74" Stroker Pistons
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Joined: Feb 2018
Posts: 78
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From: punxsutawney
After searching more I realize this is a moot point. I can get a new set of 80" cylinders and pistons a lot cheaper than messing around with any hard to find pistons....I'll probably just go that route.....
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Joined: Apr 2018
Posts: 68
Likes: 17
From: No. Brunswick, NJ
A few years back I was running Wiseco 9:1 pistons in my 74" shovel. I wanted to raise the compression ratio above 10:1 but the cost of pistons for the project became too much for the trouble. Someone offered a set of 80" flywheels, which I used, and proceeded to swap over the crankpin, rods, bearings, pinion pin, drive shaft and pistons. The 74" pistons had to be machined half-way up the piston dome down to half the distance between the step at the bottom of the dome and the top ring land. In other words, the step on the piston was below the fire ring on the cylinder. I had to cc the pistons in each bore to match the volumes, dremel the piston valve reliefs for clearance and mock up the motor to check skirt clearance. Those Wiseco pistons did not need skirt machining and, after matching piston weights, balanced everything as outlined by S&S, trued and assembled the whole mess. BTY, my math showed both cylinders to be ~10.75:1 It runs very well to this day and makes a boatload of power. I have dual plug heads and have retarded the timing about 5*. It will occasionally ping if under a load such as going uphill at low RPMs,(shitty gas) so downshifting and going easy on the throttle helps. I run a dyna S ignition and have installed heavy(er) advance spring(s) on the advance unit. Make sure the advance unit is sound and lubed. When I used to go to the airport for 101 LL fuel pinging was less pronounced or absent, but it became a hassle when the airport would require a gas can rather than just fill the tank when I showed up(MV sales tax reasons) Other mods were done, but you wanted to know about pistons; I still occasionally use the shovel, but the Twin Cam RK gets props for having saddlebags.
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