Splines.... Kudos for calling an engine an engine, though. I don't know where to find one,good luck.

 

The splines are fine for the sprocket. The threads for the retention nut are rounded off NOT the splines.

"The threads for the countershaft NUT..."

Please read the post properly before impuning my level of knowledge on the subject.
Thanks for the well wishes and bringing the possible confusion to my attention. See Edit.

 

Who, in their infinite wisdom, stripped the threads for the countershaft NUT?

 

Check craigslist. Lots of people parting out wrecked bikes. One will pop up eventually.

 

Some previous owner. There was evidently a recall for this issue due to the retention nut lock washer not preforming it's intended function. I just am glad the previous owner didn't get injured or worse riding at speed. Spoke to him and he rode the bike for three years without ever looking at it. Just one lucky dude IMO.

The bike has been worked on in the past and sometimes shade tree mechanics aren't always attentive to torque settings.

 

Here's my hammer suggestion. Since the engine is shut and the bike is 12 YO. That's what I would do. Get a new nut, new sprocket and chain. Put it all back together and for as good as you can clean up whatever thread you have left... get it tight, then tig weld the nut on the shaft. (It's shut anyway...) Then enjoy the next 10-12K miles on your bike.

That will give you

1. Plenty of time to find an engine
2. You could change chain & rear sprocket until the front sprocket is completely shot
3. Find a counter shaft. Keep in mind FZ6R & FZ6 use a very similar version of the same powertrain
4. Leave it like this and spend the $$$ on a new bike.

Honestly welding the nut is by far not the best solution. But you can buy a whole R6 for about the same $$$ that you will spend on an engine + time to fix it (Always end up needed other things)

Or.... http://www.ebay.com/itm/42871-Yamah...rbox-Shafts-/351098854280?pt=UK_Motorcycle_Parts_13&hash=item51bf1f5b88&vxp=mtr

Not that hard to swap. I did it before on a F3 engine... everything get out from the bottom.

 

+1 for having it welded.

 

Marthy, Thank you for your "hammer" suggestion. I did find that option on one of the R6 forums. I am concerned about over heating the shaft and melting the oil seal. I know that tig welding is cooler than the rest but I am still concerned about the heat. Also the fact that this bike is going to be track use only and I hope to get better on the track so more likely than not the bike will be pushed to its limits. I don't want the experience of catastrophic failure at 100+ mph. If I can't work out a better deal I will more likely that not to follow this advice.

Also thank you for the part find.

 

If you can give the nut some snug you won't need that much weld. Few small pass enough to hold the nut innplace is all you need. Go a bit at the time, seal are good up to 220F or so. I would put 2 or 3 good spot weld at 3 different place equally space.

Has a track bike you will be good for few season. Make sure you had a squirt of lube between session so it last longer. Make sure the sprocket sit nice and tight where It belongs. I would ride it like that personally.

 

One last thing. Disconnect battery and ECU! I heard of few ECU getting fried on racecars over the years... jusy don't take a chance.

 

I've welded a couple of lower timing belt gears on early miata 1.6 liter. Keyway slot in crank gets all worn and runs like poop. Line the gear up and mig the balls off it lol. Haven't had one leak. Or torching off press fit style pulleys. You'd be surprised what the seal will take. I've seen engines over heat to where the coil packs melted into the head and didn't leak any oil

 

Few tacks should do it... I wouldn't weld it out full... One tack at a time then let it cool... I don't think you'll burn out seal.. Just don't braze over the tacks afterward looking for weld ascetics, haha ;p

You could actually put majority of heat into the filler metal without getting crazy about base metal penetration.

 

So update: The kick ass guy's at Blackmans Cycle in Emmaus, PA were able to save the threads on the countershaft.
Meaning $45 in labor for the threads because the nut and washer are covered by the recall. So stoked. Wish I could go this season but good things come to those who wait. Now I have something to work for next season.