Hello from Vancouver Island! Newbie with an XS360C

Hello everyone,

My wife and I just recently bought a '76 XS360.
It is my first motorcycle but she has some experience on two wheels.

It needs some work:


The previous owner seemed to think glue and silicone would be a good way to keep it running. The rear turn indicator was held on with a combination of the two.
The head broke off one of the screws holding the cap on the master brake cylinder... so a thick layer of silicone was applied to stop evaporation. It didn't work. The cylinder is dry and encrusted with brake fluid residue.

The engine actually seems all right but should be torn apart and cleaned.

Most obvious repairs:
Replace broken center stand to facilitate further work.
Remove gas tank rust, protect, and paint.
Fix the master brake cylinder. I'd rather not use an aftermarket replacement.
Fix the broken turn indicator.
De-rust the mufflers inside an out.

That's why I'm here. I have already read a lot of good information on this forum and might need some advice along the way.
We are initially looking to get it working, then we'll work on cosmetics. I'd like to use stock parts as much as possible.

Welcome! Nice looking bike. I love the tank and seat Pan of the early models.

Welcome, I've got the same bike but a different colour, that I'm restoring. I see lots of available parts on eBay and my local Yamaha dealer can still get a surprising amount of parts that I need.

I'm anxious to see how you go with your bike.

Welcome to the forum

Without a proper garage I haven't had many chances to work on the bike but I did pull off the master cylinder and front caliper.

Good news so far: the master brake cylinder can be restored. Tore the whole thing apart and removed the broken screw. I'll buy a rebuild kit but it's good to know that the stock cylinder can be used.

Bad news: the brake caliper piston is rusted and stuck inside the caliper. It's been soaking in brake fluid but won't budge. Might soak it in Evapo-rust tomorrow, though the rust might be protected by the brake fluid....
I don't have a compressor or grease gun, two methods I've come across to push the piston out. Next best bet to assemble the whole brake system and pump the handle?

Oh, and the previous owner jury rigged pretty hefty aftermarket turn indicators. Looks like the extra weight tore apart the mounting grommet.
They do work though so until the other priorities are taken care of I'll leave it as-is or somehow remount it.

Ouch, that caliper does look kinda ugly. Evapo-Rust may be your friend there.

Once you deal with that rust maybe you could stop by a service station and use their compressor to try popping it out. I'm not sure if the caliper is worth saving or not. Someone here should know.

The master cyclinder looks nice and clean.

Good luck.

Evapo-rust gets a big thumbs up!
Didn't expect that piston to be usable so I worked out with pliers.
The piston is garbage but I think the caliper should be OK. Just a bit of inside surface roughness visible in the picture.
A rebuild kit for the caliper and cylinder will have the front brakes in top shape.
Rear brakes seem OK.

Next up will be derusting the gas tank. I gather it will be a good idea to coat the inside. Caswell's epoxy is looking pretty good.

Did you find a source for a new caliper piston? Parts N More lists them but has been out of stock since I've been looking.

My first step for my gas tank was the coin car wash. I was able to get most of the rust blown out with a cycle of soap and then a good rinse. Swishing around a piece of chain inside the tank dislodged the rest of the chunky rust. EvapoRust did the rest easily. I don't plan to coat it now.

How is your gas cap seal?

The gas cap seal is in pretty bad shape. Definitely needs to replaced. MikesXS/XS650direct.com has seals but I'm thinking with the rivet issue that I'll need a whole new cap.

Getting the piston from xs650direct as well. It only mentions the 650 but the same item on MikesXS lists the dimensions and they match the old one. Somebody on here said it worked in their xs400 as well.
Cheaper than partsnmore too.

Great to know. Thanks

I bought a new cap from Parts N More. It fits but the quality of the chrome is not as heavy as the stock one. The lock is easily switched.

That got me curious. The chrome on the old cap is in great shape. A quick bit of dremel work and the seal was off:




New seals are only $7.50 on XS650direct. Tiny rivets or machine screws should keep it together.

Make it work

Yeah, good one.

I needed the whole gas cap for my extra tank.

Not too bad for rattlecans:

Not quite running yet.

Haven't tried kicking it yet. Stumbling through troubleshooting the electronics first:
-New rear turn signals need new connectors.
-Turn signals turn on but don't flash, yesterday. Today they don't even turn on...
-Start button does not do anything.
-Horn doesn't work.

