XS850 Master Thread

Hey Folks!

Proud new 81XS850H owner here. My bike is mostly complete, but not running. Presently sorting out electrical as I have voltage to the coils, but no spark & will post here with progress, etc.



In the past there were a couple sites dedicated to the xs750/850/1100 that are now defunct. Sadly, a lot of good info on these bikes was lost. As part of my learning process for this project, I've been digging up as many manuals and old docs as I can find.

Fortunately, this XJ forum is still here and these XS850s are very similar to the XJs & this forum has already proven to provide a wealth of information that has helped me with my XS850 so far... So, unless the mod's object, I'll continue to post about my XS850 project bike here.

I also re-drew the 850 wire harness so I can actually read it. PDF linked that below.
https://drive.google.com/file/d/1ltME7Haalzln_nmkipxKpJ4veYf_dRlj/view?usp=sharing

 

A recent, separate, thread covered the XS850 carb, which is the Hitach HSC34. It's a CV carb like the XJ's, just larger and also quite different.

Find more detail on the HSC34 Carb here: https://www.xjbikes.com/forums/threads/hitachi-h34c-carbs.122059/#post-687263

 

XS/XJ SERVICE BULLETIN:
There is a known issue with 1st & 2nd gears on these bikes where the gear dogs become worn and rounded.
This causes 2nd gear to pop out, especially under heavy acceleration. The issue is illustrated below.



Linked here is the full guide in PDF form:
https://drive.google.com/file/d/1GUevqs-LMGkY8Qjb7AKYthwaqQIm9WYU/view?usp=sharing

This is a repost of a guide that was hosted on XS11.com, recovered using wayback.archive.org.
All credit to the original authors.

 

The issue is with assholes doing clutchless changes.

 

Repost/Correction of broken link from above

 

xs850 Ignition coil relay mod went smoothly.
I now have really strong spark and starter cranks when even just barely touching the start button.
The coils and solenoid are now seeing battery voltage, instead of a 2-5v drop.

Prior to this mod, jumping the solenoid with a pliers always worked, but starting with the button was intermittent at best.
I could could see voltage and hear some clicking at the solenoid but it would only work & turn the starter occasionally & at random.
I cleaned and polished all the switches, connectors, etc., and still was seeing 2-5v drop depending where I was testing. along the path.
Now with this mod start button works every time and seeing battery voltage at every point in the system that is downstream of the relay.

Side note, I removed the Neutral Relay "in" wire from factory splice #2 (pictured above) and extended it all the way up to the yellow connector (pictured below), so now each component has its own dedicated full length trace back to relay pin 87.

I still need to tidy up and make the fuse arrangement permanent. Really happy with the result so far!

 

@slackard, good job! I have done something similar but simpler for my '84 Moto Guzzi California 2. Factory has the coil power going to the kill switch on the right control. A few years ago that gave up while not at home. A road side jumper got us home. Now with the relay in place it is much more reliable and runs much nicer. Funny what a good hot spark will do for you. I will have to investigate how similar your mod is to the XJ's. Thanks!

 

This is a correction of an earlier version. The 12R-01 relay is for the Neutral Safety circuit described in this bulletin

 

See above note, further correction, clarification, etc.

 

This is a revision to XS850 Service Bulletin #001 - Neutral Safety Circuit... A bunch of research, trial & error got me to this point.

12R-01 is the correct relay for the Neutral Safety circuit described in this bulletin, Yamaha part# 12R-81950-01-00.

This revision of Service Bulletin #001 now incorporates the clutch switch, which is part of this neutral safety circuit, & a corrected internal wire diagram for the 12R-01 relay itself.

Unlike the similar looking Headlight relay, this neutral safety relay's coil is energized by the R/W wire coming directly from the kill switch. In order for the coil to be grounded (and the relay switch closed) 1 or both of 2 conditions must met;
1. Neutral switch is closed (bike in neutral).
2. Clutch switch is closed (clutch lever pulled in)

If ether switch is closed, the neutral safety relay coil is grounded and the start button should work if all other wiring is in order. The diode inside the relay that connects to the Sb wire protects the relay coil from current back flow from the neutral dash light in the event the bike is in neutral (neutral switch closed) while the bike is running.

 

Repost of a corrected/broken link from above.

 

TLDR:
If there is a broken link you are looking for in this thread, keep scrolling as it has been re-posted in an updated / revised / more-accurate form, further down in this thread.

