Zero compression XS1100

[Gordo1]

Hello,
I am brand new to the forum. I picked up an 81 XS 1100 with 25,000 kms on it. I got a sweet deal and the usual story that "it ran great before I parked it". I bought it as a project so I was not too worried. I soon found out that it was seized but some diesel fuel and patience solved that. I put in a new battery, changed the oil and plugs and tried to start it with no luck. If I sprayed a little starting fluid into the carbs, it would run. I cleaned the carbs and have fuel in all the float bowls. I also have spark. When I checked the compression cyl 2,3,4 all have 120 psi. Cyl 1 has zero. I turned the engine over by hand and can see that the valves are opening/closing as they should. The piston goes up and down as it should as well. I poured some diesel into the cylinder on top of the piston and it does not leak down (though maybe a cracked ring or hole in the piston/cylinder. (I do not know why the bike was parked) When I shine a light into the plug hole and can see light around the exhaust valve when it should be closed. (not much, but some) My question is - would a slight exhaust valve gap cause zero compression? Also, without the starting fliud the bike does not fire at all. I would expect it to run rough with one bad cylinder but I thought it would start. I also noticed that the vacuum from the intake side of cyl 1 affects the timing (correct me if I am mistaken) Since I have no compression in cyl 1 and therfore no vacuum, would the timing be affected?
This will be a fun bike when I am done and I will stick with this until it is on the road. Can anyone offer some advice?
Gord

[Snow]

Bent valve perhaps? IMHO, it *should* run with 3 cylinders if the carbs are perfect or very good condition (not needing cleaning, etc), but you wouldn't want to run it knowing there is a problem with the top end.

Two obvious options would be:
1. Take the head off, take it to a shop, and have them check it out and fix it. You'll probably spend a couple hundred getting new valves/valvestem seals/and grinding, but it would be worth it in the long run.

2. Buy a complete head off the XS11 classifieds or ebay and hope it works. You'd probably have better luck with a good head from here. Shipping would be expensive though and there are no guarantees with 25+ year old parts.

As long as you have the head off, go ahead and replace the timing chain

I'm sure you'll get more/better replies from the engine gurus shortly, so just hang in there.

[Ken Talbot]

Hey, Gord, welcome from Revelstoke! Always good to hear from another XSive within a short drive of here.

Like Snow says, it sounds like you may have a bent valve, but maybe you'll get lucky and just have a stuck one. Having a bad valve is bad enough, but not knowing what caused it is a bit of a concern. I wouldn't try running it any more until you can take the top end off and sort it out.

You could be looking a few $$ to do a proper valve job by the time you have a machine shop do the seats and valves. I'd suggest going ahead and stripping it down to find out what happenned. Depending on how serious it is, you might be better off checking out the M/C boneyard in Westbank. Last time I was there, he still had a few motors laying around that you could cannibalize for a top end. If that doesn't work out, I might be able to set you up with one of the spares I've got out in my shed.

BTW - have you ever met Yukonman? He (Peter Ledrew) also lives in Westbank and he rides one of the original '78 E models.

[LoserShoes]

Re: Zero compression XS1100

Originally posted by Gordo1
When I shine a light into the plug hole and can see light around the exhaust valve when it should be closed. (not much, but some) My question is - would a slight exhaust valve gap cause zero compression?

You Betcha!
Pull the valve cover off, and with the pointy side of the cam up on that valve, check and see if there is any gap between the cam and the valve lifter. Maybe just needs a different shim.

Also, without the starting fliud the bike does not fire at all.

If it fires with starter fluid, the carbs are most likely plugged, especially the enricher circuits.

Steve

[prometheus578]

"Nothing beats a head job"

Yup... you've got a bent one, there. Or as Losershoes stated, no valve clearance. With the lobe pointed away from the shim, if you have no clearance, then the cam can be holdin' the valve open. If you have a lot more clearance than you're 'sposed to, then you have a bent valve. (I had .035 with my bent one) The flashlight trick, while looking through the exhaust port is a good indicator.
How it got bent is anyone's guess. Valve might have stuck and gotten struck by the piston... or some clown might have honked it up when adjusting the valves, like I think I did once.
If it is bent.... time to pull the head. You might only get away with replacing one valve. With the head off, pour some fuel into the intake and then the exhaust ports and see if it leaks past the valves. I'd say, considering the compression on the other cylinders, that you can get away with just lapping them in again. Replace the valve oil seals, as those things are 25 years old. Snake in a new cam chain also, and you're all set fer summer.
Plenty of advice to be had here. Some of it actually useful!

