Countershaft splines stripped

Hey everyone - unfortunately a friend took my bike out for a ride and didn't notice that the front sprocket had broken, leaving the splines on the countershaft completely stripped. I was wondering if anyone had any input as to whether this would require a rebuild/new engine or if I might be able to get by for a while welding a new sprocket to the countershaft. Any ideas as to how extensive and/or expensive this damage is? Bummed out  :thumbsdn:

 

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You have to split the cases to fix that.new shaft is required. You could tack weld a sprocket on for the short term but if it were mine I would buy a new or used shaft and put it in.you would be looking at a lot of labour to do the job right.

Please do NOT weld a sprocket to a countershaft, repairing that is pretty extensive, it requires dissasembly of the engine and splitting the cases, you may be able to find a new counter shaft & swap the gears over, or possibly an entire transmission assembly from ebay, that is the only method of repair I know for a damaged countershaft, I don't believe the splines are on any replaceable part, but I may be wrong

How good are you with tools?  Could be done for $100 plus the cost of a shaft assuming you do not have to buy a lot of tools to do the job.  Flywheel can stay in place.  Case splitter can be improvised from a 2 jaw puller frame.

 

Welding a sprocket is obviously a last resort but it has been done before.  I don't recommend it, probably just result in more problems.

Thanks for the input... I'm not great with the wrench, unfortunately I don't really have a lot of experience. How difficult is it to swap the complete bottom end assembly? I see a number of them on ebay, but there's a lot of variety in price, on the low end from 265 (e.g., http://www.ebay.com/itm/2001-01-DRZ400E-DRZ-400E-DRZ400-400-Engine-Motor-Bottom-End-Crank-Cases-Tranny-/121168685173?pt=Motorcycles_Parts_Accessories&hash=item1c36376875&vxp=mtr ) all the way up to around 600.

Thanks for the input... I'm not great with the wrench, unfortunately I don't really have a lot of experience. How difficult is it to swap the complete bottom end assembly? I see a number of them on ebay, but there's a lot of variety in price, on the low end from 265 (e.g., http://www.ebay.com/itm/2001-01-DRZ400E-DRZ-400E-DRZ400-400-Engine-Motor-Bottom-End-Crank-Cases-Tranny-/121168685173?pt=Motorcycles_Parts_Accessories&hash=item1c36376875&vxp=mtr ) all the way up to around 600.

The difficulty level is hard to say.. For me... a few hours bike on lift to bike out of the shop.

 

For you????? 

Perhaps read through the FAQ article on installing a big bore kit.. essentially that is what you'll be doing in swapping out a bottom end. 

DRZ Big Bore Install

 

You also need to consider replacement of the top end (piston and rings, deglaze the bore, or install of a 94mm BB kit) while it's apart.

 

And to the question of a used bottom end.... it's a crap shoot. unless you know how

 it was used, how it was maintained, if it's been apart before, how long has it been sitting open, was it properly prepped before storage. 

 

On a used bottom end with no known history from a trusted source, if I was doing it for myself.. or someone that wanted a totally reliable engine with no surprises I would split the "new" cases and inspect all, and put a Hot Rods crank and bearing set in it. 

I don't recommend it but I welded the nut to the shaft and the sprocket to the nut. Ran it 800 miles then figured I was pushing my luck. Was a easy grind to remove.

Why not weld a new sprocket to the shaft as a temporary fix? The shaft is beyond repair anyway. Weld a brand new sprocket on and ride it until sprocket is worn out. Save money during that time and then do a rebuild with new shaft.

Why not weld a new sprocket to the shaft as a temporary fix? The shaft is beyond repair anyway. Weld a brand new sprocket on and ride it until sprocket is worn out. Save money during that time and then do a rebuild with new shaft.

i agree.. How hard is it to take a cut off wheel or grinder to the welds.. It's already jacked up anyways. That's what I would do

It would be technically possible to build it up by welding and remachine the spline if you could find someone to do that. It would probably have to be heat treated afterwards to return it to whatever hardness it should have, which is a much more difficult task than the first two.

i would split the cases and do the wide range transmission while it's apart. 

 

not knowing what the shaft is made of, or it's rockwell before (or after) the welding means it's a no-go for me. and killing the oil seal...

 

besides, having the wide-range transmission would be a nice thing to do at the same time as fixing the shaft properly. 

It would be technically possible to build it up by welding and remachine the spline if you could find someone to do that. It would probably have to be heat treated afterwards to return it to whatever hardness it should have, which is a much more difficult task than the first two.

It's technically possible to have a new shaft turned, ground and hobbed, then heat treated from scratch.. but the OP is in Illinois.. not the middle of a third world country where a replacement output shaft can not be had in just a few days new or used found hundreds of sources.  expending the time or energy to remove that shaft and "fix" it is just kind of silly in reality.. .. Though an interesting idea and project if there was no other choice.

It's technically possible to have a new shaft turned, ground and hobbed, then heat treated from scratch.. but the OP is in Illinois.. not the middle of a third world country where a replacement output shaft can not be had in just a few days new or used found hundreds of sources.  expending the time or energy to remove that shaft and "fix" it is just kind of silly in reality.. .. Though an interesting idea and project if there was no other choice.

 

It's all about locality. I'm a machinist in Norway, which is a first world country in the middle of nowhere. My best guess is an output shaft is 2+ weeks away. I wouldn't really want to put any homemade engine parts in my own bike either though, but I've seen a lot of weird stuff in here. 

Split the cases, remove the output shaft, then have someone hard weld and machine the splines back in. Any decent machinist should be able to do it. Price could be an issue, or you could just buy another output shaft of eBay or the manufacturer. Also, make sure you give your friend a few knocks haha

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