For the literate:
Heads up, clarification, etc.. I am treating this thread like a living-modern-pseudo-service-manual for the xs850 (as much for my own benefit as for the XJ/XS community at large). Above, and below, in this thread, will appear a number of broken image links. These links are INTENDED to be broken, as the original source images have been removed intentionally.

The broken links are on purpose, because, information in the broken links has been superseded, revised, or otherwise updated. This forum's tools don't give me the option to update posts >1h after submission, so by intentionally breaking the image links and reposting superseded information below, I can keep this thread reasonably tidy without also re-displaying inaccurate information as time goes on.

Enjoy!

 

A quick service note on spark plug wires and caps for the XS850..

The Coils are Yamaha part#4GR-81958-00-00 (Hitachi CM11-52A)

The Yamaha diagrams call for 2 different plug wire assemblies:
Long (qty1): 41R-82342-00-00
Short (qty2): 4X7-82341-00-00


The coil harness leads (red/white & orange wires) on my bike had all been cut, spliced and taped with electrical tape. It's a mess, adds resistance, and is definitely prone to failure. So, I got a set of what appeared to be unmolested/used coils off ebay for $35 shipped (Great deal!).

With the new coils I couldnt get any Ohm readings on any of the the 2ndary windings.. (should read 11.1kohm +/- 1.1koh, see the Coil diag graphic further up in this thread.)

Lucky for XS850 owners, the plug wires are replicable on these coils (not molded in like on the XJ). WHen i pulled the wires off and tested at the bare electrode i got good readings on each of the coils ~8kohm, so, wires and plugs shot, coils good!

Instead of searching for OE NOS plug wires for $$$, I just went to Oriley and paid 1.59 per foot of bulk 7mm copper core ignition wire (Oriley part# CC7N) (https://www.oreillyauto.com/detail/...-7mm-100-foot-primary-ignition-wire/std0/cc7n)



The OE plug caps were all pretty trashed too, & I found these caps that match the OE exactly for ~$5 ea. (NGK sku# L05EA, part#6667) (https://www.ngk.com/ngk-6667-l05ea-spark-plug-cap).




Total spend for 3 caps & 6' wire was ~$27.50 including tax, with plenty of wire to spare.

After installing the new wires and caps the 2ndary coils now all reading ~13kohm.. Maybe slightly out of the desired spec.. However after putting the new coils on the bike, my spark is visibly WAY hotter, more bright/white/blue, and girthier/fatter too... the old coils were throwing a noticeably weaker/narrow/yellow/orange spark (either bad plug wires, caps, or those spliced harness leads, or all 3).

I have yet to start or run the engine since I got the bike in Dec., she turns freely tho & has good compression. Since then I have been steadily laying groundwork for an easy start when the time comes.

 

Very exciting news.. NOS cockslap.. er... petcock, now in stock!! Part# 2G2-24500-05-00

Found this little guy NOS/NIB on a Yamaha dealer shelf in Alberta & it had probably been sitting there 40 yrs.



For parts like this, I will typically call a Yamaha dealer & ask them to search the dealer network inventory, then resort to ebay or amazon as needed.

I'm fine with an aftermarket or rebuilt component from amazon or ebay if it matches and fits and works.

In this case, the xs850 has 2 petcocks that are mirror images of each other (left and right) and the fuel/vac nipples need to point toward the engine.

No after market valve was setup as a left/right pair and hose routing would look very stupid with the nipples pointing the wrong way.

So.. although this wasn't cheap, $115USD shipped, I'm ok with it since the only other exact match, left hand valve for this bike is listed north of $200(ebay). Glad I called the dealer first!

 

Side note on the xs850 fuel valves...

There are two. Each are marked on the back with a big R or L.

Fuel Cock Assembly 1 (Right): 2G2-24500-05-00

Fuel Cock Assembly 2 (Left): 2G2-24510-05-00

 

Double side note on Yamaha Dealer pricing. Yamaha is AWESOME!

I also own & fix up an 85 BMW 535i.




Yamaha and BMW are both mASSive companies that have never been bought or sold or broken up. They have epic amounts of warehouse space, and dealer warehouse space in their networks, and have inventory that has been sitting on shelves for decades.

Bmw pricing on old inventory is insane. They sit on decades old, forgotten OE gear on dusty shelves & they refuse to sell for less than a small kingdom....I guess maybe they want to support the aftermarket bros? ¯\_(ツ)_/¯
(Those bros are def getting all my bmw cash, thats for sure!)