[prometheus578]

"head job... nipples... where's this thread going?"

Sorry... the vacuum line for the timing should be connected to carb #2... not at the rubber manifold, but to the nipple on the carb, itself. This would not affect starting. Not starting means no fool, you fuel. Again, Losershoes is correct about plugged enrighener circuit. It gets it's fuel from the jet and funnel-like thing in the float bowl. Make sure that that's not plugged. Topcat or Ken has posted many photos of that area. Time to disassemble the carbs and have at it again. No reason to take them offa the bank... just keep them all together and clean them one by one.

[andreashweiss]

I cannot believe you found a bike so close to me and I missed it. I am just south of you in Osoyoos b.c I have a complete xs1100 head off of a 1981 xs1100h model low miles on motor approx 28800 km Can take the head off if you need it. andreas 1250 4953445

[Gordo1]

Thanks, everyone. I have a few new things to try. I checked the clearance and have .021 on the leaky valve and .007 on the others. I have been hoping that it was just sticking but am kinda losing that hope. Now I just need some spare time. It's kinda cool that there are lot's of people on this forum that live close by. Hopefully I'll get to meet some of you this summer. I have "restored" a lot of old bikes over the years but this is my first 4 cyl Yamaha. Looks like I may have a challenge with this one.

[Ken Talbot]

Funny you should mention it, Gord. Check out this post for the initial info on a rally SWMBO and I will be hosting here in Revelstoke in August....

[trbig]

Are you sure of those numbers on clearance? Either you have an extra zero in the measurement, or maybe you used a standard feeler gauge instead of metric?

Here's a cool conversion calculator if anyone needs one:

Conversion Calculator

Tod

[Gordo1]

I was reading the standard measurement. .021" is .533mm. .007" is .18mm. I will be working on it this weekend. I may as well pull the head and maybe see what I am up against. The rest of the bike is in alright shape and I got it cheap so a little investment won't kill me. The rally in Revelstoke sound interesting. I better have it on the road by August Thanks again for all the help. I am sure I will have more questions....
Gord

[trbig]

If you have any problem attaining shims when you get to that point, ask on here. Several people have a pretty good assortment, including myself.

Tod

[Yamaniac]

Originally posted by trbig
If you have any problem attaining shims when you get to that point, ask on here. Several people have a pretty good assortment, including myself.

Tod

Tod,

where is a good place to purchase shims? Does Yamaha still carry them?

Thanks
Theron

[TopCatGr58]

Shim shiminy, shim shiminy, shim shim sheree!

Hey Theron,

Check out this thread on Valve Shims:Valve Shim Thread

Good info on matching the required size from a known MC authority:PROMETHEUS, and a good source link!

I also found one from DO Lee offereing to swap some, he had a decent assortment, but he was also having trouble accessing the FOURM a while back, we think we got him straightened out, but haven't heard from him since!?

[trbig]

Theron,

Just check your local bike shop. Any of them that have been around for any length of time should have some in the back somewhere. Yamaha wasn't the only ones to use these shims. Just be careful you get the correct size. Your bike needs a 29mm shim (Across), but I have read on here that there are 29.5mm shims out there that were used on some Suzukis. They won't work unless you have a milling machine or a really big hammer!! I ended up buying a bunch I didn't need at 5 bucks a piece, but I have heard of some shops just swapping for the ones you have. Just a word to the wise... when installing your cam chain back on, make sure everything is timed like the book says, and get a light to make sure the bottom end of the cam chain is around the crank sprocket. My chain had slid next to the sprocket just rolling on the crank next to it, and I bent half my valves when I cranked it over. Pistons moved.... cams and valves didn't. I learned alot by doing that..I had an extra motor, but it's a lesson I don't care to learn again.


Tod