XS850 Master Thread

Cool, thanks Franz.. the 850 is not 1:1, but definitely some good crossover with the xs1100 video.. should be helpful

I read somewhere the 850 must be pulled and split.. still need to do more research to be certain.

 

Let me know what you find, I am interested if it can be done. Good luck.

 

Ok, with 2nd gear gone, doing research and inspection on pulling gearbox assembly, engine, et al..

Phase I - Inspection:
Claimed XS1100 fix for "2nd gear pop-out" says this can be done with engine in frame (xs1100).. Multiple videos, blogs, forum posts to support... Cool!

Question... Can this be done, as equal, in-situ, on the xs850? Reports, perhaps spurious, suggest not. Let's see...

Phase I, Step 1:
Inspect underside/oil pan accessibility...

<Google Drive Video Link Here>

Appears, from the video, oil pan can be pulled without pulling the engine, and perhaps even wo pulling exhaust.

More to come, TBD, Etc., Et Al.

 

Found this little nugget on reddit.. sounds like 2nd and 5th gears on the xs750 (and likely 850) can com out wo pulling the engine or splitting cases..



Likewise, someone on xs650.com shared this video as well, where they pull the #2 gear wheel and perform the washer swap.



I'll be inspecting everything before I commit to anything. Stay tuned!

 

Ok, much to report on rectifying the xs850 2nd gear pop out affliction... (and more still to come...)

xs750 & 850 share nearly identical cases and transmissions, tho exploded diagrams call for some part numbers (supposedly) unique to each bike...

Attempting to determine if the 79xs750 2nd gear wheel (1J7-17221-03-00) is interchangeable with the 81xs850 2nd gear wheel counterpart (3J2-17221-00-00).

On the exploded diagrams for both bikes, the 2nd gear wheel interfaces with the identical 5th gear wheel (1J7-17251-03-00).

Based on what we know from this post (Yamaha Part Numbers Explained), its clear that the 2nd gear wheels in question share identical primary part numbers "17221" and the 3 digit prefix (1J7, & 3J2) should simply align to the model code for when this run of parts was produced. 1J7 = xs750, 3J2=xs850.

Given this information, I posit that Yamaha part# 1J7-17251-03-00 and 3J2-17221-00-0 are completely, drop-in, interchangeable.

So... Based on the above, I acquired a NOS/NIB 1J7-17251-03-00 gearwheel in the hopes of matching it to my xs850.

I "think" this xs750 2nd gearwheel is going to be a direct drop in replacement for my worn out (xs850) 2nd gear.... Starting teardown of my bike tonight.

The 2nd gear wheel in question mates to the 5th gear wheel and I have NOS examples of that on order as well.

For posterity, below I've outlined the dimensions of this NIB/NOS xs750 2nd gear wheel...

Follow-up drawing of the xs850 2nd gear wheel counterpart, 3J2-17221-00-00, pending disassembly of my 850.



This lil fellar spent the last 45 yrs waiting patiently, on a dealer shelf in central Louisiana. Thanks Natchitoches PowerSports!


Edit/Followup.. A FB user posted this excellent photo and I added some details that clearly identify the issue these bikes face with 2nd gear pop-out. (Pictured below is the 5th gear wheel that interfaces with the 2nd gear wheel pictured above)

 

Ok, here is the 850 2nd gear wheel (3J2-17221-00-00).

My suspicion from the previous post, that the 750 2nd gear wheel could be dropped in, was partially incorrect. the 850 2nd gear wheel has a smaller ID and includes a press-fit bronze bushing.

The 750 wheel (above) is also a hair thicker & is offset to the outside, with a relief pocket on the inside side face to accommodate the washer that people usually swap to the outside in the "washer swap" mod.

On the 850 the washer is already on the outside and the gear has zero offset.




Given the 750 gear has a larger ID, a bronze bush could be turned and press fitted into the gear so it will work on the 850 shaft. The 750 gear is still slightly ticker than the 850 and so on assembly we could either omit the outside washer, or use a surface grinder to take down the offset boss that is slightly proud on the 750 wheel.



