It's past time to start XS2 Resurrection

Damn auto correct.... staking... not stalking. Edited above.
 
After thinking it over, the Lycomings had plenty of valve to piston clearance. The XS... not so much. Might not be such a good idea on our motors. Don't want to smack the valve into the piston. :yikes:
 
Lycoming has a procedure they call "staking the valve." ...

Used to do something like that for the kids that didn't have any money. Little Honda 50cc and 70cc. Open valve lash to about 0.050", rev the hell outta it, belching smoke and dust. Reset valve lash, cheep/easy/instant top-end overhaul...
 
Lycoming has a procedure they call "staking the valve." for carbon buildup. Bring it to TDC, put 80 pounds of air in it, lay a piece of wood on the tip of the valve stem and smack hell out of it about a half dozen times. I've cleaned up many a carboned exhaust valve "staking" it.
Nice thing about the XS650 engine design is with the exhaust valves easy to access at the front all you would need to do is remove the two covers and smack the top of the rocker arm. Trick on any engine is getting it right on TDC so engine won't turn from the pressure on piston.

Never checked but is there a point at the bottom of power stroke where both valves are closed, guess you could just back off the valve adjustments to have them both closed at the bottom of the stroke. Having a full cylinder of air at 80 psi would sure create a good breeze to blow loosen carbon out!

This would also address the lack of piston to valve clearance at TDC.
 
No need for air in the cylinder. Back the pistons down so the valve won't hit one, remove the adjuster screw from the rocker arm, pound on the valve stem top with a drift pin through the screw hole in the rocker. Basically, what you're doing is bouncing the valve open and closed. That can dislodge carbon on the seat and/or clean the stem off where it goes into the guide.
 
Not the worst day I've ever had but not the best. Tore down engine this morning. Went pretty well. Took head, cylinder and piston to machine shop. Cory checked things over for me while I was there. The reason for no compression is a bent exhaust valve. Not much taper to the cylinders, some though. Then the rest of the bad news. One piston/cylinder a little under 3 thousands, the other almost 4. Rats. Not going to put it back together with one cylinder almost at limit. Was hoping to fix head, new rings and a hone. Oh well. Came home and started spending money. Not going to take a chance with getting standard pistons withe the bore showing tapper. Got new 2nd over pistons coming from Cruzinimage, gasket set on its way from Amazon. Plus some tools. I've got a spare head from a junker engine I bought a while back. Ordered valve spring compressor so I can see what the exhaust valves look like. Not holding out a lot of hope for them.
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Junker head
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Wish the motor could talk. Piston did not show any marks from the valve kissing it. Oh well it is what it is. Tomorrow have to order the rest of the parts I'm going to need.
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If I have to buy a exhaust valve I was looking at this one on EBay.
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But I'm not sure it's the right one because Partzilla shows the part number as
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Anyone know if they are the same? Or does anyone know a better valve to buy?
 
There was a change to the valves, to the shape of the keeper and the groove in the valve stem it fits into. Early valves (like yours) up to '73 used a keeper with a squared off retainer ring on it, and a corresponding square cut notch in the valve stem. Later valves changed to rounded keepers and notches in the valves .....

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That valve on eBay is most likely the squared off type and is what you'd need if your bent one is too. The style of valves in your parts head would depend on what year it is. The later "rounded" valves are a direct fit replacement for the early ones, as long as you use the proper "rounded" keepers with them. Here's a later valve with the rounded groove in the stem. You can clearly see the "half moon" profile it's got .....

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..... and here's a later "rounded" keeper .....

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I found some info on EBay when I was trying to verify that info for you. Maybe this will help?
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It’s too bad this couldn’t be some simple fix for you, but I will enjoy following along with your work! :)
 
Thank you 5twins.
My parts head is from a 73 so if one of the exhaust valves is usable I should be OK. I remember reading about the change. What confused me was Partzilla. I guess they are showing the updated part number, not the original part number. I do know what to look for now.
 
:popcorn:

I am not enjoying your difficulties GLJ, but am certainly enjoying this whole discussion.

Pete
 
:popcorn:

I am not enjoying your difficulties GLJ, but am certainly enjoying this whole discussion.

Pete
Not really difficulties. Just part of working on engines. When I bought the parts bike I knew I was buying a pig in the poke. I guess the pig is poking me. This is the first time I've rebuilt a engine since 1992. Kind of fun. Last engine was a 454 in a Camaro.
 
At least the XS650 is a bit easier to lift up on the work bench by one's self!
650 was more work. had to muscle it out of the frame and the 6 inches onto the lift. With the 454 I had a full shop. Cherry picker, engine stand. You did not try to muscle a big block. Or small block for that matter.
 
Has anybody used this seal kit? If so what did you think of them. It's also on EBay a few buck cheaper. Same seller.
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Or there is this one.
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A coupla concerns not easily discernible.
- Actual photo, or a stock pic?
- Brand, the ARS is probably all ARS, but the others?
- Retention ring? Hoop, barb, smooth-sided?
- 40-year-old stock, or new?
- Thickness dimensions of the camshaft seals, 5mm or 6mm or 7mm?
- Single lip, dual lip, single with dust shield?

A worthwhile read:

http://www.xs650.com/threads/engine-oil-seals.52383/
 
New exhaust valve showed up today. It's made for square keepers so I should be good there. The package had never been opened.
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Doing some cleaning on engine and noticed blue goo where there shouldn't be.
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Guess that's one way to fix a leaking seal. I ordered the SKF seal kit Friday. Be interesting to see what they are and what they look like. Checked on pistons. Tracking shows they are in Chicago. Could get them any day next week. Think while I've got time I'll pull clutch apart and see what it looks like plus other odds and ends. Still need to order cam chain, front guide and cam seals.
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