1981 Basket Case Missing Some Parts...

irishlord99

Sometimes wrong, Seldom in doubt.
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So I bought a basket case '81 XS650 over the summer, frame was badly chopped, engine half dismantled, no exhaust etc. I could tell that the engine was missing a few pieces, including an exhaust valve and the camshaft... but hey, there's always ebay. The price was right and this is meant to be a learning experience for myself. I've rebuilt a motorcycle engine, but never re-assembled one that I haven't found whole.

My problem is that the book I have "The Yamaha XS650 Engine" is for an older model with points ignition and all the PDF manuals I have are either older models or the engine diagrams are so poor quality I can't make out what's what. I know, I need to by a clymer or haynes....

In the mean time, my question is this: I know that the points breaker doesn't exist on my model, I assume (but don't know for sure) that the governor doesn't exist either. Does anything go under the side camshaft covers at all? I don't have anything in my bucket of parts; but sometimes it's hard to know what's missing. Does the '81 have a timing shaft through the camshaft like the older models? Any help would be appreciated.
IMG_2143.JPG
 
I like the colors in the photo, nice looking bike there.

The US model XS650SH from 81 has nothing under those chromed chamshaft covers. They also have no timing advance mechanism so no shaft running down the center of the camshaft.

Enjoy your project.
 
Does anything go under the side camshaft covers at all? Does the '81 have a timing shaft through the camshaft like the older models?
No and no. It's electronic... timing trigger is on the crankshaft. Nothing in the top end... and welcome to the site! Looks like you got a real mess there;)
 
HERE You will find all the manuals and parts manuals for the XS650 and owners manuals for some models as well. The motor was the same from 74-83, so parts diagrams relating to the motor alone, from some of the earlier parts manuals, have better diagrams than the later 78-83 parts manuals. Just need to be aware the electrical components do change from 1980

Points ignition was on models from 70 to 79.........80 to 83 the points and components are replaced with a Factory Electronic Ignition with a pickup on the stator mounted about 2 oclock and the black box is mounted under the battery box.
 
Hi irish and welcome,
the good news is that it's possible to restore the rear suspension, perhaps with a BratStyle conversion kit.
Check that the dreaded PO didn't throw the TCI box away when he removed the stock battery box.
Putting a want ad in the list's classifieds will likely find you replacement engine parts.
 
You call it "badly chopped". If it's not what you want to work with you might be able to get enough out of parting it out to buy a different starting point... I would get the engine in good shape and make it real shiny, for starters :) Btw, you can easily retrofit parts in the head (with head still attached) to allow it to use points or Pamco, just for the option. The rear wheel is one year only and the best wheel by far in my opinion -- a rear disk is marketing, isn't worth the hassle, and cast rather than spokes lets you block the wheel from turning to make all kinds of work on the engine easier.
 
Well, the plan is to make a bobber out of it. I don't have the original tank, seat, exhaust, and God knows what else. I call it badly chopped because all he did was cut off the upper portion of the frame and hardtail down to the swing arm. I don't want a hardtail just for the lack of suspension, I want the clean minimalist look to go with it.

I have always wanted a bobber, but I don't have the heart to chop up one of these older Jap bikes that could possibly be restored... this one's far enough gone that I don't feel bad. I'm probably going to either buy an aftermarket hardtail; or cut the swing arm and foot-peg mounts out and just fab the rest of the frame in. Haven't decided yet. Engine is 1st priority. It would be nice to make it all shiny and new looking, right now it's black and yellow. :poo:

I will probably ride it with the frame re-done and the rest as is for a while, but eventually I want to build a springer front end and switch to spoked wheels etc. Right now time isn't my friend, so I'm just trying to get the engine re-built. The (dreaded is right!) PO left the engine with the heads and cylinder housing off of the lower end, and I have no idea what all might have gotten in there. So it's a total re-build as far as I'm concerned. Gonna split the bottom case and go through it piece-by-piece. After 36 years of life, I'm sure it could use a check-up.