Here are a few closeups of the wear on my xs850 2nd gear wheel dog faces.

 

Jesus clip never heard that name for the circlip.

 

My best guess is he thinks they look like prayer hands... ¯\_(ツ)_/¯

 

More to share..

This is the 5th gearwheel (1J7-17251-09-00) that mates with the 2nd gear wheels from the previous posts.

This specific example is revision 09 of gearwheel 1J7-17251. None of the partzilla or other North American parts diagrams for the xs750/850 call for this specific revision.

All the North American diagrams call for Revision 03, (1J7-17251-03-00), & probability is high that revs 09 and 03 are interchangeable.

I could be wrong & we'll know soon enough.. Enjoy!

 

So you should be able to use these parts with no machining?

 

Ok.. Good question, Franz.. Thanks..

Short Answer:
For the 5th gear wheel (1J7-17251-03-00, 1J7-17251-09-00)... Yes, I suspect no machining will be required, and this component --may--be-- drop-in compatible for any xs750-850 bike (TBD, pending further research).

Concerning xs750/850 "2nd" Gear Wheels, 1J7-17221-03-00/3J2-17221-00-00:
As detailed in above posts, the 79 xs750 2nd gearwheel (1J7-17221-03-00) (as confirmed) is NOT directly "drop-in" compatible with the 850 bikes. The 850 calls for the 2nd gearwheel "3J2-17221-00-00" and ID on this 850 gear is smaller than the counterpart 750 gear (as well as other differences, as outlined above, see above).

In regard to the xs750 2nd gearwheel (1J7-17221-03-00), as proposed, a bronze bushing can be turned and pressed into the 750 2nd gear wheel (1J7-17221-03-00) to attain compatibility with the 850 transmission, & matching ID of the 850 2nd gear wheel (3J2-17221-00-00) (this is what I will attempt to do, bronze bearing stock on order from mcmaster -- other variables at play, as well -- stay tuned).

Concerning xs750/850 "5th" Gear wheels, 1J7-17251-03-00, 1J7-17251-09-00:
The most recent post, above this one, is about the 5th gear wheel on the xs750/850 (which mates to the 2nd gear wheel (also detailed above))... dimensions and details for this NOS example of the "09" revision 5th gear wheel are detailed above. In theory, this "09" rev should be drop-in compatible on any xs750/850 bike. (TBD, watch for follow-up posts below for confirmation)

Thoughts:
Each year/model example of these bikes (at least in north America) calls for the gearwheel "1J7-17251-03-00"... (Thats Revision 03 of gearwheel 1J7-17221 (installed in my bike, pending de-install)). I suspect the "09" revision may have been specific to EU or A/PAC skus (for some reason, still not clear at this time).. I suspect gearwheels "1J7-17251-03-00" and "1J7-17251-09-00" should be completely drop-in interchangeable.. TBD

Stay tuned.

 

Just be aware that "revisions" could be due to any number of issues, a change in the supplier, some change in the physical casting, a change in machining/metallurgy/coating/finish, etc. It may be a "change" that is neither visible nor testable w/o laboratory-grade equipment.

Or it could be immediately obvious.

In my experience, Yamaha is pretty good at ensuring backward-compatability in revisions of major parts.

 

I always thought it was called that because of what is said when it flies off the pliers and into the far distant corner of the shop under things. As in "Jesus, where did that thing fly to?"

@slackard, delightful, Kevin Cameron style write up on your exploration of the XS850 transmission. Did you consider having the worn lugs on the old gear wheels welded and re-machining them?

 

Makes sense.

 

Welding and re-machining is likely ill advised since these gearwheels are induction hardened. Any welding would take the temper/hardness out of the HAZ and could lead to an unstable, soft or brittle part. To do this properly, one would need to re-harden and re-temper after welding/machining. Few shops are setup for or have the necessary experience to do heat treatment correctly, and in a 1-off custom job like this..it would be astoundingly expensive to have it done right.

