Katana 750sz gearbox problem - help please!

[BigLT]

After finally getting my katana on the road it was riding, handling and running beautifully, until I couldn't change gear. I was within a mile of my house so nursed it home in first.

The clutch disengages with the lever as usual, so I can wheel it around, but I can't change it out of gear.

I'm hoping that someone will point out something really stupid that I might have done, or that I should check. I had the engine out during the build, but didn't go into the gearbox.

Any suggestions would be very gratefully received....I'm not sure I can face stripping it all down.

thanks in advance.

Liam

ps gsx750sz engine with about 10000miles. Wiseco 816 kit. standard carbs jetted. Anything else you need to know?
pps - this is under resin corse kat in projects. Before anyone asks, I was about to start prepping the bodywork on the day the gearbox 'went'.

[denisd]

Is the gear lever moving? Can you change gear with the engine turned off? 

[BigLT]

Thanks for your reply,

No, I can't change gear with the engine off. The gear shaft won't rotate either way when I use the lever.

[denisd]

Oops I think you might have to do some surgery 

[BigLT]

I think you're right...I was just hoping for a miracle! I could do with some luck at the mo.

[denisd]

Sorry Liam, I don't do miracles but fingers crossed lad, keep us posted please. 

[BigLT]

will do, and thanks anyway

[Captain Chaos]

might be enough to take the clutch out. Gearshift mechanism is visible then.

[Swiss Toni]

Is the circlip and washer still fitted on the gearchange shaft? If not, the quadrant could have slipped out of mesh and picked up again elsewhere! As CC says, whip the clutch out first and have a look behind it. Might save a lot of bother. 

[johnr]

take the sprocket cover off and see if it frees up, if the shaft is slightly bent, then putting the sprocket cover on will bind the shaft and stop it moving, as will the circlip and washer on the shaft where it goes through the cases. if it comes to it, you can take the clutch cover off and the baskert out and access the other end of the shifter mechanism.

[Dezza]

In my experience the same symptoms can be caused by something simple such as a broken return spring that may be accessible after the clutch has been removed. I hope you are lucky and it's not going to involve a case split.

[denisd]

9 minutes ago, johnr said:

take the sprocket cover off and see if it frees up, if the shaft is slightly bent, then putting the sprocket cover on will bind the shaft and stop it moving, as will the circlip and washer on the shaft where it goes through the cases. if it comes to it, you can take the clutch cover off and the baskert out and access the other end of the shifter mechanism.

He says it moves with the clutch lever pulled so that means the sprocket is moving freely 

[TonyGee]

15 minutes ago, denisd said:

He says it moves with the clutch lever pulled so that means the sprocket is moving freely 

he means the gear lever shaft not the sprocket shaft 

[denisd]

3 minutes ago, TonyGee said:

he means the gear lever shaft not the sprocket shaft 

Ah apologies 

[BigLT]

Thanks everyone. Lots of good ideas of where to start. Sadly it does feel like it might be internal, but I'll definitely try all this first.

...and apologies if my terms are confusing. What very little I know was self taught, and most parts are 'thingies' or 'doodads'.

[Dorkburger]

12 hours ago, Swiss Toni said:

Is the circlip and washer still fitted on the gearchange shaft? If not, the quadrant could have slipped out of mesh and picked up again elsewhere! As CC says, whip the clutch out first and have a look behind it. Might save a lot of bother. 

I had exactly this problem,  but mine was self generated...

 

[BigLT]

Right, errr, embarrassing admission:

Went through everything and finally noticed that the gear selector rod had 'unscrewed' itself so that the joint butted up against the bottom of the footrest when I tried to change down. I obviously hadn't tightened it properly when I was setting it. 

Tightened it up, adjusted the clutch cable and it now changes fine. I rode it to Loomies and back tonight.

Thanks again for all the advice and apologies for taking up your time. At least I know I have double checked everything now.

yours embarrassed...

[Swiss Toni]

Every day’s a school day!

[denisd]

Well at least you got sorted, embarrassment is cheap 

[TonyGee]

easy fix, happy days 

[jensvonbustenskjold]

I'll take that embarrassment any day.  Go ride your bike!

[stockcar]

from memory one end would usually have a 'locking' nut for this exact reason??

[BigLT]

Yep, there are in fact 2 locking nuts - neither of which I retightened properly after adjusting it!

[stockcar]

ooops...........

[KATANAMANGLER]

I read the through this and was about to reply to check the gear selector linkage for a foul and I noticed you found it.

Don't ask me how I know. 

Amusing to see how many people had you stripping your gearbox when no-one had asked whether the gear selector shaft would allow a gear change when directly operated without the linkage.