TCI unit is there, painted yellow like everything else. :rolleyes:
 
Sounds like you've got what you need then. The shade of yellow is "Highway Department Yellow" in case you need more cans. Cool. As a final touch, you need to Helicoil the three studs on the front right valve cover for extra strength, but that's a ways away.
 
Regarding the 3 studs on the front right valve cover, is this a recognized fault on all XS engines??
 
The bottom one is prone to stripping the aluminum for sure. The upper two feel weak to me. It's probably harder on them if you use gaskets like I do instead of rubber rings. I believe some of the valve cover studs of the same diameter have different part numbers and longer threads.
 
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Hi irish,
I have to agree that the frame's suspension is beyond an easy salvage.
Replacing the integrated swingarm with suitable tubing will "add lightness" to the frame and improve it's looks.
Good that the TCI module was still there, even if it was painted Highway Department Yellow.
After painting both of my son's Hondas screaming yellow I got sick of that colour and switched to Astro Towtruck Orange
(actually Tangier Orange, a GM truck colour) on my XS11 rig

IMG_0128.JPG
 
It seems like I've seen HDY that glows like a reflector when light hits it. That would be a cool effect. Not to mention safe at night.
 
I like the lines of that frame but the way he set it up makes me wonder about the strength of that top rail in relationship to the swingarm mount. Is the swingarm bolted or welded? IMHO putting the top and bottom closer together weakens the strength of the frame by creating a greater "flex" point where the weight of the rider is. I dunno, just me rambling....
 
UPDATE: I've got the engine right to the point where I could split the case next. I took off the sump filter from the bottom side (all torn up!) and I'm looking through the engine to see what I can see, and thinking "this isn't bad at all!" There's no buildup of grime, shavings, etc. The last bike I split the case on, there was a thick layer of residue all over the nooks and crannies of the cases; but I'm not finding anything like that on this one. I'm re-thinking splitting the cases at this point. I was expecting to find a bunch of foreign matter in there, but it all looks pretty clean.

I don't mind going through with a full disassembly if need be, but is it really necessary at this point? I"m thinking probably not, but I'll wait to hear from you all before I start reassemby (gotta order some parts first anyway).

I like the lines of that frame but the way he set it up makes me wonder about the strength of that top rail in relationship to the swingarm mount. Is the swingarm bolted or welded? IMHO putting the top and bottom closer together weakens the strength of the frame by creating a greater "flex" point where the weight of the rider is. I dunno, just me rambling....

It is welded. Basically the PO just cut away the top of the original frame and hardtailed down to the swingarm. Kinda a half-assed approach in my opinion. Not sure of the structural question, it would probably be ok, depending on his welding skills.
 
Okay, a few things to check.

Inspect the conrods. Big end tilt, wristpin fit in the small end.

The rightside crank ball bearing is an inspection item. Best done with crank out, but you may be able to flashlight into it to determine race condition. Here's a worsecase example:
RightBearing.jpg


Can you see the pit on the inner race?

Examine the mainshaft's double-row bearing (behind the clutch).
You don't want to see this:
DblRowBrngFail.jpeg


Cycle the transmission thru all the gears, by slowly rotating the shafts and the shiftdrum's starwheel. What you're feeling for is positive, and symetrical, engagement of all gears. By symetrical, I mean that gear/dog engagements occur equidistant from starwheel centered/stopped positions. Non-symetrical could indicate a bent shiftfork.

Then, there's the seals. Probably age hardened...
 
I don't mind going through with a full disassembly if need be, but is it really necessary at this point?
If you're that close, I'd suggest you split it. As 2M points out, you can do a basic inspection as it sits... and you can replace the seals as it sits... but I'd wager that timewise you'd be ahead doing all that with it apart.
 
Who knows what the 2 center bearings look like if the outers look like they do! Where did those missing ball bearing go?
 
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