Pretty Sure I Broke a Shift Fork!

ColdBusa

Take this Jerry, you silly little rodent
Donating Member
Registered
I was out for a ride yesterday. Nothing crazy, and I had stopped and taken a left turn. While in first I increased the RPM's up to around 7K RPM then shifted to 2nd. As soon as I let out the clutch I hear "bang" and then an awefull grinding noise, which I thought was the motor, but then my back tire locked up on me. I immediately killed the motor with the kill switch and pulled over.

I stopped on the side of the road looking at the chain, etc to see if I could see anything. Nothing visual. So I put the bike in neutral and fired up the bike again. Sounds great with no problems. Shift into first. Seems to be okay so I start to roll very slowly. I hit around 3K RPM and the grinding/squeeling noise comes back. So I think crap I gotta get this home and limp it there. I shift to 2nd keeping it below 3k RPM. Everything's nice and quiet. Shift to 3rd, things are good. Shift to 4th, and by this time I'm doing around 90 kph. Then "bam" the back tire locks up again.

I pull over and try to shift it down to first, thinking screw it I'll get my trailer and get it home that way. However, it will shift down to neutral, but not first. I can shift up to 6th and down, but not to first.

Now here's the thing that makes me think it's the forks. When in Neutral and the bike running with the clutch pulled in, it is fine. As soon as I let the clutch out, the trans is engaged, so still in gear. When I shift to 2nd at stand still, with the clutch pulled in and try and push it forward, it will only go about 6" and then it's like the rear brake is applied and the bike stops dead. Same if I roll it back. It will do this in all gears that I can get into with the exception of neutral.

When in neutral and pushing the bike forward, I can hear binding/grinding that will come and go, and I will feel resistance when the grinding comes.

Like I said, the motor runs like a charm and when in neutral, I can run it and it sounds great and I can rev it up, but not in gear.

What are your thoughts?

Definitely gonna have to pull this bugger apart.

Oh yeah, the tranny is stock as well as the forks. What could cause this to happen? I won't know the mode of failure unitl this weekend or the next..:banghead:
 
Pull the clutch cover first, Ace's bike just had the clutch pressure plate bolts back out last week! \
 
Pull the clutch cover first, Ace's bike just had the clutch pressure plate bolts back out last week! \

Will do GixerHP. Then I'll pull the oil pan and see what goodies are in there..lol.

On that note, what brand would you guys recommend for new forks?

Gonna also get the trans upgraded when the damage is assessed and do a heavy duty output shaft...might as well make it beefy...

Thanks Dscahill. If it would have been on a corner it wouldn't have been pretty at all. I almost went off the highway as it was!
 
the output shaft on the gen 2's is pretty strong if i recall from reading these boards.
the tranny is also pretty stout
 
I dunno man, I've never encountered a bike with the symptoms you described. With bent shift forks the bike won't shift properly, or will fall out of gear.

Years ago on my first engine i didn't install the shims properly on the needle bearing support bearing ends of both trans shafts and it was noticeably hard to turn, and would eventually the trans would lock. I doubt that's your issue though.

Only other thing I can think of is you got some metal shavings or something jamming up your gears in the trans. I've only ever heard on a trans completely lock up on a moving bike once.

But if it does need shift forks, slap a set of gen 1 forks in there, they are stronger.
 
I was thinking that if I snapped a fork, it could have rolled forward on the output and binded with the input side. Just speculating at this point. Thanks for the post murdered..I'll let you guys know when I pull the pan to have a look.
 
U can see the trans from the bottom of the cases.Pull th pan ad have a good look.U can sneek the forks out if you just need a fork.And yes those transmissions are really tough for a stock setup.
 
That's good to know gsxrdan2. I'll pull it tomorrow and have a look. I have a wire cam as well that i'll feed in there to snoop around. That way I can really have a look.

Though I don't have a stock setup, as the motor is fully built with a turbo (low boost right now), except the trans. Plus I've put alot of passes on the bike from last year using an air shifter, so that might have been my issue and it was just it's time to fail...
 
Hey guys,

I have a bit of an update on this. I pulled the clutch cover to have a quick look. It looks like both forks on the output shaft are in tact. However, the one near the 1-2 shift mark looks like the nipple might be worn down, or out of the groove. I didn't toss my camera in there yet to verify (pretty late night here right now).

On top of that, I pulled the oil pan. Absolutely no metal filings to be found in the pan. I was expecting pieces or at the very least some sparkling in the oil, but nothing!

I had a look from the bottom, and having the shifter move, it looks like the shift drum is moving no problem from "neutral" (which is still in gear) to 6th gear. However, it doesn't look like the shift drum will move forward to 1st year.

I can't see the output shaft that great from the oil pan with the oil intake on, and the input shaft in place, but from what I can tell, I see no tooth loss, or wear from the bottom and from the clutch side.

Tomorrow I'm going to remove the sprocket cover, see if there's something in there, as well as the shift gear cover. Maybe I broke a tooth on the spline for the drum, but I do see slight movement when trying to get to first. Which still makes me think that the 1-2 fork isn't moving properly.

Thinking about how much the wheel will move, and the spacing of the dogs on the trans, it seems like it will rotate until the dogs touch. So I'm still thinking it is that one fork that is either out of the drum, or the nub has been worn off.

Still, it's good news as I don't think I'll have to flush the motor or anything like that. Still trying to figure out if I will have to drop the motor or not. Seems like there are some people that have changed the forks with the motor in the bike, and some that have to remove it. I'll keep ya posted on what I find tomorrow. Though I would like to take the trans out and build that mother up...lol
 
Am I right in thinking that the screen on the oil pickup would capture large pieces and that the filter would catch the smaller stuff ( coming from the oil pan )
 
Bet the fork is out of the drum.I have had it happen before,just got lucky and seen it.I keep it in neutral when putting the cases back together and guide the forks with long picks,A little grease in the drum helps keep them in place also.You could pull the basket and pull out the shift shaft and put it in place if you are good.lol.
Good luck
 
Back
Top