1981 XJ650: Issues shifting down one gear

I've done some searching in the forums can't seem to find similar issue.

I can upshift but when downshift, it can only shift down ONE and the rest, the pedal doesn't seem to engage a gear unless i stomp on it or stop and reverse.

i was able to pull the ccover out and see the shift lever assembly. Everythign seems to shift... but can anyone shed light if this is a simple spring issue? I've uploaded pictures to let you see if you see any wear and tear.

Here's scenerio.

When shifting to [1]to [2]to [3] OK
Downshift: [3] to [2] OK, then stop reverse, shift to [1] (or i stomp it down during motion)

Similarly, when Shift up [1]to [2]to [3]to [4] OK
Downshift: [4] to [3] OK, then have to stop bike, reverse, shift to [2], then reverse, shift to [1] (or i can stomp these down during motion)


Similarly, when Shift up [1]to [2]to [3]to [4] to [5] OK
Downshift: [5] to [4] OK, then have to stop bike, reverse, shift to [3], then reverse, shift to [2], reverse and then shift to [1] (or i can stomp these down during motion)

 

See that hole in the inner case, just above the shift drum?

Get a bright flashlight and an inspection mirror, and have a peek through the hole. See if you see any spurious, stray "hunks" of black plastic bouncing around on/getting stuck in the shifter forks.

If you do, pluck them out as a temporary solution to the real problem-- a disintegrating primary chain guide.

 

Are you referring to the hole in picture, img_20121113_211042.jpg ?

i did a peek... but no plastic chunks. Maybe i need a dentist type mirror and stick it in there...

 

Yep. You can see it in 211627 also.

The "primary" (drives the alternator/starter jackshaft) chain guide disintegrating is a known issue with the shaft-driven XJs. If hunks of plastic then get caught in the shifter forks, it can jam things up. I't possible that by "stomping" you've forced pieces further in.

If you can't find anything, are you sure the clutch is adjusted correctly? A dragging clutch can make shifting difficult.

Another thought: are you doing this with the bike AT REST? You can't shift through the full gearbox without rotating the rear wheel; sequential gearboxes don't work that way. In order to run through all 5 gears, you'll need to have the bike on the stand and turn the rear wheel if it's not in motion. Or turn the output shaft if the motor is out of the bike.

 

i changed all the springs, dowels and also installed an ADDITIONAL collar. The collar was no present in 1981 Yamaha's. The test appears to be successful so far w/o actually starting the motorcycle. I'll update this forum in spring when i actually ride the bike.




HCP5143 OEM shifter lever shaft TORSION SPRING WITH COLLAR, for use on all 1980-81 XJ650 and XJ750 Seca models that use the collar underneath the spring. This is the set that is needed to update the weaker spring used on the 1981-82 engines.
$ 12.95

 

As an update to this post, i believe adding the additional collar fixed my shifting issue. My bike is able to downshift properly now. YAAAAYY!!!

It's part 8 in picture.

 

That's good. The spring and collar, the one bottom right of pic 211048 ? like in this schematic 3 and 4 where 3 is labelled ' stopper lever assembly '.
http://www.cmsnl.com/yamaha-xj750rh-sec ... ml#results Does the collar go over the round part of 3 thereby keeping the spring stabilized better.

 

One thing I missed in the original post.

The gearbox WON'T go through all the gears without at least rotating the rear wheel (or moving the bike) as you shift; it's the nature of sequential gearboxes.

 

Nah, see you did already cover it Fitz. :wink: Good point to remember all the same. I remember when I first learnt to ride, trying in vain to select 1st & thinking my gearbox was bust until I was told to roll the bike back a couple of inches & try again

 

No fer sure i was trying to downshift while the bike was still in motion. The shifter had too much slack and installing the collar (that was implemented after 1982 models) fixed the issue.

On an interesting side note, since fixing the gear shifting issue, my bike goes into NEUTRAL properly (as indicated by lights on dashboard), which helped my starter issues. Previously, my bike wasn't shifting properly so it didn't detect NEUTRAL properly so my bike starter wouldn't work.

The reason being is that there is a safety feature where it won't allow you to start it the bike is not in NEUTRAL gear.

 

If your safety circuits are fully functional you CAN start the bike in gear (as long as the side stand is up) with the clutch pulled in.

 

My apologies for bumping the thread, but this is exactly what happend to my bike.
A black plastic part approx. L 10x w10x H6 mm wa stuck in the drum hindering the forks to move kuggs into any gear.
Taken it out and the gear box is like new. But!

As you mention below, there is a real problem and that is the chain seat that the tiny small part loosened from.
I have tried to identify that the part is from the end of the chain guide and
Would you say that this needs replacement before I can use the bike or will the chain guide do the job as is?

I have started her up and there is no rattle from the chain area.

Thank you so much in advance for your input.

JR

 

JR; Once the chain guide starts breaking up, it will continue to do so.

You can go ahead and ride the bike but another chunk can break off the guide at any time and the problem re-occur.

Replacing the chain guide will involve removing the motor and splitting the cases, if you have a 650/750/900. You will need a service manual for this procedure, there are certain critical details that must be adhered to.

 

1981 xj650 maxim ... mine is having this sort of issue. It will not shift from first.. I checked the springs in the shift lever box and the collars , it's all fine. But the drum will not turn either direction.. originally before I took it apart to look at it.. the shift paw would move up and down. But no "click" to show that the gears are changing . it's stuck in first , will not change to any gear upward nor will it shift to into neutral .. I'm guessing it's something on the other side of the drum, because the selector arm assembly will not turn the drum either direction. What is causing this ?