'79 XS650 Special Low-Effort Resto

POs, man... POs never change. I'd love to get my hands on the person who did all this damage to this bike. It's not just the bent up front end or the hilarious electrical bodge jobs I've run into, it's the layers and layers of filth on everything. Like, there's thick, fossilized mud caked on the bottom of the engine, still. I had to chip it away to find the drain plug. I've had the hardest time cleaning this thing because all the grime and dirt is baked on/caked on/stuck on. It's wild.
 
The protection sleeve is stuck on the original plug wire with a bead of glue. Spray WD40 in between the sleeve and wire then jam a length of old coat hanger down in there. Wiggle it around to break the glue bead free. It will remain in the sleeve but that's a good thing. Lube it up again to install on the new wire and when the lube dries out, the glue will re-adhere and the sleeve will stay where you put it.
 
Guess what! The bike's not finished! Not yet, at any rate. Turns out there were still some last-minute things I needed that I didn't know I needed, including some parts I already had that turned out to be for earlier XS1/2 models and some brake hoses that were too short! And, of course, the petcocks I had laying around for this project turned out to be junk and I had to buy new ones from Mike's. It's always that last 10% or so of the project that takes the longest, eh?

Mostly what I did over the past week was assembly stuff. Replaced all the right-hand crankcase accoutrement (brake pedal, kickstarter, foot peg) and installed the right-hand exhaust system. Bolted the airboxes back in. Found a permanent location for the reg/rec. Finalized the left-hand bar controls and grip. Swore. Threw tools. Angrily ordered parts. Etc. Etc.

Anyway, if the good lord's willing and the creek don't rise (again) I should have this thing running this weekend. Hopefully. If the parts get here. I'll keep you all abreast of the situation.
 
NEW PARTS DAAAAAAAAAAAAAAAAAAAAAAAAAAY
cijMT3Hl.jpg
 
Okay, so, yesterday was a good day. Got the brakes buttoned up, finalized installation of all the handlebar controls, rebuilt the air filters with new UniFilter foam and installed them, installed the new petcocks, installed the new cables, installed the new plug wires and caps, installed new alternator brushes, replaced the fuel cap gasket, started on cleaning up the wiring (including plugging everything in inside the headlight bucket) and did some light tidying/polishing.

I bypassed the reserve lighting unit, but now I'm seriously considering eliminating the light checker and safety relay. Mostly because they're ancient and I don't trust them at this point. Other than that, once the left-hand crankcase cover gasket gets here I can button up the left side of the engine and finally do the final assembly.

Oh, and random question: Why does this engine have one square tappet cover?
 
BSAKat said:
Oh, and random question: Why does this engine have one square tappet cover?
Click to expand...

Square cover is due to compression relief added with the electric start for 1972. Compression relief went away. The square cover remained for the duration of the model run. IIRC, only 1972 & '73 have the doohickey that raises the exhaust valve when the electric start is used.
 
Your '79 Special has the more complex 7 wire light checker. Power for the tail light passes through it so if you remove it, you'll need to put a jumper wire in the harness plug. Tail light power comes from the ignition switch and is fed into the light checker on a blue/yellow wire. It runs out of the light checker to the tail light on a blue wire. So, you'll need to jumper those two together to restore tail light power and function.

If you disconnect the headlight safety relay, you'll need to install a headlight on-off switch somewhere, or wire it directly to the ignition switch so it comes on with the key. But I don't recommend that. With the headlight on all the time, you'll be stealing battery power from the starter and ignition. These bikes don't have a very big battery so there's not much of a power reserve. Run the battery down some and the starter may still crank but there may not be enough power left over to run the ignition. Having the headlight on will only aggravate the situation. That's why I install headlight on-off switches on mine.
 
Ugh, I'll just leave it, then. I know the light checker works because I have power to the taillight. I'm not sure about the safety relay because I haven't started the bike since last October and it didn't have a headlight in it at that point. I think I'll temporarily hang the left-hand exhaust so that I can start the bike today and check the lights and turn signals. Man, I know I shouldn't be, but I'm still constantly amazed at how substandard these charging systems are.

Oh, real quick - I did run into a little wiring conundrum last night that I'd like some advice on. I ended up buying a new right-hand handlebar control box with the start button and kill switch (none of the ones I had were worth sprucing up), and it has a four-wire connector: Red/White, Red/White/Blue/White, and Black. Thing is, the bike's loom has a three wire connector with just the striped wires and no black/ground. Clearly the switch box needs a ground, so what do I do here? Do I cut the black wire out of the switchbox's connector, slap a male terminal on it, and plug it into one of the available spare female terminals in the loom? Do I ignore it? Do I do something else with it?
 