Yamaha wants to move inventory and will sell you NOS, OE gear at below aftermarket pricing...so yeah, Yamaha is awesome.

 

Further detail on the Flasher cancel circuit. Although part numbers may differ, these concepts apply directly to the XJ as well.

 

I randomly stumbled across an old XJ550 wire harness that was done up in Flash to be interactive.. You would mouse over a wire and the entire trace would highlight.. Brilliant!

Such a good idea that I converted my XS850 wire diagram to be "interactive" as well. Link below, requires a windows PC to run and is a standalone EXE file.

https://drive.google.com/file/d/1lYJ_naKANphQTehwerFu2VguLiK94CN6/view?usp=sharing

Screenshot below with Ground / Black wire highlighted:


Side note "Flash" on the web is dead, but you can still make self-contained EXE files to display flash content, which is what's provided in link above.
Getting this to work in HTML5 has been difficult & I may still figure it out (total html5 newb, & chatbot giving lots of buggy code), & not in a rush either.
Sticking with the self contained EXE for now. If you don't trust strange EXE files, Scan them at https://virusscan.jotti.org/, or run them in a VM to be safe.

Enjoy!

 

That is very nice!

 

Behold! An untouched (except by time) XS850 factory tool kit (#3J3-W2810-00-00). Sadly the "Oil level Gauge" and "Wire Hook" are MIA.

 

Those tools should clean up nice. Too bad the bag is in sad shape, looks like you were lucky it unsnapped.

 

Yeah, that snap was a lil tricky.. Got it open ok and then the bag took a little damage when I was putting everything back in... D`oh!

 

And doing them badly. It is an important skill to learn, but most teenagers (myself included back then) don't bother to seek out guidance from a master of the craft.

 

It won't in any way be original, but take the bag to your local leatherworker. They can use it as a pattern to make a new bag that will look the part and last far longer. Many can do the job with the original type of material if you desire.

 

These little Disc Brake Lock Washers (Yamaha #3H5-25834-00-00) are NLA, so here's a template PDF and DXF, for posterity.



If you send the DXF to OSHCUT.com and choose (.04" 4130 Annealed Steel) as the material, these are $10ea when ordering a set of 6. (Grand total for 6 was $59.20, after tax & shipping)
https://drive.google.com/file/d/1lYYS5-ZSdg03sBoC0Jh2sxQCUEix3Sm9/view?usp=sharing

If you print this PDF at 100% scale at home, you can use it as a template to make your own.
https://drive.google.com/file/d/1N9BSMLuCCMeBGCHuTihZkFfTAhuLo2N3/view?usp=sharing

 

These little Enrichment (Aka Choke) Plunger Caps (Yamaha #3J3-14968-00-00) for the HSC34 Carbs are NLA so here's a drawing with dimensions if you want make your own.
I turned mine on the lathe and they work great. I don't think 3d printing would be strong enough, tho happy to supply a STL if someone wants to try.
Also not opposed to making a few more of these out of aluminum, if there is any interest.. Let me know & Enjoy!


1

 

In the image directly above this post, you can see the HSC34 Idle Screw bore, (behind the choke plunger). Like most carbs from this era the idle screws were plugged to prevent "tampering". If you drill and yank the plugs on these HSC34 carbs, the bore points straight up & is open to the elements.. water dirt and debris can fall in & will stay there causing havoc.. So, to mitigate the issue I drew up these Idle Screw Plugs that are a snug o-ring fit into the idle screw bores & removable without tools. They use McMaster o-ring #9452K16. I haven't had time to actually turn these on the lathe yet.. sometime soon tho, since I dont want rain water or dirt getting down into those bores come spring.

Also happy to share a STL or whatever people want if someone wants to try 3d printing this... I assume a plastic print would eventually snap off in the bore, which is why I'll make mine out of aluminum & will post photos when able!

 

NOS|NIB Friday! Kind of excited about this one... last one on a dealer shelf in North America, probably been there since 1980. Thanks to Riverside MotoSport in Alberta, this relay is MINT!

$88.41 USD, shipped. Yamaha #3J3-83350-70, Signal Flasher Relay (Specifically designed to work with the Yamaha Flasher Cancel Unit, See XS850 Service Bulletin #004, above in this thread).

 

Welp, I started the XS850 this weekend!

