eugene89us
ArboristSite Member
Good morning, everyone. I noticed on these threads that most folks with Dolmar 5105S or similar saws, like PS-510 and PS-5100, all seem to be running at a higher RPM. My MS 261 Stihl runs at 2800 RPM per Stihl recommendation with high jet at 14,000 RPM.
I have read here that high-speed coil Dolmars can run up to 14,500, but they perform well running between 13,800 and 14,200. For sake of preserving the saw's life, I will probably tune the high jet to run around 13,800-13,900 RPM, that will give me plenty of room for error.
I also understand the process of adjusting L and S screws. For Stihl, the process is easy in my opinion. You raise the RPM with speed screw up to 3300 (500 RPM above recommended), move around the L screw until you find the highest RPM. After that, speed screw drops back down to 3300 RPM, and finally the L screw finishes by enriching the mix back down to recommended 2800 RPM. It sounds complex, but closely follows highly recommended Chainsaw tuning video by Steve's Small Engine channel. He raises speed screw until chain starts to move (which follows Stihl's recommendation to raise the speed first), then he find the sweet spot of highest RPM with L screw, and then he enrichens L screw until the speed JUST starts to drop, and finished with S screw to stop chain from spinning. That is very similar, I think. One is the tach method, the other is the ear method.
What I am not certain about is what should the final idle RPM be at? The manual for 5100 and 5105 says 2500 is the idle RPM. Most folks posting here run around 2900-3000 RPM idle. Is there a specific reason for tuning it to run that fast at idle?
I have read here that high-speed coil Dolmars can run up to 14,500, but they perform well running between 13,800 and 14,200. For sake of preserving the saw's life, I will probably tune the high jet to run around 13,800-13,900 RPM, that will give me plenty of room for error.
I also understand the process of adjusting L and S screws. For Stihl, the process is easy in my opinion. You raise the RPM with speed screw up to 3300 (500 RPM above recommended), move around the L screw until you find the highest RPM. After that, speed screw drops back down to 3300 RPM, and finally the L screw finishes by enriching the mix back down to recommended 2800 RPM. It sounds complex, but closely follows highly recommended Chainsaw tuning video by Steve's Small Engine channel. He raises speed screw until chain starts to move (which follows Stihl's recommendation to raise the speed first), then he find the sweet spot of highest RPM with L screw, and then he enrichens L screw until the speed JUST starts to drop, and finished with S screw to stop chain from spinning. That is very similar, I think. One is the tach method, the other is the ear method.
What I am not certain about is what should the final idle RPM be at? The manual for 5100 and 5105 says 2500 is the idle RPM. Most folks posting here run around 2900-3000 RPM idle. Is there a specific reason for tuning it to run that fast at idle?