Update on my 80SG project & Question

[GLoweVA]

I haven't posted in a while, so here's the update.
So, while the kids were visiting this thanksgiving, I got around to measuring the valve clarences and found an odd ball. #3 exhaust was .045 ! (4 times wider than all the others!) I knew I'd have to pull the head off to see what was up.
Fast Forward. Christmas break: Pulled the head off yesterday and as I had it sitting on the bench, I noticed a little light inside the exhuast port on #3. oh-no I moved it around and looked closer. There was a very small gap around the valve and seat allowing light to come thru. Great!
I didn't have a big enough C-clamp and I was running out of daylight.
Today, bot a bigger C-clamp and went ahead and pulled the valve.
I thought I was gonna find some carbon build up on the seat or stem the was preventing the vavle from fully shutting and that would be it.
After about an hour of cleaning and polishing, I slid the valve in and spun it around to see how it'd seat, what I found was the valve was bent. The valve disc wobbled around ever so slightly.
So, I guess I need a new/used valve.

Side note: Has anyone ever noticed that #2 & 3 exhaust pipes have little bung plugs near the bottom where they connect to the 2 into 1 collector? What are they for? Drains? emission taps? Any ideas?
Here's a pic:

[XS1100_OEM4ME]

Valves

Yea, sounds like you will need at least one of these:
http://www.ebay.com/itm/80-YAMAHA-XS...sories&vxp=mtr
If one is warped (from over heating is the norm) I would take a very close look at the rest of the valves If something happened to warp one, all arew suspect IMHO.
As to the bolts on the exaust down tubes, they only had them on some models, may have been for factory tune and emisions? Nothing in the manuals for serviceing the bikes

[GLoweVA]

Thanks for the link OEM, I'm already watching that on Ebay, plus another one. I've got a PM sent to Andreas to se if he's got one lying around.
Maybe someone here will read this post and offer up a used one.

The valve clearances and the thumb over the hole compression check worked great for the other three cylinders, so I think those are good, plus I didn't see any light shine thru on the others like I did with #3.

It wasn't really 'bent' but was off just enough to not seat perfectly. Maybe I'll try to take a cell phone video of the wobble while I spin it so all can see how just a little is enough to mess up your day.

[XS1100_OEM4ME]

Guild

You may want / need to replace that guild also. If it ran like that it will most likely be worn inside, seen them on Ebay new and other places but i know you can find one

[b.walker5]

Guild ??? Whats a guild ?? Sure you dont mean a Guide..

[GLoweVA]

The stem of the valve is true, so I don't think the guide is worn.
The disc is what wobbled. I rolled the stem on a flat surface and it rolled fine. Like a pool cue on the table.

As for running like that, I can't answer that. This is my project that I picked up about 5 months ago and I haven't got it to run it yet.

[XS1100_OEM4ME]

dyslexia

As I have said before, I have dyslexia, do the best I can considering, hope you don't make fun of kids in wheelchairs also

Guild ??? Whats a guild ?? Sure you dont mean a Guide..

[crazy steve]

..Has anyone ever noticed that #2 & 3 exhaust pipes have little bung plugs near the bottom where they connect to the 2 into 1 collector? What are they for? Drains? emission taps? Any ideas?

Those are wells for EGT (exhaust gas temp) probes so the factory could adjust, and then seal the carbs. You should have these on all four head pipes if the exhaust is original, but a PO probably swapped on pre-80 outer pipes/mufflers...

[XS1100_OEM4ME]

2 &3

Mine is OEM and only on 2 &3 also

Those are wells for EGT (exhaust gas temp) probes so the factory could adjust, and then seal the carbs. You should have these on all four head pipes if the exhaust is original, but a PO probably swapped on pre-80 outer pipes/mufflers...

[bikerphil]

New Vesrah exhaust valves, $25 a pop....

http://www.newmotorcycleparts.com/mo...ts/valves.html

[81xsproject]

Interesting that they only sell the intake for the early 11's, but no exhaust.

[bikerphil]

Interesting that they only sell the intake for the early 11's, but no exhaust.

For the longest time they were out of stock for both the exhaust and intake valves for the 78-79 engines. Yes, it is strange that they only have the intake. Probably left over intakes and both valves being discontinued by Vesrah. Kinda sucks as the #3 exhaust valve is usually the first one to bend when the cam chain is installed improperly falling off the crank sprocket.

[ViperRon]

Valves

I have seen that type of bend in valves before. The first time was when I went to help a friend reinstall the head when he got it back from the shop. Being egar he set the head on the cylinder with the entire thing assembled not sure if he bumped it or dropped it or rotated the engine with the assembled head on it but a valve head had wobble. You probably already have heard this or read it but when you install or remove the head you do it with cam shafts out. You also need to pre-position the engine so that No.1 cylinder piston is TDC. When putting in the cams pre-position them with the dot on the cam alligned with the arrow on the center bearing caps before installing the first bearing cap. It is easy to not do this and bend a valve when installing.

I am not questioning your ability in any way just have seen people get into a rush and make mistakes. If a cam is bolted down with it or the engine out of position there is not much room and a valve will bend before it pushes the piston down. If you have any questions ask here and I am sure more then one will lead you threw it. The only bad question is the one asked after you have a problem.

[GLoweVA]

I don't think that this head has ever been off before, but the possibility does exist that the timing might have been off before and thus #3 got it.
When I got it, I did check the timing marks and they were dead on.
Thanks for all the input.
Those Vesrah valves are replicated parts to OEM specs. Any opinions?
I looked and on my 81SG there are exhuast bungs on all 4 pipes. I guess I've got original OEM Pipes then!

Until I get a replacement Valve, my project is pretty much dead in the water.

[mack]

Valves

It's been awhile since I was into an early head but If I remember correctly, the intake and exhausts valves were the same size.