Where to even begin...

Looked at the pictures first impression not that bad --good even

There is something odd black edge sticking out .. Cant remember seen it before Gasket ? not the stock head and matching cylinder ?
the head nuts seems there

1702329629706.png
 
I think you may actually have a 1980 model there, or at least the motor anyway. I don't see a points wire pigtail coming out of the points cover, and it has the later single outlet engine breather. You'll know for sure when you pull the points cover off, and the round alternator cover on the left side cover.
Yes, it's an '80 or newer engine... or at least it has the TCI sensor on the stator. That's (↓) the disconnect for it.



Untitled.png
 
Since you need the worm, you might consider "upgrading" to one from an XS400, the 1L9 unit. It's cable arm steps down instead of up like the 650's and, theoretically, that should make it turn smoother and not bind up as much .....

1L9XS400.jpg


1L9XS400-2.jpg


The female nylon part is the same, and of a later manufacture using black nylon. I think this is better, harder than the white nylon ones. If you decide to go this route, there's just one minor mod you need to do. See post #65 in this thread for details .....

https://www.xs650.com/threads/200-special.51454/page-4
 
The big thing about that is; it won't have an igniton advance rod or weights because that was built in to the TCI electronics.
Nor the camshaft being reamed to accept the advance rod bushings. That's fixable of course... but an extra step if going back to points.
 
Thanks for all the info guys. It's alot to chew on. With the left cover off I can now see where the clutch worm gear thing is supposed to attach. A whole new assembly is rather affordable (not at this moment of course but relatively 47$ is dirt cheap). I double checked the ID number across a few different charts to be sure. Comes up every time as a '79(can't be bothered to put the number here but it definitely started with 2f0). Based on what you've said and I've read it should by all means have points. However, as mentioned before a TCI unit did come in a cereal box with the motor and frame. Also, it looks like these spaces under the caps in the head should be populated but they're not. I ordered a book about these motors from Amazon written by some German guy. Supposed to have alot of pictures. Thanks for the link to the service manual its sure to get alot of use. This winter will essentially be a fact finding mission. What do I have and where do I want to go with it? How to get there? Etc. I have a basic concept but obviously things are going to have to change based on what is at hand. Sorry for the essay, everybody is sick so the baby doesn't sleep so the wife doesn't sleep and we all know how that goes.
IMG_20231211_210821045.jpg
IMG_20231211_210700787.jpg
IMG_20231211_210652826.jpg
 
Also, it looks like these spaces under the caps in the head should be populated but they're not.
Nope... not supposed to be. Pre-TCI, the right side had the advance mechanism and the left side the points. In '80 they went to the all electronic TCI (Transistor controlled Ignition) system. That replaced all the mechanical stuff under those two covers..... and that's why it looks squeaky clean in 'em, they've never been opened before.
 
Depending on the chart your looking at the 2F0 Vin #' could be wrong. 78E, 78SE, 79F, 79SF, 792F/SII and 80SG all start with 2F0. On the chart the 792F has the year with 1 year, (78), the document wouldn't allow me to rewrite over the original from 77-78 when it is a 78-79 model.

In this Vin Chart, (in colour) i have done a lot of research on model verified from members on here. Also has a fairly comprehensive model ID description
https://www.xs650.com/threads/xs650...workshop-manuals-and-other-information.30569/

The cam end looks smooth so it does indicate the bike may have been converted from points, but the advance rod bushing doesn't need to be removed so that makes it unlikely. IMM.

If the frame has a hinged seat then it is not a, 80SG and would, originally, b a points model

Edit: Jim posted while i was writing and makes a valid point about the cam covers have never seen any grease, so points to an original TCI Engine. Unless the Vin # matches, (frame/engine) then it points to an 80 engine at least
 
Last edited:
Thanks for all the info guys. It's alot to chew on. With the left cover off I can now see where the clutch worm gear thing is supposed to attach. A whole new assembly is rather affordable (not at this moment of course but relatively 47$ is dirt cheap). I double checked the ID number across a few different charts to be sure. Comes up every time as a '79(can't be bothered to put the number here but it definitely started with 2f0). Based on what you've said and I've read it should by all means have points. However, as mentioned before a TCI unit did come in a cereal box with the motor and frame. Also, it looks like these spaces under the caps in the head should be populated but they're not. I ordered a book about these motors from Amazon written by some German guy. Supposed to have alot of pictures. Thanks for the link to the service manual its sure to get alot of use. This winter will essentially be a fact finding mission. What do I have and where do I want to go with it? How to get there? Etc. I have a basic concept but obviously things are going to have to change based on what is at hand. Sorry for the essay, everybody is sick so the baby doesn't sleep so the wife doesn't sleep and we all know how that goes.
View attachment 257269View attachment 257270View attachment 257271

You wrote all this but couldn't be bothered to post a vin #. The most important bit of info to clarify what you have i not posted but your impressed with every one helping you. Reciprocate.
 
