2003 r6 - No Power to drive sprocket - clutch / transmission help needed

[g-ram]

Posting for a friend, his thread is at:
http://www.r6-forum.com/forums/showthread.php?p=2565948

2003 Yamaha R6 35,000 Km on the bike, no engine mods, well kept bike. Driving along, went over rail road tracks and lost power to drive sprocket. coasted onto shoulder of the road. When I restarted my bike, engine started as normal, however when I pull in the clutch lever and shift into 1st or 2nd, the neutral light goes off to indicate i would be in gear, however no power to drive sprocket is given. Can rev the engine to it's fullest with no power while in what appears to be 1st or 2nd. I also tried all my gears doing this.

I disassembled my clutch and there are couple small burn marks as seen in the picture, however I am not sure if this is the complete problem and am looking for some help ?

Sidebar - the small chain in behind the clutch basket seems to be extremely loose and am wondering if this has any relation to my problems ? approximately 1 cm of free slack.

 

[invictus43]

Did he take off the output shaft cover to see if the nut came off the drive sprocket? Otherwise, I think he's got some serious problems. Something broke in the transmission or the primary drive broke. I don't think the clutch is the problem..they don't go from good to bad just like that. It's possible it's not really going into gear..he just thinks it is..so it could be a shift drum, fork or detent problem. If it IS actually going into gear..and there's no drive..he must have broken the input or output shaft in the transmission.

 

[sircastic]

Did he take off the output shaft cover to see if the nut came off the drive sprocket? Otherwise, I think he's got some serious problems. Something broke in the transmission or the primary drive broke. I don't think the clutch is the problem..they don't go from good to bad just like that. It's possible it's not really going into gear..he just thinks it is..so it could be a shift drum, fork or detent problem. If it IS actually going into gear..and there's no drive..he must have broken the input or output shaft in the transmission.

+1 on the output shaft sprocket. The nuts on the R6's seem to disappear between 30-35k. Check that first, it that's not it you're in for an involved and possibly expensive fix.

 

[g-ram]

Thanks for the help guys, was the nut on the drive sprocket.

Lesson learned, KISS!

 

[invictus43]

Thanks for the help guys, was the nut on the drive sprocket.

Lesson learned, KISS!

Yeah..always start with the simple things..saves a lot of work and the most common stuff is probably what happened to you.

I also wanted to mention..Resist the urge to rev up the engine when you think it should be moving..if something DOES catch, you could have a little incident on your hands..

 

[RockerGuy]

Anybody have a pic of this? Is that the rear axel nut? That should be a safety issue

 

[invictus43]

Anybody have a pic of this? Is that the rear axel nut? That should be a safety issue

It's the nut that holds the front sprocket on the transmission output shaft. You can't easily see it on some bikes without removing the front sprocket cover or look very closely behind it.

 

[RockerGuy]

It's the nut that holds the front sprocket on the transmission output shaft. You can't easily see it on some bikes without removing the front sprocket cover or look very closely behind it.

WTF is wrong with Yamaha. Shouldn't that be a double nut with locktite?

 

[invictus43]

WTF is wrong with Yamaha. Shouldn't that be a double nut with locktite?

It's a single nut with a tabbed lock washer. If someone installs it incorrectly or if the lock washer is bent too many times, it may not last.

EDIT: I snooped around a bit and...it seems Yamaha is aware that some output shafts on some of their 600 products have incorrect machining on the countershaft sprocket retaining nut thread that doesn't allow enough engagement of the threads. There apparently is a TSB on the subject. So that might explain why so many go missing.

 

[BoostedR6]

It turns out I had this same problem last week. Not only did the nut fall off, but the shaft is stripped. Its stripped so bad that there are no threads left. Is it safe to die the shaft one size smaller with a new nut and lock washer?

 

[frekeyguy]

It turns out I had this same problem last week. Not only did the nut fall off, but the shaft is stripped. Its stripped so bad that there are no threads left. Is it safe to die the shaft one size smaller with a new nut and lock washer?
View attachment 29632 View attachment 29633

I doubt you can re thread that output shaft. Those are usually hardened....