Lets say we ignore material hardness/temper... We could build up some weld and would need to machine/grind it back to original dimensions & original tolerances... Work holding then becomes the next big concern.. perhaps with proper-sized mandrels, in a 3jaw chuck, on a rotary table, on a knee mill, one could attempt this type of machining with some degree of precision/repeatability.. In theory all the dogs should engage at the same time... and all these angles, radii and undercuts would make it a very difficult job to do correctly. If done poorly & out of tolerance, you risk loading up a single dog and snapping it off because the others are making zero contact and doing zero work (or worse).

Sourcing original (not worn) parts is the ideal path forward.. With luck the 750 specific 2nd gear wheels can be adapted to the 850. Will report back when I have more info to share!

 

Delightful explanation of why not weld and re-machine. A plain and yet technical reasoning. Thank you.

 

Getting late and didnt want to get into a whole thing here.... Just wanted to share this little nugget..

Manual states, "use deep 32mm socket to remove the clutch boss nut". No mention of just how deep...



Lots more photos to post, coming soon!

 

Details below on the very important XS750/850 "Clutch Holding Tool".

 

What's the part number for it .

 

Is that mig welding, it looks neat.

 

Where can I get some of that stock material? Grainger?

 

Thanks! It's TIG welded.

I get most of my mild steel and aluminum from the local steel distributor. They have drop-cut / hobbyist section, & I head over there every other week or so to pick things over.. usually $0.50/lb. (except when I bring donuts!)
Bronze or other exotic stuff i'll go through McMaster-Carr (not cheap, immediate shipping)
CoreMark metals will do small online sales, have good variety and will ship.. not cheap tho
OnlineMetals is another option.. even less cheap, depending on what you need.

Most mid sized cities will have some kind of local distributor serving local shops... If you call around locally (fab shops, steel distro house, etc..) just ask if they sell small drop quantity, or have a hobbyist/drop section you can pick.

A local fab shop sold me this steel pipe drop for a box of donuts... Never hurts to ask!

 

Do you do all your own welding and machining?

 

My family recently experienced a (profoundly understated) --*"MAJOR"*-- loss.

My uncle, Terry (see above), passed in a *GOD DAMNED TRAGIC* .... "FARM ACCIDENT", Oof, Age 84.
At age 84, Terry was going on 30!....Healthy *AF* & had *MANY* years to go.

(GENUINE TEARS AND SADNESS, PEOPLE!)

Terry was a skilled & storied "Tool & Die Maker".

The "Chat-Bot" says, "A good Tool & Die Maker was often considered the most technically skilled hand on the shop floor".

---THAT'S TERRY---

Terry gave a KIDNEY to my own father (his brother), and he was my machine shop mentor, FULL STOP.

I have leaned on & learned from Terry many, many, many times.

I know a number of other "Shop" folk, who I also lean on from time to time... Good people!

So, to answer you question, Franz....

Yes, for the time being, I do all my own shop/fab/etc work.... Old school and manual, to the extent possible.

I have a "day-job" / "co-worker" who is also a major contributor to my personal shop efforts (Joel, Clockwork Bikes).

Terry's loss will be omni-present in EVERYTHING I do, from here forward.

-- SHOP -- SAFETY -- IS -- NO -- JOKE -- FULL -- STOP --

 

@slackard sorry for you losing your uncle Terry in such tragic circumstances.

 

Interesting and startling discovery after getting the clutch basket off..

Pictured below is the bolt that holds the "middle gear drive" to the "axle drive" shaft.

On its own, this bolt backed itself out, bumping up against the shift shaft assembly.. Only 1 or 2 threads still engaged.. would have been a bad day if this bolt walked its way into a spinning clutch basket..

I am certain the basket has never been off. since the lock washer was as-new... Not good that this bolt backed itself out, it will def be getting some lock-tite when it goes back in!


Still working on getting the shifter fork shaft out in order to release the 5th gear wheel for inspection/replacement...

Big engine internals photo dump coming soon..

