MS290 Tuning/DTI Tiny Tach

[rubin585]

This morning I had the good fortune to test out my new DTI Tiny Tach. Pretty cool. Got readings with only 1 wire wrap and no ground attached!!

Anyhow, I did attach the ground wire and wrap the red wire about 3 times around the spark plug wire. Seems my idle was set pretty close to where it should be. My high speed, on the other hand, showed 14,000 rpm!! This doesn't surprise me, as the saw seemed to be screaming the last couple times I used it. In any event, I have two questions:

1) I used the old drywall screw trick to remove the limiter screw. Even though it was buggered up, I managed to get the limiter cap back on. Is this good enough?

2) I noticed with the limiter cap off and the screw driver still in the high speed screw, the high speed/end seemed to be a pretty erratic, varying about +/- 1000 rpm. Once I got it close and put the limiter cap back on, the rpm was much more stable (+/- 50 rpm). Is this normal?

Thanks in advance for the responses. I think this small investment just saved my saw from premature failure.

 

[anlrolfe]

I think that when they went to limiter caps they ditched the springs and washers that used to hold the needle in place. Not sure if it wobbles around without the limiter cap in place but that would be my first guess. Second guess would be that the limiter cap seals around the needle and keeps in from sucking little bit of air. Some people have to cut the tabs on their limiters to get the mix, was that your case?

 

[rubin585]

I've owned the saw since new. No mods to the limiter caps.

 

[z71mike]

1) yes
2) yes, it could happen