later transmission work in a 72 256 xs650 engine

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theddrain

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well I'm about to open my case and get my crank out and i was looking to put in a 5th gear over drive and mikes xs only has them for 73 to 77 and later so will a later transmission in a early engine
 
Welcome to the forum, theddrain.

Yes, the early version MikesXS 5th overdrive is listed as 73-77:

http://www.mikesxs.net/product/05-0869.html

However, my parts manuals show that the mainshaft (driven by the clutch) is the same for 72 and 73. And the adjacent engagement gear is the same for those years as well. So, I see no reason why this overdrive 5th gear isn't listed as being useable in the 1972 transmission as well...
 
Funny this wasn't available when i was building my engine. Still isn't here in Canada. I Would like to have added it when i had the cases split. Not about to do it now.
 
I'm not sure just when they made the change but on the 256 engines there was a change in the tranny shafts. I think it was something to do with bearings. I think they changed the size of the shafts to use a stronger bearing.
I thought I had a tech bulletin about the changes.
But as TwoMany said the new 5th gear should work.
Leo
 
Hey, XSLeo! Yes, there was an obscure change to the mainshaft needle roller bearing starting with the early XS1, S/N S650-001235. The needle bearing OD changed, and this was accomodated by a change to the bearing pocket in the cases. The mainshaft remained as-is. A serious heads-up to anyone working with the early cases.

The BIG change occurred with the 1972 XS2, where the first gear ratio was changed, along with the kickstart gearing, which uses the 1st gear.

***************************************
XS650 transmission evolution
(work in progress)

*** Starting 1970 XS1, 256-parts

1st gear: 14t mainshaft, 31t countershaft, 26t kickstart
26/14 (1.857:1) kickstart ratio (See INXS thread on Kickstart)

*** Starting 1970 XS1, 256-parts, after s/n 001235

Change to mainshaft needle bearing OD, only cases changed.

*** Starting 1972 XS2, 306-parts

Change to 1st gear ratio
1st gear: 13t mainshaft, 32t countershaft, 25t kickstart
25/13 (1.923:1) kickstart ratio, harder to kick (See INXS thread on Kickstart)
Changes to shiftdrum, interchangability unknown. (to be done)

*** Starting 1977 XS650D, mid production at 1T3-721262

Changes to splines of both shafts and ALL gears.
Old shaft/splines have polished valley bottom.
New shaft/splines have polished spline tops.
5th gear shaft OD changed from 0.979" to 0.975"
5th gear wheel ID changed from 0.984" to 0.979"

Some changes to other parts, bearings and shims. (to be done)
 
@TwoMany.......that sir is a lot of work. But, it would be super useful. Especially as the older the bikes gets the more ebay'd and mixed the parts get...etc

That, perhaps it is? should be tagged somehow in a reference section here somewhere.
 
chizler62 said:
@TwoMany.......that sir is a lot of work. But, it would be super useful. Especially as the older the bikes gets the more ebay'd and mixed the parts get...etc

That, perhaps it is? should be tagged somehow in a reference section here somewhere.
Click to expand...

Thanx, chizler62. The impetus behind that OCD research was to support the future survivability of my 71's, so most of my interest and info centers around the '256' breeds. Since I have no hands-on experience with the later models (actually, any XS650 with an electric starter and hydraulic brakes), I'm hoping that some astute/experienced enthusiast will take that info and incorporate it into a larger/updated tranny evolution guide that covers the '447' and '533' revisions. One member here posted some very crisp/clear/detailed pics of his 'mystery' gears, hoping for some ID guidance, but I think that we were all at a loss to positively identify all those gears. An ideal future project, for someone with a treasure-trove of tranny parts...
 
Hi, everyone. I'm new here, but hav owned a 72 since 1976. just put it bac on the road last march since 1989. Ive replaced 5th back in 1980, when it disintegrated. Its popping out occasionally again.

Mike'sxs says that the bearings and seals fit all years. Is that a mistake?

Anyway, I just bought an 81 trans on ebay, (excellent shape $45), thinking that if 5th goes sour, I can replace it. With the info above, showing that Mikes is wrong, I don't need a newer trans.

I've emailed mikes about misprints, such as .985mm shaft, (obviously inches), but I never got an answer back. Not to put Mikes down, because Ive bought hundreds of dollars worth of parts and all were good and got here fast. Im relatively new to Mikes...

But, it seems that there are a lot of confusing mistakes.

I'll let you guys know if the 81 trans works in the 72. Any one?
 
