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Forgot cp70 wasn't torn down all the way. You can just make out 3 open finger ports though. This seems to differ from the 7-10 and pm700 a bit. Anyone comment on how they run?
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Forgot cp70 wasn't torn down all the way. You can just make out 3 open finger ports though. This seems to differ from the 7-10 and pm700 a bit. Anyone comment on how they run?
View attachment 792665
The "3 finger" is whats in a 10-10. Thats interesting. A pro 10-10 automatic to be precise.
 
The "3 finger" is whats in a 10-10. Thats interesting. A pro 10-10 automatic to be precise.
I thought my early 7-10 had the three finger ports but it's been forever since I looked at it. I'm glad we are documenting all of this, it will be good info for when I get back into mine. I still think I have a piston to cylinder mismatch or something that is effecting the port timing.
I also thought about possible "free porting" from the piston skirt maybe being too short. I will see when I get back to it.
I have to get through some customer work first.
 
I thought my early 7-10 had the three finger ports but it's been forever since I looked at it. I'm glad we are documenting all of this, it will be good info for when I get back into mine. I still think I have a piston to cylinder mismatch or something that is effecting the port timing.
I also thought about possible "free porting" from the piston skirt maybe being too short. I will see when I get back to it.
I have to get through some customer work first.

Really hope ya get going
 
From the land down under comes a new (and more likely) 82cc hp figure - well at least for the PM8200. 5.6 horsepower. Zoom in on this brochure.

https://www.ebay.com/itm/Vintage-Mc...185803?hash=item3b1a5a250b:g:Qg8AAOSwU1hbiyqt

Ron

Good info right there. I thought they'd be closer to 6hp though. Oh well.

HP numbers would be another thing to document here too. With verified sources, like brochures or actual Dyno runs. I was searching info on older 80/87cc Macs earlier and wound up on a vintage karting thread that quoted some old hp numbers from brochures. Highest I saw for one of the old 80cc motors was 5hp, but some models like D30 was 3.9hp.
 
That horsepower figure does not tell the whole story as far as torque goes and how and when that applies.

Yes I agree 100%. Most old Macs have a lot more torque than their modern counterparts. HP certainly doesn't mean everything, it takes torque to get work done. If we could spin them a couple thousand more rpm the HP would be right up there too.
 

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