BS(Bridgestone that is, LOL) tranny problem

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skiri251

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OK.

This is the stuff which puts the forum into full swing. :hihihi:

As many of you know, I am a proud owner of 1967 Bridgestone Mark II RS (2 stroke 200cc twin).
I racked up around 700 miles since the complete rebuild. The last one being a spirited circuit run @ Willow Springs.
I managed to mis-shift (accidentally shifted down due to the reverse pattern from regular motorcycles), lock up the rear tire and crash. That by itself was relatively harmless. Very few scratches + bent shift pedal.

Two weekends ago, I went to the usual nearby twisty.

Then it started happening.
In the first gear, it feels like drive chain is skipping sprocket teeth. Sudden loss of acceleration with horrible noise. I really thought it could be worn sprockets so I put new front sprocket but it still happens.

I guess I have to split the crank case again but am afraid the cause will be not that self-evident.
It appears to occur only under power. I put it on the main stand and let the rear tire spin in the air but no skipping.
Never happened in other gears so far.

I posted this on Bridgestone forum but so far no replies.

So yet again I need great collective knowledge of this forum.

What should I look for when I open up the tranny?

BTW, here's the latest trim.

IMG_20161119_110905.jpg


IMG_20161119_110924.jpg
 
Didn't you have to find a special sprocket or gear in there that is plastic? Might be it was damaged?
 
[url=https://classicgoldwings.com/forum/viewtopic.php?p=184239#p184239:1w5ca5gb said:
slabghost » Mon Nov 28, 2016 11:50 am[/url]":1w5ca5gb]
Didn't you have to find a special sprocket or gear in there that is plastic? Might be it was damaged?

That was a timing idler gear. If that one slips, timing will be completely out and engine won't run.
This time I managed to limp home by short shifting in the first gear.
 
hmmm play under sreain sounds a bit big .... something got out of wack at the track id say and got worse it sounds ....best open it up .....cold something rather simple like shifting fork ...never know till you can see ...like a starter clutch ...it might just be poping out of gear ....
 
Thanks.
Well it only occurs in the first gear so misfire may be unlikely.

I just rode again.
It now really feels like the first gear wants to jump out of engagement.
Drained tranny oil. The first step of long and tedious process. (sigh)
I like to disassemble newly acquired broken bike but not the second time.
I guess I should try to enjoy..
 
Update:

Took two hours to dismount the engine.
IMG_20161130_154912.jpg

Took another hour to split the crank case.
IMG_20161130_171342.jpg

Not bad!
Tranny oil looked silverish and found metal pieces on the bottom.

Turned out to be a broken shift fork.
IMG_20161130_171321.jpg

Bought used ones for the day like this.
IMG_20161130_171522.jpg


Will be ready for a test ride the day after tomorrow. :yahoo:
 
Update:

Replaced the shift fork, put everything back together, and test-rode yesterday.
It didn't work...
I guess the slider (or whatever it is called) which shift fork pushes against is also worn.
Ordered used gear cluster from eBay.
One more try when it gets here.
 
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