83 yamaha maxim xj750 - wont shift past 2nd gear

It's been sitting for nearly a year now. I finally bought some mirrors
and a petcock rebuilt kit. Charged the battery, and cranked it about
1-2 mins before it popped over and started humming like the old days.

I took it for a spin, but it was hard to bring out of first and into
2nd. After 2nd, it just won't go any further though. I can get it in
and out of 2nd fine now, but no amount of force can get it to go into
higher gears. The clutch seems fine, and shouldn't matter when trying
to shift into 3rd when the bike is turned off anyhow. Any
recommendations as to what could be going on here, and how I can easily
fix this?

I just bought the wife a new mustang, and the kid a boat for the
summer.. so my "fun funds" are dried up.. was really hoping that I
could get this working without taking it to the shop :/

TIA guys/gals

 

Go to www.partsfish.com and register so you can look at the parts
fiches for your transmission and the shifter mechanism...

I suppose the transmission shifted normally before you stored the
machine.
Maybe the sliding gears somehow stuck on the transmission shafts.
Gummed up by thick oil?

When you work the shifter lever, a monkey business ratcheting device
grabs the end of a cylindrical shifter drum and rotates the drum. The
shifter drum has weird-looking groves in it and little pegs on one side
of each shifter fork (there should be three shifter forks) are moved by
the grooves in the drum. The other side of each shifter fork has two
fingers that fit in grooves on the sliding gears. The sliding gears
have wide blocks of metal called "dogs" and the male dogs on the
sliding gears slip into female slots in the gears that don't slide.
Simple, huh?

The main thing is that the shifter lever has to rotate the shifter
drum, the shifter forks have to shove the sliding gears sideways and
the female slots have to line up with the male dogs...

Forcing the shifter lever may bend the shifter forks. The non-sliding
gears are located by metal circlips. Sometimes these metal circlips get
loose and bent and the non-sliding gears are pushed sideways by the
shifter dogs and the gears don't mate. That happened on my Yamaha dirt
bike. I couldn't shift into 5th gear as the 5th freewheeling gear moved
sideways out of contact with 5th pinion gear...

The shifter drum is held in the correct position for each gear by a
spring loaded detent that fits into a cam on the end of the shifter
drum. The spring loaded detent would be underneath the engine and the
metal cap would look like a second oil drain plug. It's possible for
the detent mechanism to hang up...

Have you put the motorbike up on the centerstand and worked the rear
wheel back and forth as you worked the shift lever up and down. That
might break some gears loose or realign them so the tranny will shift
all the way up to top gear...

 

You're SUPER! How easy was that!? I already had it on the center
stand.. went out and rocked the rear wheel back and forth and pulled up
on the gearshift and it popped right into 3rd. It's sliding in and out
of all gears just fine now!

Thanks for the terrific advice!!

 

You're the man! Up on the center stand.. wiggle tire back and forth..
and it popped right into 3rd. Works smooth now.

Thanks for the advice!

 

These bikes have chain (both timing and primary) tensioners that are
made of a semi hard plastic material. Over time, this plastic
disintegrates, the pieces fall into the oil and get sloshed around.
Sometimes, they get jammed into places where they cause problems like
these.

The only proper fix is to open up the engine and replace the
tensioners and get all the remnants of the old ones out.

As you have found out, sometimes wiggling can make the pieces move to
a place where they cause less problems, but sooner or later, they are
going to jam something important or block an oil passage. You should
get your bike fixed before it is too late.

There is an XJ mailing list at
http://www.micapeak.com/lists/xj-owners. It's been a while since I was
subscribed, but they were a bunch of very knowledgable and helpful
people. Might be worth a visit.