If that new $47 worm gear assembly is the one from MikesXS, I'd pass on it. None of the parts interchange with originals because the angle of the swirl is different. You're better off sticking with originals. The female nylon part is what usually wears but Yamaha used that part on many models so it's pretty easy to scrounge them .....

https://www.partzilla.com/product/y...?ref=8e57f4c772a5cf9e21585bf1f084074551846d34

My dealer has a boneyard out behind his shop and while there weren't any 650s out there, there were several 360s, 400s, and 500s. I scrounged the worms off of all of them, lol. In fact, that's how I discovered the 1L9 worm. I have it installed on both my 650s and I've supplied them to a couple of my buddies for theirs.
 
You wrote all this but couldn't be bothered to post a vin #. The most important bit of info to clarify what you have i not posted but your impressed with every one helping you. Reciprocate.
Don't mind skull he's just like that but a fount of XS knowledge.
Check the VIN on the front of the motor it's prolly different from the frame vin. From the factory the numbers match.
76 case.jpg
You'll need a new clutch push rod seal. The clean area under yours is from the oil leak washing off the grime.
1702387920206.jpeg

They're nearly always worn out.
 

Attachments

  • Under LH cover.JPG
    Under LH cover.JPG
    914 KB · Views: 37
All evidence points to the motor being from an '80 XS650SG. I suspect the confusion on the model ID is caused by A) the date on the steering neck being from the fall of '79 (typical of an SG) or B)the Title indicating '79 model yr. It was a period prior to the requirement for 17 digit VIN's and year-specific model requirements: states often titled bikes as the year of date sold. The definitive bit of evidence, as Skull & Gary indicate, is the full motor number; my bet is it is 2F0-2XXXXX
 
All evidence points to the motor being from an '80 XS650SG. I suspect the confusion on the model ID is caused by A) the date on the steering neck being from the fall of '79 (typical of an SG) or B)the Title indicating '79 model yr. It was a period prior to the requirement for 17 digit VIN's and year-specific model requirements: states often titled bikes as the year of date sold. The definitive bit of evidence, as Skull & Gary indicate, is the full motor number; my bet is it is 2F0-2XXXXX
Yep, my '80SG is titled as a '79 'cause it was made/sold in Oct that year. Never understood why the state DMV's did that. They certainly didn't treat cars that way....
 
If that new $47 worm gear assembly is the one from MikesXS, I'd pass on it. None of the parts interchange with originals because the angle of the swirl is different. You're better off sticking with originals. The female nylon part is what usually wears but Yamaha used that part on many models so it's pretty easy to scrounge them .....

https://www.partzilla.com/product/y...?ref=8e57f4c772a5cf9e21585bf1f084074551846d34

My dealer has a boneyard out behind his shop and while there weren't any 650s out there, there were several 360s, 400s, and 500s. I scrounged the worms off of all of them, lol. In fact, that's how I discovered the 1L9 worm. I have it installed on both my 650s and I've supplied them to a couple of my buddies for theirs.
I can SOOO totally attest to this.

As I've bitched about so many previous times in here...that Mikes worm gear isnt worth the time to try to package it and return it!

Piece of Chinese loose, sloppy, ill fitting crap that I took great pleasure in tossing in the trash bin in my shop. They should be ashamed selling something like that.
 
Don't mind skull he's just like that but a fount of XS knowledge.
Check the VIN on the front of the motor it's prolly different from the frame vin. From the factory the numbers match.
View attachment 257297
You'll need a new clutch push rod seal. The clean area under yours is from the oil leak washing off the grime.
View attachment 257298
They're nearly always worn out.
He says he has been checking the chart and it keeps coming up as 79, but...... can't be bothered...... to post it.,,.............

so yea I pointed that out after posting about 2F0's, links, that he needs to identify the vin and a certain way to identify the frame. In fact everything he needs except where the vin no is on the motor.

So yea I can b like that. Or I can delete myself from the thread,........
 
Depending on the chart your looking at the 2F0 Vin #' could be wrong. 78E, 78SE, 79F, 79SF, 792F/SII and 80SG all start with 2F0. On the chart the 792F has the year with 1 year, (78), the document wouldn't allow me to rewrite over the original from 77-78 when it is a 78-79 model.

In this Vin Chart, (in colour) i have done a lot of research on model verified from members on here. Also has a fairly comprehensive model ID description
https://www.xs650.com/threads/xs650...workshop-manuals-and-other-information.30569/

The cam end looks smooth so it does indicate the bike may have been converted from points, but the advance rod bushing doesn't need to be removed so that makes it unlikely. IMM.

If the frame has a hinged seat then it is not a, 80SG and would, originally, b a points model

Edit: Jim posted while i was writing and makes a valid point about the cam covers have never seen any grease, so points to an original TCI Engine. Unless the Vin # matches, (frame/engine) then it points to an 80 engine at least
There is no seat, but there's nowhere to hinge it from so I'm assuming there was no hinge on it. Numbers do match on frame and motor. 2F0-202362
 
Back
Top