There seem to be too many blue wires in the headlight bucket:
-A male and female blue/black which I believe just connect together.
-A much lighter blue/black which has a female and a male connector spliced on.
-A plain blue wire, with a male bullet connector, which doesn't seem to have anything corresponding to plug into. Diagram seems to indicate that it should have a corresponding female connector.

Still trying to get it going. No luck. Just the occasional put-put and after turning it over a lot some oil vapour out of the air filters.

The oil vapour doesn't come out right away, being cold, but after trying the starter for a while it comes out in a big WHOOSH and then seems to die down again.
Is the big whoosh normal or would this indicate something is blocking the crankcase breather?

Compression is low at 110 left, 120 right. A wet test gets both to 150.

Tried the choke both ways. Adjusted the idle screws and played with the throttle a bunch. Double-checked the timing. Sparks seem good, if slightly weaker on the left side.
Tried float heights at the lower end, 24.5mm, and the higher end, 27mm. Seems to not work as much either way.
Valve clearance was set to the looser end of the specified range.
The best I can get it to is the put-put.


Hoped it'd still start even with the low compression.
I think I've exhausted every option except honing cylinders, replacing piston rings, & lapping the valves.

Does anyone have any suggestions before I pull the motor out and pay someone to hone the cylinders?

What is the procedure when dealing with the low compression?
The wet test got the compression to 150. My understanding is this means the valves are sealing correctly? Should I have them lapped anyways since the head will be off?

The cylinders did not appear to have any damage when I last took the head off.
There was a VERY fine amount of surface rust but it wiped off with a cloth.
Checked piston ring/cylinder wall clearances with a feeler gauge and they seemed to be within spec, but probably just barely.

Would just a light honing work?
Do the rings have to be replaced no matter what?
If that's the came I'm looking at getting .25 oversized rings as the std ones aren't available.
I'm not quite clear here. Do I also need to get .25 oversized pistons like Norman1950 did for his 360 or was there something else going on there?

All advice appreciated as I'm at my wit's end.

Hi BBS.
I bought an after market made in Taiwan front brake master cylinder for my XS11 Yamaha. Works great. You will probably have to pump out the caliper. Most other methods might damage the old one. But it may be rusty anyway.
With 150 pounds of pressure I would run the engine. You have too many other things to fix at this stage. I have not even checked the pressure on my 400.
Jim at Victoria Motorcycle 250 383-1912 is a good guy and knows his after market stuff. He also has a salvage yard. I have bought stuff from both places including my 400, and the spare motor.
All the brakes on my XS11 had problems as you describe.

Unkle Crusty

I've been to the scrap yard. Very cool place. Bought some pieces for my stock brake master cylinder, which is now working perfectly. Also got a front brake light switch and headlight bucket.
Decent prices considering everything is in pretty used condition.

The 150 psi is only when doing the wet compression test. When running the engine it goes back down to 110/120.

Everything else has been fixed except a few minor electrical things like hooking up the new turn signals. Waiting for a ratcheting crimper to arrive in the mail to do the stock 3.9mm bullet connectors.

Looks like it's time for a set of pistons and rings. It is always a good idea the lap the valves and replace as much in there while it's apart.

An update and new issue.

The bike is running but the right cylinder isn't firing much.

Decided to tear it down and take the engine out of the frame. When draining the oil I noticed flecks of metal.

Once the valve cover came off I found the problem right away. One of the two bolts holding the camshaft sprocket on had worked its way all the way out, shaving metal off the head until the bolt popped out entirely.

Found what I'm hoping is most of the metal resting on top of the chain tensioner blade. I put it alongside the slightly deformed bolt for the photo.


Looks like I'll be tearing down most of the motor to check for more metal shavings.
Will have to check out the valve seats and piston rings.

Would it be beneficial to lightly hone the cylinders, break the glaze, and refresh the crosshatch pattern, without replacing the piston rings?

Obviously new piston rings would be ideal but they are scarce and expensive.

EDIT: Got the jugs off. The cylinders aren't nearly as worn as I expected. Cross-hatch pattern clearly visible around most of the cylinder walls except in a vertical stripe at the front and back of each cylinder.
Will check cylinder/piston clearance and ring end-gaps tomorrow.