Kawi2strokes.com Forum

Any feedback on the 18mm wrist pins?

We found that the 16mm stock H2 wrist pins that we had as H2R pins were a problem at higher rpm's, they flexed, and caused the piston load bearing faces to flex front to back, distort in the bores, and fail the pistons. We had tried to do 18mm pistons, had some benefits, but too many other problems, mostly forged pistons. We did try cast pistons at the end of the 1973 season, but most of us got the ax before we could do much with them, and Randy Hall didn't seem to care, or, appear to have any workable knowledge on the subject.

I haven’t had any feedback. I think with the Wossner pistons they should be fine. I really don’t have enough experience to give any expert opinion.

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Crankshaft Testimonials viewtopic.php?f=25&t=7593

"Let's keep your crankshaft great!"

The drag racers have been using Yamaha MX 250 rods for decades, as they were 5mm longer for a better rod ratio. They also came with 18mm small ends, so it seems there is no problem. And setting many new records through the years.

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Twist the throttle, tilt the horizon, and have a great time. What triples are all about...........

I 've done more than a casual few H2 cranks with the Yamaha rods, great modification.

I just wondered about the stock dimension H2 rods with the bigger pins. The very few times the factory listened to us and did special test stuff, the pins, bearings, rods were great, but the modified factory forged pistons weren't, as they were simply bored pin boss 16mm ones. They flexed worse, because the smaller pin bosses distorted worse with the lack of adequate pin boss area and strength.

From what I heard, they had an alternate piston that used 18 mm pins.

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Twist the throttle, tilt the horizon, and have a great time. What triples are all about...........

I just checked. The 18mm pistons are on order. Fast by Gast may carry them.

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Crankshaft Testimonials viewtopic.php?f=25&t=7593

"Let's keep your crankshaft great!"

I just opened a beer to celebrate the new vintco crankshaft I have sitting on my bench!
Thank you Charlie.You made this quick and easy.
It will go with the new wossner pistons that I got from Jim at fast from the past.
Now I have to actually work on my own stuff just in case a racetrack is open in the near future

I would like to offer a winter special Starting today through the end of February 2021, I will include with a crankshaft rebuild a free vapor blasting of the crankshaft or a set of three disassembled carburetors. This includes ultrasonic cleaning as well. This is normally a $50 service. Thanks! Stay warm!

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Crankshaft Testimonials viewtopic.php?f=25&t=7593

"Let's keep your crankshaft great!"

Good deal Charlie. By the way, my H2 ran great all year, so thanks again for the rebuild and the support!

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If it surges, that's normal, upshift.

It was my pleasure Jim!

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Crankshaft Testimonials viewtopic.php?f=25&t=7593

"Let's keep your crankshaft great!"