Saturday, I mounted the 28", and just for S&G, I put the tach on it to see how many revs it would lose. It GAINED 600 rpm! I tuned it back to 13,000 and called it good.

I feel better with the tach!

 

[psquared]

Longer bar higher speed??

I finally broke out the new tach

http://www.amickssuperstore.com/DTI...chometer_Tach_p/dti tech-tach tt-20k tach.htm

and used it today. I had bought a used 272xp, and it was way out of tune. I did get it running half decent by ear, but the tach sure shows how far off things can be. Anyway, after letting the saw idle to warm up with fresh 40-1, I fooled with the low speed mixture and idle. After it seemed close, I tuned for max revs, and could get ~13,600. I richened the high speed mixture back to 13,000, and then fooled with the low speed and idle, and then back to the high speed until I was satisfied, leaving it at 13,000.

Having read that you should tune with your shortest bar, I had 20" on it. Since this saw is going to be tried on the mill Saturday, I mounted the 28", and just for S&G, I put the tach on it to see how many revs it would lose. It GAINED 600 rpm! I tuned it back to 13,000 and called it good.

I feel better with the tach!

Did you experiment with the chain tension on the 28 inch bar?

Why would the speed go up with a longer chain. I have not done the speed comparison ( yet) with different bar lengths but you got me curious.
:chainsawguy:

I'd be betting on a drop in RPMS.

 

[excess650]

Did you experiment with the chain tension on the 28 inch bar?

Why would the speed go up with a longer chain. I have not done the speed comparison ( yet) with different bar lengths but you got me curious.
:chainsawguy:

I'd be betting on a drop in RPMS.

Both bars and chains were NEW. The 20" had loosened a bit by the time I was done tuning, but the 28" might have been too tight if anything.

 

[psquared]

Did you use peak RPM or watch the direct readout. I got some funky spikes on peak hold mode with my 361 so I think continuous mode might be better.

I just got the tach also and haven't done much experimentation.

 

[excess650]

Did you use peak RPM or watch the direct readout. I got some funky spikes on peak hold mode with my 361 so I think continuous mode might be better.

I just got the tach also and haven't done much experimentation.

I was watching the readout.

 

[LazyJ]

I just experiened the same circumstance, went from a 20" bar turning 13,400 to a 28" I just bought today and thought I'd check it again for grins... 13,600. I'm was kinda thinking it had more to do with air temperature, it was 105 the day I tuned it with the 20 and it was 82 today when I checked it with the 28 bar. Same mix, same filter condition, nothing changed but the bar and temp. Maybe a new bar/chain runs faster?

 

[Ghillie]

For those of you that found this thread searching for "fluke tachometer" ...

the fluke 88 automotive only reads up to 9999 rpm!

 

[Taxmantoo]

For those of you that found this thread searching for "fluke tachometer" ...

the fluke 88 automotive only reads up to 9999 rpm!

Same deal with my Ferret 86 timing light.