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Fitting hayabusa gen 2 crank to gen 1 engine
Relph - 25/3/15 at 10:05 AM

Hi, I know a few of you guys have done this.
I'm going to use the gen 2 crank with a spacer under the cylinder block.
My question is can you use the original big end and main bearings if they are in good condition or do you have to get them measured / resized ?
And is there anything else that has to be modified / changed ?
Thanks

Angel Acevedo - 25/3/15 at 02:01 PM

Not Motor specific but for any motor I would use NEW same size bearings provided low miles and no evident wear or markings.
That's what I'm doing on a 5.0 V8.
It will need honing the bores and new rings.
HTH
AA

Relph - 25/3/15 at 07:58 PM

Cheers Angel for your advise, but I've read somewhere (can't remember where) about when doing this on a hayabusa engine you need different size bearings.
I already have new pistons, piston rings and cylinder block.

Thanks.

cosmick - 25/3/15 at 10:16 PM

I have done exactly what you are intending to do. You will be using the original con rods by putting a 1mm spacer under the cylinder, however, you will need to fit new big end bearings as it is unlikely to have the same colour bearings as the old crank. Furthermore, it is good practice to fit new bearings when refreshing the engine. The same applies for the main bearings. Check out the letters stamped on the new crank. It will read something like ABBAA. These refer to the sizes of the crank mains. There will also be numbers stamped on the crank something like 2222. These are the big end sizes. Once you have these, you can check out the con rod numbers and the letters stamped on the crankcases to work out the sizes to order. If you do not have a Service Manual, I would advise getting one.
Hope this helps.

Relph - 26/3/15 at 09:06 PM

Cheers Cosmick, that's exactly what I was looking for.

Where you pleased with the results ?

Thanks.

Angel Acevedo - 27/3/15 at 05:24 PM

quote:
Originally posted by Relph
Cheers Angel for your advise, but I've read somewhere (can't remember where) about when doing this on a hayabusa engine you need different size bearings.
I already have new pistons, piston rings and cylinder block.

Thanks.


When I read your post I understood the question as follows:
Either use the same size or resize.
Using same size implies no machining or grinding crankshaft.
Then for this option you can either use the same bearings. Provided you kept track of position and orientation... Very difficult for me and harder as number of Cylinders go up. Or, install new bearings of the same size. Which was my suggestion.
Grinding the crankshaft would obviously need new main bearings to suit.
I know next to nothing on bikes and Cosmick reply point exactly at that and leaves me thinking bike mechanics must be something like a Black Art...
I'm glad you found what you were looking for.
AA

cosmick - 29/3/15 at 10:48 PM

quote:
Originally posted by Relph
Cheers Cosmick, that's exactly what I was looking for.

Where you pleased with the results ?

Thanks.


I have made several modifications to the car since owning it and have increased the output by 15 horsepower. The crank extra stroke has also increased the torque by 6 ft/lbs so yes I am pleased with the results. I changed the air filter to a modified Hayabusa air box and force fed it at the same time. So I can't be sure as to how much is due to the crank change. Air box noise is now minimal. Driveability is greatly improved. Engine pulls sweetly from 2000 rpm in 6th gear.

BaileyPerformance - 30/3/15 at 10:42 AM

That would seem alot of effort for little gain?

We did back to back testing on the rolling road (in the same car) between a 1999 and a 2008 engine

We binned the factory throttle bodies and ECU and used Jenveys and Megasquit.

Nothing to choose between the two engines apart from a small amount of torque, the biggest single gain is the aftermarket engine management and Jenveys, we increased the late engine torque from 100lb/ft to 140lb/ft.
The engine would take full throttle from idle in top gear and pull cleanly to 13500RPM

If your still running factory engine management then i suggest that the first thing to look at, not the actual engine.

www.baileyperformance.co.uk
www.facebook.com/baileyperformance

Ciavatta - 8/4/15 at 10:29 AM

Did the same a while ago on mine: Gen2 crank into Gen1 block with Gen1 pistons/rods. I've used 1mm spacer and put brand new main bearings too. IIRC the bearings are different between Gen1/Gen2, the new ones have a slotted hole to match with the "channel" in the new crankshaft.

Remember to check the valve timing too, 'cause with the raised deck you can possibly have different numbers there.


Edit: I was right




[Edited on 8/4/15 by Ciavatta]