WHSH
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Hi,
I have ported a few saws with 210 plus psi and the most recent is a Dolmar 5100s with 215psi. My questions is what are the symptoms at idle of a saw that has too much or high compression issues. I run 93 oct, amsoil saber 50:1 and startron. The dolmar has this funky idle along with some of the other saws I that i have ported. All the saws have monster power. Its like it skips a stroke and then fires off two right behind each other. When the saw starts and is cold it does not do this, when it worms up it gets more pronounced. It sounds like "ding, space ding ding, space ding, space ding ding" This Dolmar has incredible torque in hard wood. You would break the mounts before you could bog it down. I tried something different with this saw. It was the 14.5k motor that had the reputation of blowing up. I removed the base gasket, 045", cut the piston crown down , no squish band cut, no pop up. Final squish is .025. I did not change the port timing other than the piston cut and the base gasket removal. This would retard the timing, wich I wanted for a 13k high rpm. From my math and observations the cumulative movement of the port timing down retarded the exhuast by 2 degrees about .020" lowering of the exhaust window. I have tried more mix oil, jetting high and low with some effect. Any one if this is cause by high compression. I can gasket the cylinder up if I need.
I have ported a few saws with 210 plus psi and the most recent is a Dolmar 5100s with 215psi. My questions is what are the symptoms at idle of a saw that has too much or high compression issues. I run 93 oct, amsoil saber 50:1 and startron. The dolmar has this funky idle along with some of the other saws I that i have ported. All the saws have monster power. Its like it skips a stroke and then fires off two right behind each other. When the saw starts and is cold it does not do this, when it worms up it gets more pronounced. It sounds like "ding, space ding ding, space ding, space ding ding" This Dolmar has incredible torque in hard wood. You would break the mounts before you could bog it down. I tried something different with this saw. It was the 14.5k motor that had the reputation of blowing up. I removed the base gasket, 045", cut the piston crown down , no squish band cut, no pop up. Final squish is .025. I did not change the port timing other than the piston cut and the base gasket removal. This would retard the timing, wich I wanted for a 13k high rpm. From my math and observations the cumulative movement of the port timing down retarded the exhuast by 2 degrees about .020" lowering of the exhaust window. I have tried more mix oil, jetting high and low with some effect. Any one if this is cause by high compression. I can gasket the cylinder up if I need.
