Lost 1st gear

[jonyappleseeds]

Well.. I lost my first gear, the bike jumps rapidly in and out of gear. I recently rebuilt the tranny for this exact reason but I had it running fine all winter.

I started after I hastily dropped my 81 xs650 into 1st gear at a high rpm on warm up, I seemed to immediately have destroyed a component in the drive train. Recently I had replaced the shift forks, 1st gear and its worn dogs so I am hoping i don't have to crack the lower end open again.

Although I bought OEM parts maybe these old parts just are not that good? also maybe my clutch drags to much for there to be that much force on the drive-train when shifting into first. Or maybe I'm an idiot for rushing in the first place.

I just drained the oil (no sign of metal chunks) and have the right side cover off, The shift shaft springs are all intact. I'm going to remove the clutch and have a look at the arm position.

Is there anything else I should be checking for to cover my bases before I crack the thing open

Also has anyone else had this much trouble with their transmissions? Granted I bought the bike with this problem but I thought I had it fixed. I will note tho that this problem seems different --Initially before the tranny re do the bike would hold onto 1st and hop out under throttle. Currently the bike rapidly lurches in and out of gear.

Any insight will be be greatly appreciated thanks.

 

[TwoManyXS1Bs]

Hey, jony. Yep, you'll likely need to crack it open.

There's the outside chance that there's a problem with the neutral detent plunger and spring.
You'd be real lucky if that's it.

First three items to check are the 1st wheelgear, the shift fork and its slider gear. The engagement dogs and slots are likely rounded, which would bend the shift fork.

It's possible that excessive shaft end-spacing was the root cause.

Go to this thread, then into my album, and download:
(4) bulletins covering transmission GearboxSpacing
(2) bulletins covering InspectShiftCams

Yamaha XS1, XS1B, XS2, TX650 Tech Bulletins, Service Data, Brochures

 

[jonyappleseeds]

Thanks for your quick response. And also for a wealth of good information. I am reading all of these bulletins.

But now that you mentioned the neutral detente I went and checked it ,and it was actually pretty loose. which explains why neutral has been shifty on me lately, but idk how it be cause for no 1st gear?

Also this just occurred to me I have a later model input and output shaft.. Found that out when i got the overdrive 5th gear. But i did replace the 1st gear wheel and the dogs because they were rounded could this have happened again?

 

[TwoManyXS1Bs]

We had a couple of folks here with shift problems, traced down to damaged detente parts. Just something else to check.

Happen again? That's why I was thinking about spacing and shiftdrum inspection.

Might look into clutch disengagement, banging into first isn't good.
Many of us break the clutch free during kickstart...

 

[jay760]

Normally the dogs on the gearbox that wear out, when you watch it go into first in the box the dogs don't locate by much, the edge of the dog starts wearing and the gear it locates into starts wearing as well, this is when it starts jump out.