Author Topic: 175/200 Crankshaft Project  (Read 2092 times)

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Offline skiri251

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Re: 175/200 Crankshaft Project
« Reply #40 on: April 08, 2017, 12:06:32 PM »

Yes. Then off to Sears Point he following week. I'll be in either a garage on the front row or the one by itself when you first enter the track. #108 yellow and red paint. Still got a little ways to go. Gotta put the motor and the rest together!


p.s. See you there

Hope I can make it.

Offline bert Lilley

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Re: 175/200 Crankshaft Project
« Reply #41 on: April 19, 2017, 05:02:32 PM »
Hi guys , just reading your posts regarding the 175/200 center pin breakage and have a question
What material are you upgrading to when you replace the stock cente pin ?

I do undestand and support what karl indicates regarding the hormonics above 10,000rpm. Yes a 4 bearing crank would elevate a lot of the issues, i also think a professional balancing done would truly help as well.
A good friend of mine purchased a factory TD3 crank from Japan he took his pistons/rings  new crank etc  iand had tested for balance and it was realy out of balance. He was not impressed.

Bert Lilley

Offline OldSwartout

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Re: 175/200 Crankshaft Project
« Reply #42 on: April 19, 2017, 07:49:26 PM »
i also think a professional balancing done would truly help as well.
Bert Lilley

I got a quote about 10 years ago from a reputable balancing business here in Indy, it was going to be about $200 for a balance job on my 175 crank.  It had to be assembled without rods, they substituted balance weights for  the recommended percentage weight of rod, bearings, piston & rings and balanced the crank, then the crank ends had to be disassembled and the rods and lower rod bearings installed. Unfortunately, I never got around to doing it. It probably would have been a smart thing to do.
Karl Swartout
Mooresville, IN
BS175 Roadracer

Offline bsracer

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Re: 175/200 Crankshaft Project
« Reply #43 on: April 20, 2017, 10:43:08 AM »
I'm using an industrial dowel pin from Grainger that is 80 x 20mm. I originally bought them just to use for mock up and the machinist i use said they were pretty hard so why not give it a try. He shortened them and added centers. The original BS bearings fit well. The only problem I think I have so far is the way the holes were bored in the webs, not as accurate as it should be. One crank went together ok. The pin fit was a bit soft on the press gauge in my opinion. I'll see how it goes this weekend. Fired the bike up last night with that crank. The second crank had material move when the pin was installed and would not true to anything respectable.

I agree that balancing would be nice. Maybe in the future. We'll see how this one behaves this weekend. Ideally the new pin holes should be done with a Jig Bore machine. Still can't find a place that has one that isn't some big Gov contractor.


p.s. I think I will try just a new center pin to 20mm on the next one and have connecting rod pins stepped to minimize variable on the alignment of so many holes. 



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