Fired right up without any trouble at all. Initially after the carb rebuild I had the idle screw set too low, and after a quick adjust it started idling pretty well.. While it was at a low idle i could hear it chugging a bit and some clacking inside the clutch cover.. 99% sure i have the issue shown in the video below. I can feel the Primary chain is fairly loose reaching in from the oil filler cap, so suspect Ill need to replace that next.. Pulling the cover tonight to inspect further.



Couple other things I noticed during the test fire....

-Stator/rect/reg health all appear good & charging voltage at idle was ~13.9v

-major fuel leak at right hand petcock, rebuild kit on order.

-Still no headlight even when running.. possible bad headlight (easy to test) or bad relay, or some other nonsense (already replaced a bad diode (3H5-81980-00-00) that lives between the generator and the relay).

-tach response is sluggish and not accurate. seemed correct at idle, but when i revved the engine the tach would just slowly crawl up the numbers & would barely climb above 2k.. so, not seeing a 1:1 relationship between engine sound/speed and the tach.. its a mechanical tach & hopefully it can be repaired.

-throttle response was not good.. revved ok, but slowish to return to idle.. I dunno about these CV carbs (i went to church with them & internally (diaphragms, etc) looked good for their age)... Slide action was good on the bench & bench-sync'd with .010 guitar string. I'm sure some fine tuning is in order, hopefully nothing major.

The main issue is the primary chain clacking against the case... bike has ~29000 miles.. & they are supposed to last the life of the bike. (Edit: Only a single comment on the Primary chain in the service manual)


Let me know if any of you have seen or worked through these issues. Thanks!

 

Ooof! On close inspection, my OE front brake pistons are toast. Well...Some minor pitting on the polished surfaces was not entirely a deal braker.. What did me in tho, was the PO who ran the bike without pads or "caliper sleeve" & ground down the piston face.



As you can see, at least half of the piston face is no longer perpendicular to the bore, scored to shiat, and yea.. not good. (far from the first glaring safety issue I found on this bike)

Luckily tho, I found all new 316 stainless pistons at BrakeCrafters.com, & instead of effing around, I just bought all three pistons for this bike and will have zero worries going forward... I also qualified for free shipping when I added the 3rd/rear piston to my cart, so.. Almost free!

Chances are BrakeCrafters.com has most XJ brake caliper pistons & rebuild kits as well.

 

Following up on my Primary Chain post from above. I pulled the clutch cover & the chain is nowhere near as worn as the chain shown in the youtube vid I posted the other day, fwiew! Also zero wear on either the clutch bearing carrier or the clutch cover itself. The internal teeth of the chain appear in good order with no wear or excessive polish that would indicate skipping a tooth or anything like that.

23388miles on the Odo & seeing approximately 17mm of primary chain deflection, as measured right about even with center of the filler cap... I think for now I'm good, besides having torn the clutch cover gasket in one spot on removal (D`oh! gasket kit on order), & I'll button everything up as is.

I am fairly certain that this measurement could be made without removing the clutch cover.. The primary chain rides just below the oil filler cap and a narrow ruler could be stuck down there to take the reading, & there is plenty of room to get a finger in there to lift up and press down the chain to get a reading...just keep your other hand away from the kickstart lever while poking around in there!

So, if you own an XS850 and take a primary chain measurement as I described (through the filler cap), a reading of 16-18mm indicates the chain is right about mid-life, with lots of miles left to go. If your reading is >20 or 25mm, there is a good chance the chain may start wearing down the clutch cover and bearing carrier.

 

How lucky.....you get the starter clutch and primary chain on the outside of the engine!

 

I'm not sure why they did it this way.. an evolution of the XS line I suppose.. taking ques from Harley or what the British were doing.. Every other bike I've owned was like the XJ (or most any dirt bike) with a direct gear primary. ¯\_(ツ)_/¯

 

For posterity.
Functionally, this is just a dust cap for underside of the brake caliper pivot. Not exactly essential equipment, but will help prevent corrosion, etc inside the caliper pivot if you are riding in the rain, etc.

Happy to make & ship 3D prints in PLA, & able to share the STL if anyone is interested in making their own.. Just let me know!

 

Update to previous post..

