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Kitty kitty... RRRR
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1,712 Posts
Discussion Starter #1
Hi.

I ride for 4 years, and I generally like to know how do the things that I operate work, and that includes bikes. My previous old GSX-R750 had its filter/carbs disassembled to small pieces and brought back more than one time (not because I liked the idea, but I had to). But this time in the gearbox of R1 even competent mechanics are breaking their heads.. Maybe you can help me out though - or at least shoot some opinions and points I wasn't aware of.

It demands knowledge of R1 gearbox, though.. I hope there's someone that can answer me, so I'll post the story.


First things first - it's a '99 model, bought used, had a problem of 5th gear disengaging when under engine braking. As I was told earlier, it's a common problem on hard-ridden bikes (previous rider kept the bike in supreme condition in any other aspect, but rode this way for the last 1/2 year - and he's a very good rider). This problem is caused by fork wear - a small fork that holds 2 sprockets. Well, this fork is very problematic to get, since Yamaha importer here sucks. But I got it after 2 weeks of waiting - and it's for model '01. According to Yamaha's blueprints, this is the same fork. When the mechanics at my workshop assembled the gear, they put attention that these 2 sprockets, that travel from left to right and have pins on their side to engage another sprockets on the left and on the right side of the gearbox - they engage fully on the right side, but on the left they engage only by half the pin length. All the gearbox looks EXACTLY by Yamaha blueprints, nothing missing, all parts look in great condition, and after 5 assembling/disassembling sessions the problem stays EXACTLY the same.

Can someone please raise some idea - what can that thing be? The workshop already sent the prints to check abroad, but I'm not sure they'll manage it that quickly, and hope to help them..

Thanks in advance.
 

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Kitty kitty... RRRR
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1,712 Posts
Discussion Starter #4 (Edited)
This fork indeed moves on a shaft, parallel to the shaft on which the sprockets move.

The guiding pins on the fork go into the selector (a big drum behind the fork shaft which is operated by the shifting peg). One of the ideas from Yamaha was that the selector is worn out and doesn't push the fork as it should - but there are no signs of wear, and they don't have the selector in the country either, so I have nothing to check it against. My workshop manager prays for some R1 gearbox to open and cross-check - they're sweating on this thing since the beginning of the week.

When the old (worn) fork was put there instead of a new one, it caused exactly the same behavior - means this bike was ridden in that condition for a long while. I'm very sensitive to strange behavior, but I didn't feel anything out of ordinary, and one of the best riders that tested the bike before I bought it didn't feel anything either.

I hope I won't have to give up on this thing..
 

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Kitty kitty... RRRR
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1,712 Posts
Discussion Starter #5
Well, after all the buzz, 2 weeks of walking and going nuts, the problem was found and solved. The misalignment was caused by 2 non-original (2001 model, if I'm correct) sprockets that were installed in some point in the past, when the previous owner ****ed up the gear.
 

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You think you can keep up?!
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652 Posts
ando11 said:
good story. but how do sprocket changed screw up gearing? i want to change the sprocket on mine and i don't want that problem happening to me. thanks.
I think he is talking about gears in the tranny (not the external chain drive sprockets). If I am not mistaken Yamaha changed the tranny slightly during the transition between the 98-99 to 00-01's.

Is your bike back together yet? Does it operate properly now?
 

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Kitty kitty... RRRR
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1,712 Posts
Discussion Starter #8
Hi.

To YZFR1Freak : Yes, you're right. I didn't mean the external sprockets - I can hadrly imagine how is it possible to screw up anything in the transmission by changing them (but I believe in human abilities) :ugh
But the gear sprockets - inside the gearbox - were indeed the ones that got me into this nightmare story. The workshop manager was running around for 2 weeks, trying to get a gearbox for comparison from anywhere, including abroad.

I didn't get the bike yet, hope to get it tomorrow (a lower motor seal had to come from Yamaha representatives, and of course it was late too).
In any case, when I'll get the bike back and ride it enough, I'll tell if there's any difference in the gear behavior.
 
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