Welcome to the forum, Marlin72xs. You've got a challenging project. There's numerous posts in here with members swapping out transmissions, but few details about the subtle foibles outside of that '77 transmission spline change. There WERE changes to transmission parts throughout the XS's production, but very little info on interchangeability. In your case, from XS2 to later '80s, the big unknown is the change to the shiftdrum. I have no info on its interchangeability/suitability to other transmissions. About the best I can suggest is to go through some of the service bulletins that cover transmission and shiftdrum servicing:

Yamaha XS1, XS1B, XS2, TX650 Tech Bulletins, Service Data, Brochures

Yamaha 1974-1979 XS650 Technical Bulletins
 
Thank you, toomany. And I enjoyed your dissertation on the transmission changes.

What about Mikesxs' trans bearings and seals that fit all years?

If what you say is true, that the 5th gear will fit in the 72, then I won't hav to worry about blowing 5th and scrambling for another. And $45 bucks for a trans is cheap and its in great shape.

And, with the engine open and on its back, I can easily play with the gears and shifting drum. Nothing like my old Beeser.
 
Best I can figure, except for that early XS1, there should be no problems with the bearings and seals set. However, some folks prefer using factory original bearings over aftermarket offerings.

Yamaha implemented a change, long ago, to the output (behind sprocket) seal, but only to the OD design to facillitate replacement without splitting cases, so not really an issue.

On your 5th gear issue. Something may have happened to cause your original to destruct, and should be caught before continuing. Typical trans work would include close inspection of anything involved in 5th gear shifting. Like:

The adjacent gear's dogs (known failure history), rounding of the dogs' corners.
Shift fork (unusual wear marks on sides, bending, guide pin to drum, guide rod bore, ...etc).
Gouge marks on the guide rod, for that shift fork. Check for straightness.
Shift drum, wear/rounding/chipping at the 5th's cam corner.

Yeah, horizontal-split cases will spoil you...
 
Thanks again two many, for the advice. I should have it out and upside down next week.
By the way, I'm pretty good at breaking transmissions. Broke my 305 scrambler trans twice. My 125 Elsinore once, and my XS once.

I'll let u know what I find. Thanks again.
 
Marlin72xs said:
Thanks again two many, for the advice. I should have it out and upside down next week.
By the way, I'm pretty good at breaking transmissions. Broke my 305 scrambler trans twice. My 125 Elsinore once, and my XS once.

I'll let u know what I find. Thanks again.
Click to expand...
Wow, marlin, you do know what the lever on the left does right? ...anyways, Some have reported the inner diameter is too tight to go on the shaft(the overdrive 5th), and must be machined.
Thanks for the heads up on the 256 trans, too many. mine is still rock solid, but now that I have a 71, im taking note of the earlier based threads.
 
In my defense Angus. The 305 Honda scrambler was only named a scrambler because of the up pipes. I broke the trans landing a jump twice. Yes I was a novice in 1970. The 125 Elsinore was broken by a kid who didn't like to use the clutch. (Little bastard). On my XS I was cruising at ~70, just after a short 100+ speed rush, and 5th just went away. I freaked. I sat on the side of the road for an hour or so smokin cigs wondering what to do. I finally began driving towards home in the shoulder slowly and imagining what would happen if a few hardened bits fell between the gears. Kablewy cases. I made it home ordered a gear and was riding in a week.
Hey, give me a break. 4 transmissions in 45 years ain't bad.

Well, I will definitely measure the shaft before I buy that overdrive gear. I still have a problem picturing how they add a tooth without changing the diameter.

Anyway, thanks for the info Angus.
 
Marlin72xs said:
... I still have a problem picturing how they add a tooth without changing the diameter...
Click to expand...

There's some tricks that can be done to 'diametric pitch' and to the 'involute' geartooth geometry. I found a short posting on this in a thread long ago, in a galaxy far, far away. Can't find it now.

However, my understanding of geartooth designs, and the comments from that poster, imply that the opposing/mating gear should also be redesigned so that its geartooth geometry matches. There's a recommendation on MikesXS's parts page to replace the mating gear for that overdrive 5th, but without sufficient description or explaination. I didn't see anything special about their listed mating gear, so I'm not sure what happened there...
 
To those concerned,

The 81 trans dropped into the 72 case perfectly. All bearings r the same size and it shifts on the bench properly. I will the measure both shafts where the 5th gear, (idler), goes, tonite.

I noticed that the original throw-out bearing only has a few rollers, but the mikes bearing has a bazillion.

Before the lower end goes back together, does anyone have any suggestions or measurements needed.

I see no noticeable bearing wear so far. Do you guys typically change all bearings anyway? If so, where do I purchase the OEM bearings?

Haven't done a rebuild since 99 on my Force outboard. Thanks.
 

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