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!