Gearbox problem

[mo123]

Hi, I have a problem with the gearbox on my new to me 1987 FJ1200. It's only got 35k miles on it genuine. It jumps out of first gear at around 5000rpm or when accelerating hard. When it's in neutral and on the side stand it makes a really bad knock or rattle which seems to be coming from around the gearbox. If I have the bike upright it sounds fine and as soon as I tilt it over to the left it starts rattling and knocking. If I put it into any gear and hold the clutch it doesn't make the noise when I tilt it. It drives well apart from the problem in first and the engine sounds good.
A local garage said the problem lies with the selector forks or the first gear cog and it's rubbing off another cog when tilted over. They quoted me 300 on labour plus parts to fix it.
What do you guys think to that? Has anyone else had this problem?

[simi_ed]

Yes, I've been there. Yes, you have bent shift forks. Yes, it is expensive. Sorry.
If you're going to fix this, or have some else do it, you need to get an undercut transmission. Don't fool around with some gears, do the whole thing. Do all 3 shift forks too. Otherwise, you get to do it again.

Don't ask me how I know.

[yaman]

Yes, I've been there. Yes, you have bent shift forks. Yes, it is expensive. Sorry.
If you're going to fix this, or have some else do it, you need to get an undercut transmission. Don't fool around with some gears, do the whole thing. Do all 3 shift forks too. Otherwise, you get to do it again.

Don't ask me how I know.

words of wisdom right there

[mo123]

Thanks for the reply. So I'm looking at a complete gearbox replacement.. I don't have the funds to get an undercut transmission so I'm looking for a used gearbox from another bike. Will any year gearbox work in my bike or does it have to be a 1tx box? Does the engine have to be completely split for the job or just partially? I've seen a bottom end gasket set for sale.. 

[jscgdunn]

The transmission will interchange, but the shift forks are upgraded in later models.  Where are you located?

[jscgdunn]

The transmission will interchange, but the shift forks are upgraded in later models.  Where are you located?

Oh yeah...and the cases do need to be split

[mo123]

Thanks, I've picked up a second hand complete gearbox from another 1to including selector forks so that should sort it. I'm in Ireland.

[jscgdunn]

It probably would be worthwhile to put the later shift forks in as they are the weak point.

[copper]

Thanks for the reply. So I'm looking at a complete gearbox replacement.. I don't have the funds to get an undercut transmission so I'm looking for a used gearbox from another bike. Will any year gearbox work in my bike or does it have to be a 1tx box? Does the engine have to be completely split for the job or just partially? I've seen a bottom end gasket set for sale..  

Why spend a couple hundred extra bucks to do it right the first time..... when you can do it a second time?

As Ed has already told you do it right the first time or be prepared to waste your time and money to do it right the second time.

Do your self a favor and wait a couple weeks to save up the extra cash to do it properly.

[aviationfred]

The upgraded NEW shift forks are a small price to pay for many years of trouble free shifting.


Here are the shift forks to order.

Shift Fork - Left

Shift Fork - Center

Shift Fork - Right



Fred

[simi_ed]

Thanks, I've picked up a second hand complete gearbox from another 1to including selector forks so that should sort it. I'm in Ireland.

Wow!  Fundamentally bad choice!  
Are the dogs worn on this used trans?  If so, you just took your POS and installed somebody else's POS.  How about the bearings?  Same goes here.  Used shift forks?
I did something similar, got to do it over again.  I only fixed the rounded 2nd gear.  The first time I gave WOT in 1st gear, that fork failed, rounding the dogs & bending the 1st gear fork (OK, it was one of Randy's hot rod 1314cc motors ...) Motor back out, upside down.  Gut bottom end, split cases. Replace bent fork and entire gear set with undercut gears.  Reassemble & reinstall! Problem solved, even with (hotter) 1350 motor and WOT in 1st or 2nd gear. Don't be as stupid foolish as I was, you'll regret it!
It's your bike, it, your money & your time so you can make your own decisions ...  I have nothing more to say.  

[mo123]

Doing all that just isn't an option at the moment. Would I be better off trying to get shift forks from a later model? The one I got only had 30k on it and was working perfectly. Is it that common for them to go? Am I more than likely going to have the same problem later on? Should I see if I can cancel the order and pick up a later model gearbox and forks?

[simi_ed]

Doing all that just isn't an option at the moment. Would I be better off trying to get shift forks from a later model? The one I got only had 30k on it and was working perfectly. Is it that common for them to go? Am I more than likely going to have the same problem later on? Should I see if I can cancel the order and pick up a later model gearbox and forks?

IMHO you'd be better off sucking it up and riding 'as is' until you can do it right. If you can bail out of the order of the 1TX parts that'd be great.
Don't waste your time & money doing it half-assed. Any pre '92 parts are suspect, I believe. I'd also say any and all used shift forks are a poor bet.  Do it once, do it right!

[racerrad8]

You would be better served riding as is and saving the money to do it properly. I wouldn't suggest putting a used transmission in it at all. Was this motor flogged, missed shifts? Did the motor blow up and got something in the gears possibly damaging a tooth? Was the transmission screwed up and replaced and is now being sold as a "good" used transmission? Does the person selling this transmission even know what to look for on the pinions and wheels to tell if they are damaged or worn already?

Robert - RPM

[simi_ed]

Leopard?  Just wondering ...