Feels like my FJR is jumping a cog in 2nd gear

[rogdeb]

From your video and description it looks to be the same thing that happened to my '03 a few years ago.

The dealer showed me the worn and bent shift arm + worn dogs after the fix.

Been quite a while but I think it cost me about $2k

 

[Ditch]

From your video and description it looks to be the same thing that happened to my '03 a few years ago.
The dealer showed me the worn and bent shift arm + worn dogs after the fix.

Been quite a while but I think it cost me about $2k

And I take it the bike would stay in 2nd gear? About how many miles did you have on it?

 

[eflyguy]

The dog slip sound is not the same sound as actually shifting gears. It's not even the same as a false neutral, but it's closer to that. Technically, it is a very momentary false neutral...

Exactly.. just a moment of loss of power, almost like something killing the ignition for a fraction of a second..

 

[wfooshee]

If it jumps out of gear into a false neutral, you've got really worn shift forks. If it slips and catches like this does, you've got wear on the dogs, as well as shift fork wear.

Thing is, they exacerbate each other. Wear on the dogs cause the gear wheel to be pressed up against the shift fork because the mating surfaces are worn at an angle instead of flat like they were made, and wear on the shift fork reduces the amount of engagement on the dogs, which causes more wear on them, in a vicious never-ending circle.

I had the issue on 4th gear, but got lucky with free parts from a dead motor and a bit of my own labor.

My own non-educated theory about why this happens in second, and to a lesser extent in 4th, is that those are the shifts that change forks. First gear is on a fork by itself. Shifting to second puts the first gear system into its neutral position and moves another wheel, on another shift fork, to engage second. Shifting to third moves that same wheel the other direction. Shifting to fourth puts the 2nd/3rd mechanism into its neutral position and another shift fork moves another gear wheel to select 4th. Shifting to 5th moves that wheel the other direction.

 

[Ditch]

Makes sense to me, what a bummer. My bought 20-something used bike and finally got bit pretty bad. Lucky I may have found a buyer that doesn't mind fixing it so we'll see but either way that sucks.

Can't thank you guys enough

 

[rogdeb]

From your video and description it looks to be the same thing that happened to my '03 a few years ago.
The dealer showed me the worn and bent shift arm + worn dogs after the fix.

Been quite a while but I think it cost me about $2k

And I take it the bike would stay in 2nd gear? About how many miles did you have on it?

Yes, the bike would stay in 2nd gear. The missing/slipping didn't happen if I shifted at lower speeds also.

IIRC (?) I had about 55 - 60k on it at the time. Maybe more ?

I don't have the receipts any longer as I gave them to the buyer a couple of years ago.

 

[Ditch]

So I took a deposit on it today, can I rest easy knowing this would have gotten worse over time?

 

[RossKean]

Yes, second gear would have gotten worse over time. Possibly to the point of having to skip second entirely (FJR doesn't mind going from first to third). On the other hand, spending a couple of weekends of quality wrench time and a modest amount of money for parts would have netted you a great low miles daily rider. Good thing you sold it - I was sorely tempted...

 

[wfooshee]

If interested, I added my gearbox teardown thread to my signature, so go have a look at what's involved. My issue started when the cam broke off of the shift drum, then I found gear issues while I had it apart and swapped in both transmission shafts from a donor bike. The thread starts getting interesting on page 6, and page 7 has the actual teardown pictures, and since I haven't used Photobucket in years and years, my pictures still work!

 

[OldernYZer]

"How could there not be a fix?"

I didn't say that. What I said was that good shifting habits can prevent it in the first place. There's a fix, but it's a matter of replacing the worn parts, not just adjusting your technique.

To understand what happens, you have to understand how your transmission works:

Each of the 5 (or 6) gear speeds consists of a pair of gears, one on the input, or main shaft, and one on the output shaft. All of the teeth on each of these pairs stay meshed at all times, and in each pair, one is locked to one shaft or other by splines, while the other spins freely on the other shaft.

To engage any gear, which is to say, to lock the free spinning member of any gear to its shaft so it can drive the rear wheel, the splined gear sitting next to the free gear moves over to it and locks the free gear to its side by means of lugs on the gear's side that engage with a matching set of lugs or slots in the side of the free gear. The power then flows from the driving shaft to the driving gear by its splines, to the driven gear, to the splined gear on the driven shaft through the locking lugs, and to the driven shaft.

A manual trans in a car works on the same principal, but when the locking lugs there get worn badly, the gears get forced apart from each other and move the shift fork and linkage so that the car comes completely out of gear into neutral. But in almost all motorcycles, the fork is moved by a grooved cam instead of a linkage, so the gear cannot move the fork when this happens.

Instead, when the force of the gears pushes hard enough to cause the locking gear to "climb over" the lugs, it has to flex the fork far enough to allow it. For that instant, the trans is effectively in neutral. As the gears rotate over one another, the lugs realign, and the spring load of the fork forces them back into engagement, resulting in an obvious jerking in the driveline. The force builds again, separates the gears again, and the cycle repeats.

All of this wears and eventually permanently bends the fork, which makes the condition even worse.