nightout
XS650 New Member
I have a 1981 Yamaha XS 650 and I bought a 5th gear overdrive from mikes. I told them it was too small tho and they say it will work. Is there something I need to do to make it work?
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Hey, nightout. You'll need to take precision measurements of the shaft OD and the gear's bore ID to figure out what's going on. Have a look at the threads in the "similar threads" listed at the bottom of this thread, especially the first one...
goodgollyjosh
XS650 Addict
I ran into this as well. I had to have mine opened up a couple of thou.
DEMORALIZER
XS650 Member
This happened to me as well. Dealing with mikesxs can be a pain. I went off what their listing says about the years and which one you need to get. Turns out you should just mic it first to see which one you will need. I bought the 78-84 gear cause mine is a 1980, but it ended up taking the 73-77 gear instead. My bike was 100% original with 2800 miles on it.
arod_1
XS650 Fan
To those of you that have successfully completed this swap, are you happy with the upgrade and would you do it again? I have my cases apart now and just can't decide if I would be better off with this or just dropping down a tooth or two on the rear sprocket. At least that way if I don't like it I can change it back easily.
I took mine to a machine shop with the original gear from the tranny and asked them to make the new gear's bore size the same as the old gear's bore size. A couple hours and $20, done.
I did both. Dropped 2 teeth on the rear sprocket and the OD 5th gear. Would I do it again? Yeah. These trannys are so close geared. Maybe because this was Mother Yammas first 4 stroke street bike and she was used to 2 stroke bikes. Maybe I prefer a wider spaced tranny because I wanted to run this bike on the highway at under 5500-6k rpm. Did I get what I wanted? Close, but not quite. Its still a GREAT "B" road bike!
I did both. Dropped 2 teeth on the rear sprocket and the OD 5th gear. Would I do it again? Yeah. These trannys are so close geared. Maybe because this was Mother Yammas first 4 stroke street bike and she was used to 2 stroke bikes. Maybe I prefer a wider spaced tranny because I wanted to run this bike on the highway at under 5500-6k rpm. Did I get what I wanted? Close, but not quite. Its still a GREAT "B" road bike!
DEMORALIZER
XS650 Member
I had no choice but to do my 5th gear overdrive because of my rear wheel selection. Im using a cbr250r rear wheel which uses a cushdrive and the smallest rear sprocket I could get was a 36. I had to opt for the 18 tooth front which is offset as well. Even with that done the ratio still wasn't close to stock. I would definitely do it again because it was so easy to do. If you are cracking cases open, then do it! Remember to mic the shaft before you order or you will be stuck with a gear you cant even use and shipping back to mikesxs and getting a refund isn't worth the hassle.
Yeah Mikes 
I'm pretty sure I have a mikes 5th in one of my "get this on the road soon" motors.
Since they are lying about the years, you's pay your money and take your chances. IIRC TwoManyXS1Bs did a comprehensive measuring series, late vs/ early, tranny dims changed the shaft/ gear bore dimensions. Gears/shafts "must" be used as a set, later gears are identified by a groove cut on the face of the gear teeth.
Some links to follow here, to get more info? https://www.xs650.com/threads/gearbox-inspection-opinions-please.64122/#post-794328
I'm pretty sure I have a mikes 5th in one of my "get this on the road soon" motors.
Since they are lying about the years, you's pay your money and take your chances. IIRC TwoManyXS1Bs did a comprehensive measuring series, late vs/ early, tranny dims changed the shaft/ gear bore dimensions. Gears/shafts "must" be used as a set, later gears are identified by a groove cut on the face of the gear teeth.
Some links to follow here, to get more info? https://www.xs650.com/threads/gearbox-inspection-opinions-please.64122/#post-794328
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Ive been bit more than once from Mikes. Maybe I better just wait on that 5th gear. Read first post and man talk about changes in the 650 tranny! Dont think I will split the case on MikesXS 5th gear. Should say buyer beware we dont have any idea on what this will fit good luck! 2 summers of chasing over hesting gremlins to find out it was Mikes Electronic advance.
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