Ive fixed a similar issue on an older yzf but there was enough thread on that shaft.

You might need a new output shaft.

 

[invictus43]

I doubt you can re thread that output shaft. Those are usually hardened....

Ive fixed a similar issue on an older yzf but there was enough thread on that shaft.

You might need a new output shaft.

I agree about the hardening. Also, to do it properly it should probably be out of the bike and on the bench..at which point..you might as well just replace it. I think he should look into getting Yamaha to do it if the mfg. tolerance issue is being treated as a TSB/Recall. He might get it done for free.

 

[frekeyguy]

I agree about the hardening. Also, to do it properly it should probably be out of the bike and on the bench..at which point..you might as well just replace it. I think he should look into getting Yamaha to do it if the mfg. tolerance issue is being treated as a TSB/Recall. He might get it done for free.

I did not know there was a Technical Service Bulletin on this....Yamaha uses a wavy washer with teeth. IF the teeth aren't aligned with the splines and the tabs bent over (i'd suggest using loctite too) THIS NUT wilL COME loose.

Its often to do with the service tech. who might have over looked or re-used this washer.

The sprocket in the picture below needs to be shoved towards the back, then the wavy washer installed, it will barely stay in place until the sprocket nut is installed.

There are some solutions to fix this issue....
1. Thread the inside of this shaft....get some washers and shims and hold the sprocket in place. (easy) Uses loctitle+lockwashers
2. If there are any threads left, put the washer + nut back on the shaft with a new sprocket, and drill/tap set screw into the shaft
3. Cut a retaining ring / spriral ring groove + use shims to hold the nut in place (motor might not have to come out, but watch that output seal) this will be hard to do by hand on the bike, but its possible if your careful and take your time.

 

[frekeyguy]

TO J-RAM and BOOSTEDR6 what is the pitch on your chain?

 

[sircastic]

It turns out I had this same problem last week. Not only did the nut fall off, but the shaft is stripped. Its stripped so bad that there are no threads left. Is it safe to die the shaft one size smaller with a new nut and lock washer?
View attachment 29632 View attachment 29633

Going by the rust on the output shaft splines the sprocket was loose for some time.

One other thought in addition to Frekyguy's ... given it's an 03 and the shaft is screwed anyway I'd be inclined to weld a new sprocket to the shaft. Not an ideal situation but with the understanding that if the bike lasts longer than the sprocket the next sprocket change will require shaft replacement (which is where you are now). It's a decision on spending money now or later on replacing the shaft. Welding needs to be done carefully as not to heat the shaft too much and damage the output shaft seal.

 

[frekeyguy]

Going by the rust on the output shaft splines the sprocket was loose for some time.

One other thought in addition to Frekyguy's ... given it's an 03 and the shaft is screwed anyway I'd be inclined to weld a new sprocket to the shaft. Not an ideal situation but with the understanding that if the bike lasts longer than the sprocket the next sprocket change will require shaft replacement (which is where you are now). It's a decision on spending money now or later on replacing the shaft. Welding needs to be done carefully as not to heat the shaft too much and damage the output shaft seal.

never welded...how much heat would it require to put a half decent bead around the sprocket + shaft? What are the odds that it might melt a lip on the seal?

Im curious to know.

 

[sircastic]

never welded...how much heat would it require to put a half decent bead around the sprocket + shaft? What are the odds that it might melt a lip on the seal?

Im curious to know.

If the splines are decent then all you're doing is holding the sprocket in place. Small welds (1/4 round at a time) and cool it in between works fine. It's a temporary fix, if it screws the seal then you're only out the cost of a sprocket in addition to the proper repair. I wouldn't suggest it on a newer bike but on an older bike the 25k you get out of a new chain and sprockets might outlive the bike.

 

[BoostedR6]

Yea I think Im screwed. With 57k on my bike. I think I should just get a new sprocket and put a weld on it. Either that or rip apart the tranny.
I called a Yamaha dealer about this recall, but it doesn't work for me because my bike was originally purchased in the States.

My friend also has an 03 R6, we took his apart to see if he had the recall done and we found a bent lock washer and a c-clip. He has 35k on his bike.