Somewhat scared and apprehensive

To offer answers to some of your questions, no need to apologise for asking questions, better to ask than break something.

There's nearly always a black coating inside a cam box, I reckon it's precipitate from used engine oil - combustion by-products.

The cam followers look a bit rubbed but I think they are fine as long as not wearing through the hard surface. However, the tappet adjusters look worn. You could clean them up - there's threads on this forum - or consider replacing. It's not expensive to buy some Allen headed ones, which I did and this makes setting the clearances a bit easier.
 
Another alternative for the missing wire clip would be to fab one up and attach it either to the shift shaft guard .....

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..... or face the horizontal leg in and mount it to that engine stud, just like the shift shaft guard mounts.

I find that to be an excellent idea. . the shift guard slides in on a U shaped slot... so with the same U shaped slot .
You can slide in the holder for the cable.. Once something is there .On the other end You can make a Holder for the cable
Pop Rivet a U shape or whatever you like. Half of a pipe Using small screws. Welding
If you dont want to hammer it out on the same metal as on the other end. AS suggested .
One cant make it to thick tough and preferably on the outside of the shift guard so the angle of it remains the same.
Excellent Idea
 
Moving right along with the top end tear down. My hopes of getting away with honing and re-ringing are not very high.

There is some scoring on the right piston and the matching cylinder which looks too deep for a hone.

And boy, looking at the carbon and oil in the combustion chamber and pistons it's a wonder this thing ran as good as it did. Check out the puddled fresh oil on the piston valve recesses.

The cam chain guide looks good. The tensioner shows a little wear but to me looks very serviceable.

Anybody know of a shop or mechanic in my area that can bore and match the rings/pistons to the cylinders? DogBunny, do you have anyone to recommend?

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Interesting.
Rather many miles I suppose
As it seems 2 pistons + rings and a re bore ( At least )
Here where I live a re bore is expensive , It might be a better alternative to buy a kit.
With new parts.
I am no expert so other knows better. But I believe that the cylinder head will clean up
But there are more to inspect -- leakage and play in valves.
Also an evaluation of the con rods..
An experienced mechanic can give an opinion .fex for con rod small end by placing the pin in --and feel.
I have seen specification online for the con rods.
It depends on the plan .. what one wants to do and budget.
But that type of inspection may be well worth it.
It can happen in some cases ... that money and work are spent , and then after not so many miles its time again.
Since it is open ---might as well inspect and measure.
Getting an idea of the grand total cost. before.
 
The way that the outer edges of the piston tops and the outer edge of the combustion chamber around the intake valves are clean and have no carbon stuck there indicates oil was coming in, washing and keeping those areas clean. Probably leaking rings but the way it's clean around the intake valves might indicate bad intake guide seals too.
 
You got that right 5twins, for sure. Fresh oil was everywhere on the pistons. In fact, when you look at the piston rings the compression rings stick out the sides of the piston pretty good. The oil rings are flush with the outside of the pistons. Explains all the smoke.

Went to a hot rod machine shop in S'ville called Steve Sweeney Auto Machine with the cylinder and pistons. Steve measured everything and said one of the pistons was unusable because of the scoring, and it's matching cylinder hole has some scoring also. Long story short, he recommends going to the next size up which would be the .25mm.

So now I need some guidance from the XS650 Guru's. Where should I order to get the pistons and rings. Mike's XS?
Also, I'll need a complete top end gasket kit. I've read that the Vesrah kit is pretty good. I'll need the camshaft seals and valve stem seals also. Where to get those.

Tell me what you would do.
Thanks in advance for your help on this project.

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Yes, what Jim said for the pistons, but I don't think they even sell that 1st oversize (.25), they skip right up to the 2nd (.50). But that's fine. Many times that's what it takes to clean up all the bore scoring. Yes, the Vesrah gasket kit would be good. Many gasket sets include the valve guide seals, and most have any needed o-rings. If the kit doesn't have the guide seals, I would recommend getting some Viton ones off eBay. They're really no more expensive than normal ones.

https://www.ebay.com/itm/YAMAHA-XS6...707615&hash=item3661ef85e6:g:~jAAAOSwgGlepcM1

I don't bother with cam seals unless they're leaking very badly. Many times minor seeping can be cured by thoroughly cleaning the ends of the cam where they ride. Buff them with a Scotchbrite pad. Also, it's something that can be changed out any time with the engine all together if need be.
 
The top end refresh is done!
Cylinders honed to 1st oversize. New pistons, pins and rings. Valves re-ground and lapped in. New valve seals. New Cam seals.

Taken apart and buttoned up exactly as instructed on this forum. After 200 miles so far she is running like new, no smoke, and no leaks anywhere.

Well, runs like new once past idle. I think the low speed needle and/or seat on one of the carbs is not right. And I’m tired of screwing around with the carbs for now.

Thank you XS Gurus for all the tips, instructions, and advice. Some pics.

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Nice job, my first motor was a 71 CB750 when I was 17, some 49 years ago. I remember reading that manual over and over because I couldn't get my head around some of the terms. Plastigage really thru me for a loop. Job well done.
 
Thanks for all your help forum members and xs650 gurus for the info and tutorials. Could not have done this project without your help.

The first 250 break in miles were short trips of no more than 3500rpm just tooling around on some laid back farm to market roads.

Today I took it out for it's first Texas highway ride-a-bout with two buddies, 750 Ducati and 1000 Aprilla. For those that don't know, most of the speed limits on the country roads in Texas are 70mph, which doesn't matter cause nobody pays any attention anyway.

Took it up to a high of 5500rpm and tried to cruise it up and down. Just like how you're supposed to do when breaking in a rebuild.

That dang old machine runs like a scalded dog.

After about 100 miles of hauling butt on Texas back roads, got it back into the barn and checked it for oil leaks. Base gasket, head gasket, cam seals, oil pipes. Not a leak anywhere, nothing.

Thanks guys.

Keep em running.

Cheers,
Mick

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No oil leaks ..... yet, lol. You're going to need to check the head bolt torques a couple of times within the first few thousand miles. It's normal for them to loosen up as the new gaskets compress and settle in.
 
No oil leaks ..... yet, lol. You're going to need to check the head bolt torques a couple of times within the first few thousand miles. It's normal for them to loosen up as the new gaskets compress and settle in.

I second what 5twins said. I've especially learned to retorque head bolts first thing in the Spring after the bikes hibernated for the winter. Though I store the bikes where it is never below freezing, the extended period in cooler temps seems to cause seeping come Spring if I don't retorque.
 
Boy, what a difference an oil makes!

Finally got over 500 break in miles since the top end refresh. Dumped the Rotella dino 15-40. In the sunlight you could see the tiny sparkles of metallic dust. Some metal dust on the magnetic drain plugs. Couple of slivers of metal in the oil filter.

Put in a couple quarts of Amsoil V-Twin 20-50 and took her out for a spin. Noticeable difference right off the bat. The clutch is easier, the trans shifts smoother and the motor runs quieter.

No leaks anywhere.

Funny thing happened though. While kicking the bike with the motor cooled down and no choke, I got a backfire through the right carb. Enough to blow the carb right out of the rubber manifold. Note to self: Be sure to check and tighten the clamps every once in a while.

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Smoke on decel is almost certainly valve guide seals. Although slightly harder than a pushrod engine... it's still a pretty easy top end. If you've done one you can do the other. Have a read through the Top End Buildup thread in Tech. I've never used it, but I've heard tell it's pretty good. :rolleyes:

This is the definitive engine rebuild thread IMO - whatever Jim says, goes.
Pete
 
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