Thanks for the thread Carl.
Is the Coil limited?
Other than weight Joe, how do you see the windowed piston helping? It's gonna push charge around cylinder extension and up through the case fed lowers.
Carl, how are the tunnels looking vs. the 490? Are they bigger and do they make a less abrupt turn into the cylinder?
These saws seem to not sell after all this work. I listed my 490 complete with warranty at my cost with no labor or consumable charge since May. It's just sitting.
@WSE15 showed a tach pic of 14,700 said it just ran out of fuel.
Doubt it is a limited coil, if it is that extra 1000+rpm is gonna be beneficial on this size saw anyway.
When I seen the piston on the ipl, figures for sure it was a center fed quad jug. Wondering if the piston is any lighter at all? full size pin, seems plenty thick around the windows.
Don't really see the windows helping much with the way this jug is..
Transfer tunnels /outlet look really similar to the 590. without the relief on the lower tunnels or the stagger.
590 really like a symmetric opening. from the wash pic posted, it does not appear the secondary has much flow once the small primary opens.
Feel it will really pickup opening flat or 2* stagger, think more than that is killing secondary flow.
I'm am wondering if they ramp the secondary up so much to help blow burnt gasses out to make room for the power making gasses
That can also backfire, with enough pressure the fresh charge can "cut" through the burnt gas and exit the cylinder. leaving a bunch of already but gas to mix with fresh charge in the chamber.
Echo is not above the epa here. They have to come up with ways to pass the "sniff" tests without going strato. Have a feeling that is the reason for such plugged up mufflers, coupled with less burnt gas being expelled. Makes it easier to pass the emissions. Just my take on what they trying to do.
