Commando Crankshaft Porn

(Edited with additional details 1/3/11)

There have been a lot of interesting pictures of crankshafts on various posts here, so I thought I'd try to get as many of them as possiible in one post. I'm posting all the ones I have collected over the years, and hope others will add to them.

First, a factory Commando crank modified the way we used to do them back in the '70s. Custom steel flywheel, heavy metal, radiused output shaft, shot peened, and high strength 3/8" fasteners. This one is still running in a friend's 920 AHRMA twins class race bike. I ran it in my 750 Commando Production Racer with a 62% BF. The 920 is in a featherbed frame, and I added more heavy metal to he flywheel (not shown in this picture) for an 80% BF. That seems to work really well for this particular bike.



Next, a Dave Nourish 89 mm crankshaft with Crower titanium rods from Martin Adam's Commonwealth Norton racer, now owned by Fred Eiker and running at Bonneville as a landspeed bike. Martin's bike had a Caffrey Seeley replica frame and 872 cc engine. The crankshaft BF was a little over 80%.



Another Nourish crank, this one an 80.4 mm 750 short stroke with Carrillo steel rods, part of an engine build I'm doing now. I had this one made with the wider width to fit Mk3 850 cases. I raced it one in my PR for a while with the stock steel rods (till one broke) and a 62% BF. I replaced the rods with Carrillos with no other changes, which raised the BF to 71.6%. It still worked fine with the isolastics.



A Falicon 89 mm stroke crank built for Kenny Dreer, with larger diameter main bearings. It's on the shelf, along with the crankcase from Kenny with larger bearing bores, waitng for me to decide what to build with it.



An offset crankshaft by Chris Large. I don't know the status of this one.



An offset crank by Geoff Collins. Geoff makes these, along with other confiturations, to order.



And last, but not least, our own hobot's Geoff Collins crankshaft with custom steel flywheel by Ron Fraturelli. I'm in the process of modifying this crank, but at the moment, it weighs 21 lbs.



That's it for now.

Ken

(Edited 1/3/11 to add more details)

And one more, a 91 mm Nourish crank, without the large lightening holels in the short stroke Nourish crank I previously posted. It makes for a very heavy crank, but it worked well with 80.5 mm pistons on my race bike. That's grease, not rust on the crank, in case anyone was worried about it. This one is also waiting on the shelf for me to decide what to use it for. I used this in my Commando PR for AMA Pro-Twins racing until the cases broke at Daytona. The BF was 62%, which is what I preferred for engines I raced in isolastic frames.





Ken

And yet another, this one a Steve Maney crankshaft, with flywheel and halves machined by him on his CNC equipment. Available in a variety of strokes. I have several of them, but haven't taken any pictures yet, so this is the one from his websiste.



Ken

Boy too bad Norton don't have a sight glass in their cases! Could they?
Peels looks so old fashioned crude. Could you give a ballpark listing of what each crank might cost for some ID of bang for the bux? Guesstimates of which is stiffest most rpm tolerate? Total weight each across this scope would be lasting educational - if extra time to spend on others.

Minus the shipping and straightening and plating and drill lightening, most the exce$ Geoff returned to me, so Peel's ball parks at $1500. How many towels needed for tears and other juices spent on Commando life style?

Hi Ickren
Thanks a superb collection of cranks.
Some of the made up offset cranks are amazing. Not something I would even dream of trying!!! Stunning stuff.
Keep it coming
Chris

this one is from Jean Noel Gindrat, a french tuner who made most of his stuff himself..........

Great, I love porn. As long as it's dirty motorcycle parts.

Here is a 89mm crank from my old racebike.
It was the second crank built . The first one weighed 15 lbs and I could not get good track times from it. The one in the picture weighed 18 lbs. and was much better. If I put it back together again it will be 22 lbs or so. Balance factor was 65%


And a short stroke crank from the same bike.
It weighed 15 lbs and was balanced at 65%


And here is one for people who like large handgrips. Rev the engine and the handgrips would get about 2 inches in diameter. A few miles and your hands would crack and fall off.
It weighed 14 lbs and was balanced to rotating weight only.


