Yoshimura R&D Superbike

mtbspeedfreak wrote: No doubt...

I'm looking into a Falicon crank and rods - haven't initiated any conversations just yet though. My plans are to get the frame, suspension, and brakes sorted out before working on the engine. The engine will be the largest money vacuum of my life thus far, so that's better off waiting until I have a clearer idea.

Money Vacumn is right !!
Falicon used to do top notch work. Havent dealt with them since Tom sold out. I do love the workmanship and the performance on my Falicon Superlite crank. Spins like No Other :evil: :evil: :evil:

wireman wrote:

mtbspeedfreak wrote:

wireman wrote: Id just stuff an 1197 kit in there,I wont tell anybody! :woohoo:

Oh believe me, I thought about going that route. My displacement is set at 1015 cc's, so that can't change unfortunately. If you can't increase displacement, you have to increase your RPMs. I'm going to see what kind of sky-high RPM I can squeeze of of it. I don't think 11/12k is unattainable; with the proper modifications of course: increased oil capacity, windage tray, modified oil pump, Amsoil, oil cooler with thermostat, etc.

Anyone have any thoughts on this?

in order to make it breath at super high rpms is going to require one hell of a cylinder head"Hello Larry Cav".
The biggest problem with running these 900/1000 based motors is the same thing that makes them so tough under normal use!
Its the roller bearings in the crankshaft,once you start bouncing off 10,000 rpm range the bearings basically want to leave their happy little orbit and get thrown up against the outer bearing race and just quit rolling.
And if their not rolling their basically sliding/being drug along for the ride which is really tough on them like towing a car with emergency brake on. :sick:
On drag bikes that are doing this for a few seconds at a time it could take a long time to kill it,a bike running around a track in a circle with throttle pinned would kill it a lot sooner.
also do you think those old cast yosh pistons will take that kind of abuse?Id atleast have them dye checked for stress cracks even if theyre brand new.

Very good advice, the Yosh pistons were "pressure-cast" as opposed to simply cast. Obviously this method isn't as strong as forging, but I'll definitely look into getting them dye checked. I suppose aluminum can't be magnafluxed... :side:

Street Fighter LTD wrote:

mtbspeedfreak wrote: No doubt...

I'm looking into a Falicon crank and rods - haven't initiated any conversations just yet though. My plans are to get the frame, suspension, and brakes sorted out before working on the engine. The engine will be the largest money vacuum of my life thus far, so that's better off waiting until I have a clearer idea.

Money Vacumn is right !!
Falicon used to do top notch work. Havent dealt with them since Tom sold out. I do love the workmanship and the performance on my Falicon Superlite crank. Spins like No Other :evil: :evil: :evil:

Yep, I'm looking at the Ultra-lite Supercrank paired to the 1 piece Knife con-rods.

Another concern about rpm beyond design redline is valve float, which may have serious consequences if a valve head start hitting stuff it isn't supposed to.

Would consider heavy duty valve springs.

Good Fortune!

And Titanium Retainers too

high rpm = valve float = stiff spring which could cause too much valve seat pressure. top end will wear out fast.

Will Wiseco, MTC, or JE forge custom pistons? I'm wondering if I could get a modern, forged version of the slipper pistons created?

Are you limited to a certain piston design and bore size by the class you want to run in?
The main advantage I can see of the cast piston is the lighter weight,but at the same time they grow more than a forging so you have to allow more clearance for it .
Im just not sure how practical/safe it is spin one of these motors at that speed for long periods of time.
another problem is if youre building peak power at 12,000 plus rpms somehow where is the power going to come to life on this thing?
Can you imagine what its gonna be like coming into the corner at 10,000 rpms on one of these old monsters to keep the power up enough to come out of the corner at 12,000,im getting scared thinking about it! :woohoo: :woohoo: :woohoo: :woohoo: :woohoo:
And yes Falicon does build a hell of a crank :woohoo: :woohoo: :woohoo: :woohoo: :woohoo:

wireman wrote: Are you limited to a certain piston design and bore size by the class you want to run in?
The main advantage I can see of the cast piston is the lighter weight,but at the same time they grow more than a forging so you have to allow more clearance for it .
Im just not sure how practical/safe it is spin one of these motors at that speed for long periods of time.
another problem is if youre building peak power at 12,000 plus rpms somehow where is the power going to come to life on this thing?
Can you imagine what its gonna be like coming into the corner at 10,000 rpms on one of these old monsters to keep the power up enough to come out of the corner at 12,000,im getting scared thinking about it! :woohoo: :woohoo: :woohoo: :woohoo: :woohoo:
And yes Falicon does build a hell of a crank :woohoo: :woohoo: :woohoo: :woohoo: :woohoo:

No, I'm not limited at all, though I'd like to keep as "historically accurate" as possible - as long as my health and general wellbeing is not compromised. :blink:

So 12k rpm is a bit of an exaggeration, though I'm putting out feelers to see whether it's feasible or not. I agree, a corner at 10k rpm, would be interesting as the oil demands would be colossal!

Gearing is almost as important as RPM/power, it's "virtual horsepower," essentially. So a proper geared transmission would be absolutely necessary for an engine like this. I won't be keeping stock gearing, have no fear. :woohoo:

Patton wrote: Another concern about rpm beyond design redline is valve float, which may have serious consequences if a valve head start hitting stuff it isn't supposed to.

Would consider heavy duty valve springs.

Good Fortune!

Yes sir! Yoshimura makes a valvetrain hardware set (minus the actual valves)


I'm wondering if that set might work. Yoshimura R&D (America) is technically a separate company from Yoshimura Japan, so asking questions on these Z parts to Yosh R&D is a pain because they technically don't offer these parts stateside.

I contacted Yosh R&D in California via email this morning with the question:
"Can you get such parts from Yosh Japan to the US? Like the Yosh Z1/Z2 ST-L2 Camshaft for example?"

Here's the answer I just got via email this afternoon:
"Hi Bob,

Thank you for your interest in Yoshimura. Yes we can order you anything from Yoshimura Japan just let me know exactly what do you need (Yoshimura Japan website has part numbers) and I’ll be glad to contact Yoshimura Japan for pricing and availability.

Note: Yoshimura Japan orders require a 50% nonrefundable deposit and price is subject to change upon receiving, normally Yoshimura Japan orders take 3-4 weeks to get here.

Thank you.

Danny D.
Sales Representative
Yoshimura R & D of America, Inc
5420 Daniels St.
Chino, CA 91710"

Cool, thanks Bob! No doubt on getting parts, but I have some specific questions regarding parts. I'm worried that they will either not know, or worse, give me an incorrect "textbook" answer. I'll give them a shout to see if I can get in contact with someone at Yosh Japan.