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Hayabusa gear change
JeffJeffers - 22/7/14 at 11:13 PM

Done a few miles now in my Hayabusa powered MK Indy.
The engine came out of a 2009 Hayabusa.
Sometimes When changing from 1st to 2nd and 3rd to 4th I get stuck between gears and end up with nothing. I then have to crunch the gearbox into gear again. Is this normal or does it sound like a part of the gearbox is worn out?

yahshuatwo - 23/7/14 at 03:09 AM

Sounds like worn dogs. This is the problem Im currently having with my gen 1 hayabusa ( tranny in 2nd/6th gears)
Suzuki was supposed to undercut the gears on year models 2005 > so they wouldn't slip out . Furthermore, your shift fork and rods are more likely bent. This makes it impossible to change gears.
Sounds like a tranny overhaul is required.

* split tranny case and send tranny to a shop to have the gears undercut
* replace oem shift fork
* replace oem shift rods with heavy duty aftermarket ones.

Research hayabusa undercutting on youtube

Cheers

Ryan

kj - 23/7/14 at 06:06 AM

What's the gear change mech cable or rods, might need adjustments as I had similar problem when first set mine up.

teegray19 - 23/7/14 at 06:34 AM

Sounds like a clutch problem to me, if the linkage is ok.. I would look to see if the bolts haven't come out of the slave cylinder.

I thought the box was gone on mine until I noticed I only had 1 bolt of three holding the slave on. It was rocking away from the block rather than actuating the rod.

Give it a quick bleed too! Nakered seals can do the same thing.

Might be wrong! Worth a look.

GreigM - 23/7/14 at 09:58 AM

quote:
Originally posted by teegray19
Sounds like a clutch problem to me, if the linkage is ok.. I would look to see if the bolts haven't come out of the slave cylinder.

I thought the box was gone on mine until I noticed I only had 1 bolt of three holding the slave on. It was rocking away from the block rather than actuating the rod.

Give it a quick bleed too! Nakered seals can do the same thing.

Might be wrong! Worth a look.

I agree with this - clutch is a possible....boxes are tougher than most people think. Also make sure your linkage is giving a full throw of the shift lever(very important!) and don't "snatch" the shift, a good firm push/pull is needed to make sure everything locates properly.

yahshuatwo - 23/7/14 at 12:56 PM

I would try the clutch stuff first cause its cheaper. But it sounds like what I posted first. I changed my clutch and the problem still remains

kj - 23/7/14 at 01:18 PM

Are you using the electronic shifter in you archive?

yahshuatwo - 23/7/14 at 01:32 PM

No. Manual /mechanical. No hydraulic clutch neither

MikeRJ - 23/7/14 at 03:51 PM

quote:
Originally posted by teegray19
Sounds like a clutch problem to me, if the linkage is ok.. I would look to see if the bolts haven't come out of the slave cylinder.


Unlikely a clutch problem since you don't even need to use the clutch when changing up on a bike engine, provided you lift off as you change.

Also unlikely to be a problem with the gear dogs - this would cause the box to jump out of gear rather than not go in.

Much likely is a problem with the gear linkage, e.g. insufficient throw due to design or due to free play/bending in the linkage, or the linkage binding so it doesn't cleanly return to the middle.

kj - 23/7/14 at 04:06 PM

I had some slack in my linkage on the rod ends lying under the car and turning the prop and moving the selector rod it was no problem but out on the road was when it showed up.

I spent more time under the car with my son changing through the box while i moved the prop, took it back out and the changes were a lot more slick and smooth.

Make sure that the movement from the rod to the gear change arm is as direct as possible.

jwhatley - 24/7/14 at 11:18 AM

Have you got the right leverage length on your shift selector? The gearshift does need quite a bit of leverage.

Any grinding noises in any gear? Its possible a circlip could have failed in the box if it is making a noise, making engagement a problem. I have had this before.

Doubt its clutch related as you should be able to shift through the gearbox on a busa without the clutch at all.

The selector forks for those gears are on different shift rods in the gearbox. It could be possible that you've bent the selector forks or damaged the dowel that goes in to the shift drum, which are all the same as the GEN1 engine but your going to have munched the gears together at some point to have done that.

Chet - 26/7/14 at 07:24 PM

It's been my experience that Hayabusa engines are pretty tough but respond best when they have ample supplies of good clean oil.

You might want to look at the simple solutions and work from there.

1. Proper oil level
2. Proper oil type.
3. Shift Linkage adjusted to provide proper throw.
4. Slave cylinder functioning properly.

Bent shift forks do occur but generally not without some very aggressive use.

Chet

Chet - 26/7/14 at 07:38 PM

FYI
-It's also important to know that there are numerous aftermarket ways to have trans gears undercut.

An undercut done in a drag bike style will result in a trans that is difficult to downshift in a car.

I'd suggest you make sure that the person actually doing the undercut knows that it is for a road or track car specifically NOT for a drag bike. The cost is generally higher for this "road race" style because of the extra cuts required.

Chet