In addition to models called out on the print above, this Caliper Pivot Bore Plug (2G2-25916-00-00) also appears on diagrams for the following bikes:

1979
RD400F
XS750SE
XS750SF
XS1100S

1980
XJ650G
XS400SG
XS850LG
XS850SG
XS1100LG
XS1100SG

1981
XV750H
XJ650H
XJ650LH
XS1100SH
XS400SH
XS850LH
XS850SH

1982
XJ650J
XV750J

1983
XV750MK
XV750K
XJ650K
XV920K
XV920MK

 

This little Paint Masking Cap came in really handy when it was time to paint the XS850S front brake calipers..
This quick 3d print saved an hour or more per caliper of tricky masking in the tight recesses of the caliper casting (versus using traditional masking tape & a knife).
Again, happy to provide these for anyone interested!


(I looked back and sadly no good before/after photos of these caps, they worked great tho!)

 

Update on the Disc Brake Lock Washers (Yamaha #3H5-25834-00-00) from a few posts back.. the first batch came in from OSH Cut and they turned out perfect. There was a tiny burr and minor scorching, leftover from the laser, that buffed right out on a wet-stone. Once polished and cleaned with acetone, I used "Gun Blue" aka Cold blue (Selenium Dioxide) for some corrosion protection and to give them the OE oxide look. A few minutes soaking in gun blue, rinse with water and dry, then straight into an oil bath to make the finish permanent. This Old Tony did a great segment on cold bluing if you're interested. (ToT Cold Blue Vid)
Again the material chosen was .04" 4130 Annealed Steel, & as before, I'm happy to provide these for folks in need, just let me know!

Here they are, fresh out of the packaging & next to the originals pulled from the bike.


Here they are after a quick deburr & polish on the wet stone, and an acetone wash to remove any residue. This is right before going into the gun blue bath.


Here they are after the oil bath, ready for install.


And here they are, installed on the bike. I torqued each bolt to spec (14ft/lbs), then a hair further as needed to square up with one of the tabs.

 

Looks like your start/stop point on the tab. What kind of laser?

 

Sweet! If you can, it would be great if you could post them here:
https://www.xjbikes.com/forums/forums/xj-3d-printing-stl-files.40/

 

I sent these out to OSH Cut.. I assume its a fancy/industrial Mazak O2 laser or some such..
At qty6 these were ~$10 ea/shipped & had them in about 5 days. See the previous post for detail.

Theses parts aren't specific to the XJ and are specific to the XS850 (granted, some other bikes as well), hence posting here (& not double posting). If I have anything that is specific to the XJ, I'll post it there.

 

For anyone who cares, this O-ring (Yamaha #2G2-W0044-00-00) is NLA from Yamaha, & serves as a dust shield & vibration damper for the pivoting "2G2" caliper described above...Standard equipment on the XS850 "Special" models and other bikes with the 2G2 caliper (also listed above). This is a basic metric o-ring, readily available from amazon, etc. OD 21mm, ID 14mm, Thickness 3.5mm.


Also, side note.. and for anyone with a heart. This man, Terry, lost his life yesterday, at the grand old age of 83. This man, aside from being my shop mentor & favorite uncle, was the best of you all, and you should all hope to aspire to his abilities and his character and quality of life. This man is a genuine HERO.

He gave a kidney to my own father, SAVING HIS LIFE, when I was a boy. Tragically, Terry burned up in fuucking farm accident/tractor fire yesterday afternoon. Story goes tractor (old time FarmAll H) was running rough after hauling brush at his son's (my cousin's) hobby farm. I guess they stopped to work on the carb.. he pulled a fuel line and gas sprayed him along with the hot manifold & my cousin was burned too, trying to put out the fire. FUUCK SAKE. I shit you not.

This man was my --actual-- HERO!


You can see how happy he is making chips on the mill.... This is hardly a tribute. I actually forgot I had emotions. FUUCK.

 

Was able to fire up and drive the xs850 for the first time on friday.. engine is really smooth once fully warmed up and super pleased about that.. All systems are go and its pretty much a sorted bike now.

EXCEPT... The kick in the teeth is that 2nd gear is completely gone, except for light engine braking.. otherwise it pops out immediately. Still rideable if I hold first a little longer and skip straight into 3rd... however, looks like I'll be splitting cases some time soon. I know XJ's are prone to this failure mode also.. any advice or links for splitting the XS850 cases is most welcome! Not a ton of resources out there on these bikes, especially deep engine stuff.. Will document as much as possible.

Side note, anyone sitting on a good condition xs850 gear set? any known crossover from other bikes? Much Obliged!

 

You can access the gearbox on the XS1100 with the engine in the frame. Don't know if it can be done on the 850.