Saw idles too fast

[Mingara]

Hi all. My Dolmar 120si idles too fast. It starts okay and appears to run fine until I start cutting. After I let go of the throttle following a cut the saw slows down but still revs high with no throttle. I run the saw on 40:1 mix and have not had this problem before. Any ideas what is making the saw behave like this?

Mingara

 

[Dan Forsh]

How old is it?

 

[SRT-Tech]

sticking throttle linkage, or sticking throttle plate

clean with a shot of carb cleaner.

 

[Mingara]

Dan I don't know how old the saw is beause I ahve only had it a couple of years. Up until this problem I have had no problem with it although it is not used regularly. I use it mainly to cut my firewood off my property.

 

[Mingara]

SRT Tech

Thanks I'll get some carb cleaner and give it a shot. Is this stuff a spray or squirt oil type application.

 

[SRT-Tech]

its the spray. Throttlebody cleaner, carb cleaner, all good. Spray a little on the butterfly valve, in the opening of the carb throat, and any metal linkage parts, wait a few seconds and move the linkage back and forth. Fire it up and see if that makes a difference. Try not to use too much, the carb cleaner is pretty powerful.

hope this works out for you, it worked for me on a Holley 7150 Dominator carb on a custom 500CI bigblock i had in my 78 bronco. the linkage was all sticky and the throttle plates would stick WIDE OPEN THROTTLE! not good.... :bang:

 

[Dan Forsh]

Try the carb spray first as that is far easier and could be the simple answer.

If that doesn't work it can sometime be down to the shaft of throttle butterfly sticking too due to crud or surface corrosion on the shaft. I play with a lot of cut off saws, so I suppose all that masonry/cement dust and no oil allows the problem to occur easier. If you can disconnect the throttle linkage and get your hands on it, try opening and closing by hand to see if you can feel any resistance or sticky spot.

If needs be take the carb off, remove the butterfly and remove the shaft, I tend to spray them with a little WD40 and give em a polish with some 1000 grit wet or dry paper.

This is easy on the TS 350-360 saws as they have big chunky carbs, I can't say how easy it will be on your Dolmar.

Dan

 

[Kneejerk Bombas]

It sounds like an air leak or maybe a tank vent clog.

 

[mattinky]

It could be leaking crank seals