Author Topic: Custom Motorcycle Cranks  (Read 6715 times)

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Offline Anvil*

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Custom Motorcycle Cranks
« on: July 24, 2011, 02:00:47 AM »
Seeing this in a build discussion:

Chris, I suppose you don't want to hear about the hassle I had in getting a billet crank made (for my ZX12N Kawasaki).  Because of the specs we set forth, nobody in this country wanted to make it - so we found Farndon, in the UK.  They quoted 5-7 weeks, as I remember, with cash in advance, thank you very much.  I sent the check (which I had made sure would work well overseas) and started waiting.  Sure enough, their 5 - 7 weeks was almost, but not quite, correct. 

It took sixteen (16!) months for the crank to arrive.  *snip*

I do have a delay in funding currently but I had intended to have 4 billet cranks made for a small twin (plain bearing) with all required dimensions, tolerances, and finish provided. Marine Crankshaft Inc seems the natural choice, but I would like to hear others experiences (16 months on a 7 week build would have me in Farndon expressing my disappointment). I'm rather curious too why no one would touch the job in the US.

So, I'm curious and I know this group has saved a tremendous amount of time through it's collective experience.  8-)

Offline Beairsto Racing

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Re: Custom Motorcycle Cranks
« Reply #1 on: July 24, 2011, 02:55:45 AM »
Several years ago I had a Hayabusa +5mm weld up stroker done at Falicon...great service and communication. They also repaired a rod journal a couple of years later on the same crank after I threw a rod due to an oiling issue not their work. Again, great service.

I bought a billet +10mm stroker for the Busa from APE. I've bought alot of parts from them over the years for various street & race bikes, my experience with them for parts and service has always been great.

I had Marine de-stroke a Honda 600RR crank -7.25mm for a 500 turbo project. The work was completed on time, as promised. Marine did take on this project when their competitors wouldn't, so that makes them winners in my book. We recently sent them a Busa crank to get de-stroked for another project.

I suppose when a company is not willing to do a job, it is because the possibility of failure might reflect on them poorly, you have to respect where they draw the line with modifications that they are comfortable with.

Unfortunately Slim had some bad luck with the lead time overseas. I would not hesistate to use Falicon or APE for conventional crank work. I think when you need a crank shop willing to "think outside of the box", Marine is my choice.
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Offline Milwaukee Midget

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Re: Custom Motorcycle Cranks
« Reply #2 on: July 24, 2011, 03:24:26 AM »
Anvil*, I guess I'd ask first if it has to be billet.  In my case it did, but if your specs are such that a grinder can start with an uncut forging, you're likely to be ahead of the game.

If I had only needed to destroke my engine ~ 1/2 inch, I'd have been able to get it cut locally with a forging that was in stock with a supplier in Great Britain.

Just a thought . . .
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Well, I guess we're making a LOT of progress . . .  :roll:

Offline RichFox

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Re: Custom Motorcycle Cranks
« Reply #3 on: July 24, 2011, 06:12:31 AM »
I say again, If Crower can make billet destroker '26 Dodge Bros cranks. And Billet stroker '48 Cad cranks for about the same money your talking about. And start and finish on time. Why not give them a shot? They worked for me on GMC, Plymouth 4 rods and the Dodge crank as well as doing the Flat Cad crank and rods. I was very happy with the results. Ask Buddy and I bet he likes the Cad parts. USA-USA and all that. I did see a billet crank for a early ('13?) Buick, Great American Race car. Must have started with a 1200 pound bar. I was told it was a Valasco. Nice piece. Did any of you try Crower?
« Last Edit: July 24, 2011, 09:49:04 AM by RichFox »

Offline WOODY@DDLLC

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Re: Custom Motorcycle Cranks
« Reply #4 on: July 24, 2011, 08:57:53 AM »
These guys are in northwest Ohio - been there since 1926! I have not used them for years but they repaired many British-twin cranks for me when I was turning wrenches. [They specialize in babbitt bearings, too!] Don't know that they would do a billet crank but maybe they can steer you to someone! http://www.hartsmachineservice.com/home.html 419-399-4777
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Offline maguromic

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Re: Custom Motorcycle Cranks
« Reply #5 on: July 24, 2011, 10:57:06 AM »
babbitt bearings?  You're too young.  8-) Tony
« Last Edit: July 24, 2011, 11:02:20 AM by maguromic »
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Offline 38flattie

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Re: Custom Motorcycle Cranks
« Reply #6 on: July 24, 2011, 01:51:50 PM »
I agree with Rich- use Crower!

Crower told us 4-5 months, gave us a price, and gave us exactly what we asked for. They even sent Cad files, that we could use with our CAD models, to check theoretical fit.

Crower helped design new rods, that would except new SBC bearings, and still fit down the chambers. Crower was half the price of SCAT( don't like SCAT cranks anyway), and great to work with!

Crower is the way to go!
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Offline Anvil*

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Re: Custom Motorcycle Cranks
« Reply #7 on: July 25, 2011, 02:45:39 AM »
Thanks for the comments!

I'll start with Marine Crankshafts but also see if Crower would bid a small motorcycle crank and ask Harts machine service.

There's no off the shelf forging I could start with, it is posible to de-stroke a roller crank but it wouldn't take what I'm up to. It would work for the mule motor, but the thought is to work up to blown-fuel and plain bearings just handle the abuse better.  8-)