FWIW, I had a low beam failure in the not too distant past. The safety relay (or reserve lighting unit) worked just fine. All of the relays on both of the vintage XS bikes I'm driving operate just fine.
 
I think you can ignore it. The switch style you had originally grounded through the handlebar over to the left switch. Your new switch should do the same. Around '82, Yamaha finally gave the right switch it's own dedicated ground wire but previous to that, they all grounded through the bars. The left switch has a ground wire connected to the housing. It transfers that ground into the handlebars when clamped to them. The right switch picks that ground up in the same manner .....

I7OCZNO.jpg


If you're using painted bars, you'll need to clean the paint off the bottom side where these control housing ground clips make contact.
 
Last edited:
jetmechmarty said:
FWIW, I had a low beam failure in the not too distant past. The safety relay (or reserve lighting unit) worked just mine. All of the relays on both of the vintage XS bikes I'm driving operate just fine.
Click to expand...
Same here. Recently disconnected the low beam on the SG. Reserve Lighting Unit kicked in and lit the high beam and the warning light. As long as it still works, I'll leave it installed and functional.
 
5twins said:
I think you can ignore it. The switch style you had originally grounded through the handlebar over to the left switch. Your new switch should do the same. Around '82, Yamaha finally gave the right switch it's own dedicated ground wire but previous to that, they all grounded through the bars. The left switch has a ground wire connected to the housing. It transfers that ground into the handlebars when clamped to them. The right switch picks that ground up in the same manner .....

I7OCZNO.jpg


If you're using painted bars, you'll need to clean the paint off the bottom side where these control housing grond clips make contact.
Click to expand...

Thanks, Twins. I'm using the stock chromed bars, so I should be good there. I'll report back in a bit. Hopefully with an idling motorcycle.
 
giphy.gif



That right there is the first time that bike's run since October, 2020, which was the first time it'd run since TYooL 1987. The weird buzzing/rattling at the end after I rev it up is just all the junk on my stand vibrating.

Clearly, it needs some work. Yes, I hear it sputtering/misfiring. It needs dialed in for sure. That said, all the lights came on as they should (save the headlight, of course) but the turn signals don't work. I think that's a flasher issue because when I flip the switch either way the relay just goes BRRRRRRRRRRRR and clicks a thousand times a minute.
 
Aaaaaaaaaaaaaaaaaand, it doesn't charge. Because of course it doesn't. Guess I know what I'm doing tomorrow. I'm not too heartbroken at the moment, though. It runs like a champ and sounds fantastic, especially after I did the valves again.
 
Okay, this is weird. I was wrong about the bike not charging. It's "charging", in that it's maintaining the battery, but juice doesn't seem to be flowing to it. I have 12.3 at the battery at idle. When I rev it up, voltage goes up to 12.4, then it goes back down to 12.3 at idle again. All I can get out of the charging system so far is 12.4v. I installed new brushes and cleaned the rotor/stator, so that should be good at least.

Now, about the Rick's Electrics reg/rec. When I fired up the bike yesterday for the first time, I got a shower of sparks from the point where the reg/reg was touching the frame rail. I got sparks running and with just the key on, so I pulled the reg/rec off and just sat it on the battery box cover and no more sparks. Later, I got more sparks from something else and came to realize that the positive battery cable was touching the battery box in such a way that it was electrifying the entire battery box (my mistake, poor routing and the metal connector near the battery was touching). All that makes me think that I cooked the reg/rec, but I'm not convinced yet.

I'm tracing wires and testing things as I can throughout the day, then I'll really tear everything apart later after work. I've been going by the charging system troubleshooting guide in the Tech section and my FSM, so at least I have solid info.

PS: What do we like for flasher relays and chains? I need one of each.
 
Last edited:

Similar threads

MaxPete
The Big Sue resto-mod thread
2 3 4
Replies
72
Views
2K
MaxPete
MaxPete
M
1978 XS650 Special Project
15 16 17
Replies
338
Views
14K
Kevin Werner
Kevin Werner
Rhy650
'82 Bar Hopper
Replies
10
Views
1K
X77S
X77S
B
Picked up my first XS650
Replies
9
Views
1K
Mailman
Mailman
M
Leaks and stuck RPM (high) even with clutch in. 83' xs650 Heritage Special
3 4 5
Replies
86
Views
10K
5twins
5twins
Back
Top