Valve seats disassembly pics (XS1B)

[richard]

Here are a few pics of the valve job I stared today on my XS1B. I am still waiting on valve stem seals but I thought I would see how far I could get. The valve and seats were all pitted so I suspect that none of them were sealing very well. That would account for my low compression.

I bought I had a C-Type valve compressor but it didn’t seem to be large enough so I decided to make a spring compressor from a 9 inch C clamp. I just ground the stationary end down flat and the drilled it out with a 5/8 drill bit. It worked pretty well and the valve keepers were easy to get out. I will say though that the keepers were on the exhaust valves pretty tight and snapped as they came lose.



This is how the end the looks as I removed one set of keepers. I was very careful to keep the screw end of the clamp dead center on the valve just in case. I didn’t want to deflect the neck of the valve at all which would ruin it. They are pretty hard but it always helps if your careful when forcing something.



Before I started this project I made a organizer for the valves and springs out of some left over 1 X 12 I had around. Then a just drilled some holes into it to hold the valve stems. Next I inserted some dowels into the holes to set the spring on. The nice thing about this is since it is just going to be discard when you’re done so you can write all over it to keep track of things. I used to use a 2X4 made up like this for V8 heads before I had the money to just send them off.



This is the valves as I stuck in the block. You can see the notes I wrote with a felt pen so I could remeber where they go.



This is the intake valve which appeared to be leaking the worst. It has some wear that concerned me but I’ll just have to see if it will lap and if it doesn’t I'll replace it.

(I decided to have a machine shop look at the valve and figured out that it is bent so I'll have to replace it. When got the bike it ran but the timing was way advance. I kind of suspected it might have jumped time. The pistons don't show any signs of a strike but I am replacing them anyway. I guess I'm lucky this wasn't much worse and now I'm glad I decided to replace the cam chain before riding it very much. This bike had a slight clicking sound from the start I figured it was the master link on the timing chain passing over vain between the cylinders but now it occurs to me in might have been the valve contacting the piston.)



This it the seat it came out ot which is very pitted. the others were pitted but not as bad.



This is the port as I started to clean it up



and this it the two valve seats on the one side pitted as can be.


I have three grades of grinding compound it will be interesting to see if I can lap those pits out. I'm kind of wondering at this point if I shouldn’t just have them ground. It will depend on how much progress I make with the course grade compound. There is plenty of seat left there which for me was a relief and the valve didn’t look too bad.

Well that’s it for now I’ll post more later when I get the chance.

I hope you enjoyed the post.

Richard

[XS Rod]

I would grind them but I am definitely always on the overkill side... it's not done till it's overdone. I would regrind the seats and valves to make sure they are all concentric.
I replaced the valves in mine as the stems were pitted. replaced them with S/S ones from 650 Central with my old S&W Valve springs and retainers. The seats were fresh so I just lapped them in and did the liquid leak test. The head they went in was ported by the Master himself Shell. Spigots are matched to the head and ceramic coated... see what I mean?
The little board you made is cool... we could definitely hang out bro.
How was your valve spring compressor? Mine had issues even though I tried modifying it. Had to play with it to clear the upper head casting.

[5twins]

What you'll need to keep an eye on is the seat width. As you lap the valves in, this may get wider. There are specs for it in the manual. They need to be the proper width for sealing and heat transfer purposes. I just checked mine before and after lapping with a 6" rule. Not an exact way of measuring but it was good enough for me to determine if the seats were still within the spec. If they end up too wide, you'll need to have them cut.

These heads use what's called a 3 angle cut. To narrow the seat back down, the 2 approach angles on either side of it will need to be cut.



On the porting, you'll want to leave the exhausts nice and smooth but rough the intakes back up with a sanding roll after smoothing out all the lumps and bumps. If the intake is too polished, the gas droplets can drop out of suspension as the fuel/air mix passes through the port.

[richard]

The C-clamp worked pretty good. I did have to move it around a little to keep from running onto the head. But it would compress enough to get the keepers off in any position. That block to hold the valve is kind of neat but I weird that way.

I was looking at the valves and seats this morning and I’m pretty sure at least one valve needs to be ground so might as well do them all while you have it there. Thinking I can lap that wear out is probably wishful thinking. I am going to see if I can find someone to do the grinding because I don’t do this kind of stuff often enough to warrant buying the grinding tools. I am of the opinion that the biggest part of my compression problems was those valves leaking.

I don't know about the valve springs. None of them were broken and they looked ok to me but I have no way to measure tension so I thought I would reuse them it there was nothing wrong with them

What has me puzzled me is it they held fluid before I took them apart. I can’t figure out how they could because they look bad.

[5twins]

Did you test with compressed air or just fill the combustion chambers with liquid and wait to see if any leaked by? The liquid leak test isn't as good as using compressed air. It will only show the really big leaks, not all the little ones.

Intake ports usually stay pretty clean. They're constantly being washed by the fuel/air mix passing through them. The deposits on the back of your valve and the blackened area around the seat do seem to indicate that valve was leaking compressed gases back into the port.

[richard]

I just filled the combustion chambers wit fluid and let them set.

I just returned from the machine shop. They said all the valve are usable. The stems and guides are fine so it is just a matter of cutting the seats and grinding the valve a little. The one valve would has to be ground more but they said if that was the case they would shim the springs to match. The guy said it would be not more $150 The cost was mostly because of the time. They wanted to put it back together. I cleaned it up pretty good so I guess that will be ok.

I remember when you could get a V8 head done for $75 bucks.

[richard]

I am really concerned that my pistons new pistons might be too tight the book says. “ If it is possible to insert a .004 feeler gauge between the piston and the cylinder wall on the thrust side, remedial action must be taken” So mine is within spec because .003 will fit but .004 won’t it’s just .003 means .0015 per side on center and that seems really tight to me. Spooky tight. Oil has to get in between the piston and the cylinder wall somehow. that's not much room?

[650leo]

Very clever on rebuilding a c-clamp like that.
The clearance spec is .0020-.0022. With .0039 max. If you can get a .003 between the piston skirt and bore, it is more than called for. You might want to measure the bore and pistons then subtract the piston from the bore to get your clearance.
I have found using a feeler gauge to measure that way to be misleading. As the gauge bends around the curve the width will make it tighter. The blade is trying to measure at both edges. A wire type gauge would be more accurate. The wire takes very little space.

[richard]

I did measure it with a telescoping gauge and caliper and pretty much got the same thing. That .0020-.0022. spec. seems really tight to me fo an air cooled machine. It seems like the heat should cause the piston to expand a little.

Well I have to replace a valve and the the seats cut so when I have that done I'll get a second opinion from the machine shop for the piston clearence at the same time. I'm more worried about them bing too tight than lose.

I never could heear any slap on the original pistons and these at tighter than they were.

[650leo]

Sounds good then.
It will expand some. I think the clearance allows for that. It seems to work.

[richard]

One of my friends that builds bikes was telling me that the Japanese bikes built back then had harder pistons than they do these days so they didn’t expand as much. Anyway the spec is what it is and has been working for 39 years. That’s good enough for me.

[grizld1]

It should be. Older Japanese engines don't typically run tighter specs than newer ones, and piston hardness has little to do with it. OEM and OEM replacement pistons are cast, and expand less than forged performance pistons; .002" clearance is pretty typical. You'd only set up wider if you were running forged pistons: JE, Venolia and Wiseco all recommend .003".

Yamaha recommends piston replacement and bore job if clearance measures .004" or more.

[richard]

Well that makes me feel better.
The last thing I worked on was the 911 and it had forged pistons. Come to think of it my old Chevelle had forged pistons too.