 

Starter clutch bolts have been known to back out too on the odd XJ.

 

Ok! Confirmed, the 2nd and 5th gear wheels do in fact come out without splitting cases.

With the oil pan and clutch off, the fork guide shaft (for forks 2&3) can be slid out after removing the e-clip from below. With the #3 fork off, the 5th gear wheel slides right off the drive axle shaft and out the side cover opening. The remaining gears are captive with circlips on the drive axle shaft. Maybe with a long nose snap ring pliers the other gear wheels can be pulled the same way..

However, there is also a carrier bearing on the drive axle shaft that these gears ride on which can also be removed from below. With the bearing off, the entire drive axle shaft / gear wheel assembly can be pulled & all gearwheels inspected/replaced as needed. No case splitting required.

Here are details on the 5th Gear wheel, Rev 03 (1J7-17251-03-00).. Rev 09 was already fully detailed above, tho I've updated the drawing here to clearly state the differences between revs 03 and 09.
Looks like rev 03 and 09 are fully interchangeable and they just clocked the dogs on the inboard side a little differently... for reasons?... I can see no reason why rev 09 and 03 aren't fully interchangeable.




Still assembling photos for a larger engine internals dump.. stay tuned!

 

Super to be able to fix it without case splitting.

 

No case splitting, and haven't even pulled the exhaust. So far plenty of room to work.

I still need to pull the bearing carrier mentioned in the previous post, tho, I am fairly certain, once out, the whole stack will drop easily.

Photos, et-al, inbound.

(Edit: I think Yamaha may have known these gear wheels would end up trashed and, at least in the case of the xs750/850, made efforts towards serviceability...)

 

Slackard you are doing excellent work here!

 

Some NOS items showed up in the mail today and among them is the specific 5th gear wheel revision 03, which called for in all the xs750/850 diagrams (1J7-17251-03-00), as discussed in the post above this one..

Interesting new findings.. Now suspecting the 5th gearwheel that shipped with the bike was not 03, as called for in the partzilla catalog..

I thought the revision I pulled from the bike was 03, since its whats called for in all the diagrams. However, now I'm not so sure..

So, to further clarify,

The OE/Pulled revision (now calling this revision 00) has dogs that are clocked at 0° to eachother. -- dogs are in phase.
Revision 09, that I detailed above has dogs that are clocked about 20° apart. -- dogs are 20° out of phase.
Revision 03, (which just arrived today) has dogs that are clocked about 50° apart. -- dogs are 50° out of phase..

Corrected drawings posted below.

REV 00, (as pulled from my xs850 motor). 0° Dog Phase:




REV 03, As inspected, NOS/NIB. ~50° Dog Phase:





REV 09, As Inspected, NOS/NIB. ~20° Dog Phase:





As for reasoning for the different phase angles? ¯\_(ツ)_/¯

 

Success! Here's the xs850 gearwheel stack out of the bike. No split cases, no exhaust pull.. So far pretty easy, besides research and mental prep.



As suspected the stack drops right out once the carrier bearing cap is out of the way. There are 2 things stopping the bearing cap from popping right out;
A: #2,3 fork guide shaft needs to be fully retracted to clear the bearing cap,
B: Oil pump needs to come out. 3 cap screws hold the pump to the lower case. Two of them are obvious and accessible as soon as the oil pan is off. The 3rd is hidden behind the pickup spout.. so. 3 JIS screws to remove the screen, then 2 small cap screws to remove the spout, then you can get at the 3rd fastener.

The gear dogs on the remaining gears also showing similar wear to the 2nd/5th gears that I already pulled.. Likewise the #3 gear fork is very worn.

I'm this deep already, and since everything is apart, I went ahead & ordered a complete set of NOS gearwheels & the #3 fork which was pretty worn also) Total spend for the 1-5 gearwheels+#3fork, $460.05
Total spend on the bike so far, including everything, purchase price ($200), registration, repair/replace parts, fully rebuilt brakes/MCs w new pistons & all new spiegler lines + a bunch of NOS/Rare spare parts that I'll keep in stock, $3,486.69

Doing pretty good so far and once buttoned up I'll have a basically brand new gearbox.