And here is the 91 mm crank ready for the new engine I am building for my bike.
It weighs 24.5 lbs. 2 lbs more than a stock crank. It is balanced to 60%.




And last is a custom 4 piece crank
It weighs 19.5 lbs. and was well overbalanced which was likely part of the reason it broke.

Wow to all the hi end variety displayed, even Jim's applying newest fracture technology like they do rod big ends now. Costs extra I'm sure, custom always does.

Looking at those pics, I got excited. Had to slap my lap.

The last one pictured has VW and Audi markings?

After all the following these seem almost plebian:



As seen in another post. Falicon, Carillo, JE

I ziped it into the cases and measured .014 end play with no shims and no Yamabond; to think that 39 year old cases could mate with a crank that is less than 3 months old and work so well!!??

RS

quote:
Were you running a 3rd centre bearing in these engines?
Also did the have roller mains or plain bearings? Pretty impressive work

I had a set of original cases that I modified with a center main and plain bearings. The cranks were made from VW water cooled diesel cranks.
I have a third crank that was cylinders 2 and 3 from a Mercedes 6 cylinder but it is in a motor. Jim

Awesome stuff, amazing!

comnoz said:

And here is one for people who like large handgrips. Rev the engine and the handgrips would get about 2 inches in diameter. A few miles and your hands would crack and fall off.

And last is a custom 4 piece crank

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I would have thought a 180 crank would have been smoother :!: :!: Didn't the Yamaha XS650 have a 180 crank at some point (I think they went for a 360 crank only for the sound), the Honda 450 was a 180 twin too and what about the Laverda 750, that was a 180 twin wasn't it :?:

Is that Kenny's crank :?:

Jean

Jean, The 180 degree crank created a rocking couple. IE side to side movement. Mounting it in a frame with isolastics did not work. It made serious vibration. I know a guy in Canada who built a 180 motor after I tried mine. He put it in a solid frame. It also vibrated quite a bit. He took it to the racetrack and it broke the engine cases in it's first race. I also used a 6 cylinder crank to build a 270 degree motor. It was not much different than the 360 motor. It seemed to vibrate a little less at low speed and a little more over 5000 rpm. Jim

And yes that crank was modified by Kenny.

The 750 Laverda was 360° with the cam chain driven from the middle of the Crankshaft 4 balls bearings and rods running on roller races (very similar to a 2 strokes crank)
Yamaha 650 was 360° , all other Japanese twins including Honda CB 350 , CB 450, Yamaha 500 XS were 180° the latest with balancing shaft , as well as 500 Ducati parrallel Twin ( may be not a lot of this one went over the pond)

I raced this crank in my 850 monoshock. Sold it to Ken Canaga and then he raced it for awhile. Now its in my streetbike with the lightweight pistons/longer rods. All this after the original owner was finished with it. It has a lightened flywheel and radiused and polished PTO shaft. Weighs 20lbs. I used to rev it into valve float range when I raced. I've magnifluxed it and there are no cracks. But I always used lightweight pistons of one version or another.

Jim



Good to see the lightweight pistons and bushless rods in the post above by "RoadScholar" - should be a smooth running motor.

I was thinking it would be of interest if the posters could edit their posts giving the weights of the bare cranks at least but any other info like BF etc. also and whether they are designed for 750, 850 or ______.

Steve Maney crankshaft in pound cost units of course.

WEIGHT SAVING EXAMPLES
Standard Norton crankshaft--------------------22-24 pounds
One piece billet crankshaft-------------------------28 pounds
Maney lightweight crankshaft-----------------17-18 pounds
This incredible weight reduction dramatically improves acceleration, and reduces stress on the crankcases

Standard 89mm stroke crankshaft ... �1,150.00

Click to expand...