With my bike going to be out of commission for a while I figured it would be a good time to do some mods to it. I have read and seen pics of broken crankshafts and read that they are caused by Cams that have larger lobes. Is this true? Is there a place I can look for these issues? I know this bike will not put out the power of an RC-51 or a new Duc but I would like to find out what it can withstand while being reliable. Ill end up buying a separate engine for this whole thing so I don't ruin the #'s matching unit. On my list of ideas is:
1) Knife-edge and balance the crank
2) Hi-comp pistons and H-Beam con rods
3) Balance rotating assembly
4) port / flow bench heads
5) velocity stacks (Step-father has a cnc machine)
6) experiment with an open airbox design. (foam dome)
7) individual exhaust (2-into-2) no x-over and equal length.
8) Cams... not sure the grind yet but also not sure if the crank will hold up, OR if Knife-edging the crank will make it more prone to cracking anyway.

Again just doing this to a spare engine because I think it will be interesting to see what this power plant is capable of. Ideas, questions, let me know. Ill probably crack into it within the next 2 months or so since my wife is due mid July. One question I will answer already for you wondering 'Why?', the answer is because its my money, my time, my bike and I want to so kindly F*** off (respectfully) lol. All other questions will be answered to the best of my abilities.

 

Ignore the broken crank and camshaft thing, not an issue.

If you're leaving the motor in the frame do the following:
Lightened flywheel, exhaust, filter, adjustable needle, tps reset, 15/43 sprockets, voltage regulator, stick coils. Then enjoy it.

If you are pulling the motor and disassembling it do the following:

Ignore the broken crank/cam thing...not an issue.
Balance and resize the stock rods, use ARP bolts. Order 2 JE 11.5:1 99mm pistons and check piston to valve clearance.
Order and install RC51 lifters and springs
Slot your cam sprockets and retard the intake cam 2 degrees. Or get a regrind from Webcams.
If you want new rods...Pauter Rods in CA will make them for 500$ a pair. A bit less for aluminum rods.
Install an RC51 transmission.

I can confirm that you will enjoy the ergos of a VTR over an RC all day long and...you can definitely hang with an RC if you do some mods.

That pretty much covers it

AV

 

as already said the bottom end on these things is nothing to worry about. they will take upto 135 rear wheel horsepower for as long as you keep putting petrol into it.

 

+1, and then some more for sure. Did I mention the arp rod bolts. The v shares rod bolts with a busa. Go figure.

AV

 

We've had someone here break a crank, why ignore that?

 

Have we? I must ha e missed that...thought it was a myth or one of those..."at 11000 rpm my crank broke..." Things. Kind of like a yeah but we'd pretty much expect that to happen, but not typically. I mean, my current rotating assembly is only trued for straight with balanced rods and it seems redline no issue. Whose crank broke? I'd love to read about it.

Av

 

Apparently the search function still works...

I sent the pics of the broken crank over to the engineer that helps me out and here is his very brief answer:


A very brief (no charge) answer.

 

You can ignore it , because there were very odd circumstances involved.... Also,, After extensive Google-Fu, I can't find any other reports of failure... Pick just about any other bike and search..... So it is just a random bizarre thing...


.Also...... "My Vacuum Cryogenics REMOVES THESE VOIDS AND STRESS CRACKS..." ????? No.... It doesn't.... May cause them to be less of an issue by hardening the metal around them, But no amount of any kind of tempering will fix a crack, or fill a void...

 

Cryo does not harden....it decreases the tendency to fatigue by changing the properties of the metal. The austenitic/martensitic conversion through use of cryo is a well documented and researched topic and has been for decades. I know personally from having conducted literally 100k or more ultrasonic shear wave tests, and other non destructive tests, on aluminum, steel, and other materials that this true. Hardly debatable like it was in the early days.

AV