 

Great result.

 

Quick weekend update.. These transmission drive axle carrier bearing cap lock washers (2K3-15186-00-00) are NLA.. For posterity, documenting the dimensions here, and will be ordering fresh laser cut batch some time soon. I'll also need to make some forming dies so the flat laser cut blanks can be formed to match the originals.. Will post more on this as things progress.

 

The custom 750 ->850 2nd gear wheel bushing/mod is finished!

Def tighter tolerance vs the worn (23.3k mi) oe gearwheel.

My oil relief scratch pass turned up a burr, that I had to sand back by hand w 320, (Paul Brodie, & his student, "fine fingering", look it up).

I called it there, tho could have gone a few thou deeper for oil relief, shrug, 4tpi is wildly fast, even in back gear, oof (lathe people will know *eyeballs*)

Should be fine & nice thing is I have plenty of bearing bronze left over.
Thankfully, I also have another spare/untouched/NOS/NIB 750 2nd gearwheel in-stock, plus 2 NOS revs of the mated 5th wheel!

The bushing pressed in neatly (0.0015" press-fit) & bottomed against the shoulder perfectly.
The proud boss, on the 750 wheel, turned perfectly on the lathe 2-3 thou at a time (see previous posts for dimensions/detail).

So pleased! Still need to do final assembly & test flight... fingers crossed...

 

@slackard would it seize without the oil relief scratch and why use bronze? I don't have any engineering knowledge hence the questions.

When l rebuilt my 900f engine l noticed some of the main bearings three out of five had oil nozzles. Do you know why Yamaha didn't fit five of these instead of three? Do they increase oil pressure being restrictive to oil flow? I always wonder what the reason are for engineers doing things when designing machines.

 

Theses transmission gears see only a fraction of the RPMs that the crank & cams see, so the bearing surfaces are treated a little differently.

On the earlier 750, the transmission drive axle shaft end, where this gear lives, was a larger OD, and the 2nd gearwheel rode purely steel on steel (likely varying grades/hardness, tho still steel-on-steel), with some tolerance for an oil film.

The steel-on-steel setup isn't uncommon, tho seems poorly matched on the xs750 2nd gear & some reading points to the 750 shafts experiencing wear from the harder 2nd gearwheel..

On the 850, Yamaha reduced the diameter of the drive axle shaft end and pressed a bronze-clad bushing into the 2nd gear wheel (see photos above). In general, bronze is softer than steel. This grade of bronze has specific alchemy for shaft bearing uses like this, and it will wear first, (if wear occurs at all).

With the bronze bushing I effectively reduce the ID of the 750 gearwheel so it fits on the 850 shaft. With proper tolerance and oil relief, they should live happily together for a long while.

I added the relief grooves because the OE gearwheel bushing had little relief pockets as well (look close in the above photos), to capture and help redistribute oil over the bearing surface (wear prevention).. I'm basically mimicking the OE design with the tools available.

If the fit were too tight, and a constant/full coverage oil film were to break down, heating, wear and perhaps seizure could result... Taking all precaution, now, while everything is apart.

Edit:
The bronze bushing can also be pressed back out. So if there is wear, it's is replaceable.

Double Edit:
This was the first real project on the new 6-jaw lathe chuck.. More to come soon!

 

Havent seen the inside of one of those.. No idea what they were thinking... Those other 2 bearings are likely getting sufficient oil from other sources, etc. They may have tested it in a lab and decided they didn't need to drill those 2 extra holes after all...? ¯\_(ツ)_/¯

 

Super you can replace the bronze bushing and save the gear. So the relief grooves help retain oil like the cross hatching on cylinder bores keeping a thin film of oil between the parts. Great having the tools and knowledge to do this. Only time l used a lathe was at school fifty years ago.

 

One of the oil nozzles below the main bearing shell in the 900f.