Maney crank cases

Onder said:

Once you go down that road, where are you going to get to use this new found power?
What with today's legal enforcement and traffic conditions all I do is lope along with barely
a cracked throttle.
Don't build an unrideable street bike.

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My planned changes are not likely to greatly increase outright power, a few HP maybe, but not game changing. If I'm lucky, I'll be mid 60s RWHP. A highly tuned 750 would make more than that! The bigger gain will be in torque through the range I expect, so much nicer on the fun kinda roads that most of us prefer.

There are lots of folk with 920s, their feedback is that the set up makes a nice street bike motor. But its my first, so I'll have to wait and see.

However, as a reality check, even at mid 60s RWHP, it'll still be slow compared to most modern bikes. I just want it to be (even) more fun than it already is.

If it all goes tits up, I'll put my 850 barrels back on!

Because they have a lot thicker material than standard cases, ie thicker, you will have to relieve the engine plates around the engine area to make the Maney cases fit, no biggie.

Where are going to put the breather?

swooshdave said:

Where are going to put the breather?

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I will use the Comnoz / cNw reed valve breather on the back of the crank case as it is already machined for a Combat type breather there.

Fast Eddie said:

Awaiting its new home...

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Where does this one come from? Why not take a billet one?

Its from Steve Maney. I do not really know why he still uses a bolt up design to be honest! Probably because he started out making the flywheel interchangeable with stock cheeks I guess, and now he see's no reason to change?

Steve's cranks are very strong and well proven. They are also very light (relatively speaking)... a plus for light crank fans and a minus for heavy crank fans !

Crank weight is (in my opinion) as much about riding style and personal choice as anything else. I wanted to try a lighter crank in the Norton, as I have done so successfully in various other old Brit stuff. So I guess I am a light crank fan.

My bike is not a racer, its for fun, and I am looking forward to the characteristics of the light crank. I'm very happy with the choice, but other new options are out there for those who prefer heavier cranks, inc from Andover Norton and Nourish Engineering.

Fast Eddie said:

swooshdave said:

Where are going to put the breather?

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I will use the Comnoz / cNw reed valve breather on the back of the crank case as it is already machined for a Combat type breather there.

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Why not use the one he also makes that threads into the bottom of the crank case and replaces the big nut there. The one on the back will crowd the gearbox, when you're working on them and rotating the box to get it out, or so it seems from reading others posts here.

I didn't realise that CJ, can any users confirm this is the case?

Fast Eddie said:

I didn't realise that CJ, can any users confirm this is the case?

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I use Jim's sump plug breather on my Atlas. Works perfectly but it sticks out quite a bit.


Tim

Nigel, both my bikes have the bottom mounted crank case breathers.
Excellent except if you are prone to ride fast on gravel roads, mine took a bit of 'grit blasting" after a few rally rides took to the gravel.
No damage, just surface pitting
Regards Mike

Fast Eddie said:

NKN said:

Fast Eddie said:

I think the 920cc, cam, carbs, headwork, etc, should compensate adequately.

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OK, good luck :wink:

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Thank you. I'll need it !

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If your motor is going to be short stroke and 920cc, what bore size and cylinder spacing would you use to get up to that capacity. Would the pistons be offset on the rods ?

Isn't 920cc the largest capacity achievable using the 89mm stroke crank, before you run into problems with the bit between the cylinders ? How can you get to 920cc with a short stroke crank ?

I once thought about using a Yamaha XS2 type crank with a high tensile steel plate carrying a bearing inserted between the crankcase halves to carry the centre of the crank. Even if you do that you would have a problem with centering the combustion chambers and squish bands and getting the valve pockets in the right positions in the pistons.

acotrel said:

Isn't 920cc the largest capacity achievable using the 89mm stroke crank, before you run into problems with the bit between the cylinders ? How can you get to 920cc with a short stroke crank ?

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I don't think he ever said it was a short stroke crank, Alan, just the standard 89 mm stroke.

Ken

acotrel said:

I once thought about using a Yamaha XS2 type crank with a high tensile steel plate carrying a bearing inserted between the crankcase halves to carry the centre of the crank. Even if you do that you would have a problem with centering the combustion chambers and squish bands and getting the valve pockets in the right positions in the pistons.

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Not really that big a problem. The combustion chamber isn't centered to start with. For the 83 mm bore in the 1007 kits, Steve moved the cylinder bores outward 1 mm on each side. He relocated the cylinder head bolts to accommodate the extra width, and machined the counterbore to match with no problems. For the pistons, we just had JE move the centerline of the valve pockets inward a similar amount. If you wanted to spread the cases further apart, you might have problems, but it worked find in this case.

The conversions to a center main bearing that I've seen didn't involve making the cases any wider. They just machined the inside of the cases for a bolted in center bearing carrier. In one case a new plate was welded between the cases, but they were machined down before so that the width remained the same. Both were done some years ago, one by a Canadian racer, and the other by our own Jim Comstock. I think Herb Becker might have also done one, but I'm not so sure about that one. If you search the forum, I think you can still find some info on the one Jim did.

Ken

Not sure where the short stroke conversation came from? Certainly nowt to do with me.

I'm using stock 89mm.

The crank in the pick has 89 sampted on the top of it. Which I suspect is linked to the stroke size....