timing chain R&R?

On my 1981 550 project bike, I can turn the crank about 357°. It stops at the same position in either direction, minus 2° or 3°.

In between the stopping points, it is smoooooth. on clockwise, I hear a noise in the case, like a sprocket or gear. On counterclockwise, there is no sound.
I've had the alternator and starter out. No difference.
I had the tensioner out, and tried to loose the springs and plungers! Like a champagne cork, lucky I didn't aim it at my eyes!
I did try to push the rear chain guide with my fingers, but it seems quite stiff, maybe because of the awkward position. I used a short extension and it did move, but I don't think it stayed in the tensioned direction by the time I got the loaded tensioner back in place.

Wish I had a scope to peer into those cylinders. Even with the carbs off I cant seem to get enough light to look down the plug holes or off a mirror through the intake ports.
I did try blowing some unregulated compressor air into both holes for each cylinder, but nothing seemed to move - like a loose screw or something. (maybe hindered by the bit of ATF oil I put in each cylinder before attempting the rotation. [ATF = lube and detergent since I dont have nay Marvel on hand.])

Since I cant get a full rotation at the crank, I want to lift the cams, which requires undoing the chain. (or does it??) Lifting the cams means I can't be hitting any valves for sure. I am not seeing any valve sticking in the open position. The shims seem to stay very close to the lobes.

Still no manuals, but for the time being, I'm still on disassembly to find the bind.

I see one link accessible that has copper colored pins. Is this the proper master link - or is there one?
And, do you suppose my bicycle tool kit chain break will do the job, or do I need a larger one?
I do know I need to NOT drop parts into the case. With the chain broke, is there enough space below the crank sprocket to lower the secured chain and rotate the crank without interference?

I thought maybe the cams are that badly timed, but I think the motor has been run in the current configuration. - the chain and bridge aren't brand new.

Any other thoughts on a cause for the non-rotation?

side note: When I got the 550 (at the start of May), the carbs were in a box - PO said they were rebuilt, but when they installed them and opened the throttle, the needles were bent by the butterflies.
I cant see that, BUT #1 carb is missing the diaphragm and other upper bits. (which leads me back to maybe something in the hole, blocking the piston!?!?) So, they do look clean, and the screws have seen better days, but I'll open the bowls to see how well they were clean/rebuilt. I have a whole spare set for parts to repair the partial one.

Thanks
Steve

 

So there...
I got the cams out without breaking the chain.

And then the motor still would not turn...

so off came the head...

as soon as I get batteries, Ill get some pics of the screw sitting on top of the piston in #1, and a pic of the screw in #4
Thats right, 2 screws.
2 possibilities: Kids messing around when the carbs were off for the rebuild.
or the PO did it to be malicious for any unknown reason.

Oh yea, neither screw are part of this bike at all.
The motor was never run with either screw in the chamber.
Lucky for me, I decided to make sure this motor wasn't stuck form some long storage.
Now I clean, valve job, order gaskets, reassemble...

Pics to come

Steve

 

Well ...

Lets do C-S-I XJ

I don't know the odds of dropping a screw into the Spark Plug Cavity and having them fall into the spark plug hole.

That one is on one side and the other the opposite side is "Veddy, veddy Hin-der-ezz-ding"

I doubt the children had anything to do with it.

Curious? Most curious indeed!

They aren't aluminum sheet metal screws by chance ... are they?

 

nope, one a wood screw, and the other is like you'd use for small plastic drywall anchors. Like from a normal workshop junk bin.

Ill check them more closely after i get a couple pics. they are still resting comfortably. I will also mount the intake cam and see if they will fit past the valves. The spark plugs were all good and snug when I took them out, I'd have to say pretty close to the same torque.

whoever, however, now it will be fixed before major damage is done.

Steve

 

I could not be calmly typing those findings in a Popular MotorCycle Forum.
I would be otherwise engaged in a sleepless and endless search for the perpetrator.

I would be so steaming hot you would would have to measure my upset-ness in Degree's Kelvin.

I would be nuts.
I wouldn't rest until I returned those bits of hardware to their rightful owner and found a hole or two to put them in.

Until the Mission was accomplished; that would be Job One!

 

yea, well, buyer beware... I bought it as a project.... If I didn't have confidence in myself to be able to accomplish anything I need to do -aside from any machining work I wouldn't have bought it.

Had I bought it running and THEN found this issue, there would be hell to pay.

The kids who were going to buy it just as I handed over money (it was at a swap meet)... they probably would have destroyed the motor trying to crank it up.

Steve

 

see the screws that don't belong inside the motor on any bike.!!!
I did upload a few pics to the gallery today. I hope they are clear enough. The 256KB limit kinda doesn't help.


one more point of interest.
The smaller headed screw wont fit past the valves at full lift.
I tried.
I double checked.
They will only fit via the spark plug holes.
Indeed, the screws were put there maliciously.

Why are people like that? No call to do crap like this.

Steve

 

Amen brother. That took some doing to install those screws. Someone (unknown) put them there for some (unknown) reason. I'm very glad to hear you took your time and didn't rush into turning the engine over! Heaven knows I would have run a compression test first thing before buying the bike! It is possible the P.O. was an idiot or despised by someone else. I'm glad the bike landed in your lap. Poor thing deserves better.

 

heck, they even went all the way to the second side of the bike after putting in one screw, not even just one in each cylinder on one side or the other.

Since I bought at a swap meet, access to compression testing and all that would have been a bit more trouble... Possibly run a leakdown test with a small compressor or tank. Cranking it over for compression gets more involved. I didn't think it had been stored outdoors, but it was dusty. Probably the back of a barn someplace.

The 3 and a half carbs are really clean - haven't cleaned spar parts to complete the 4th carb. Don't know why the bits were missing.

Even if it was a money pit project the PO was sick fixing.
WHY screw the next guy? Your getting some money for the bike and whatever parts. I do know people who would try and track down the PO and do something.
Id rather have it up and running in time for the fall swap and thumb my nose at them, while sitting on the not-dead two wheeler.


I have heard hundreds of stories about people driving a running rustbucket or wrecked car to the junk yard. They sell the car to the yard, then fire it up with a brick on the accelerator. They watch it blowup. Usually very unspectacular. Now the yard has a pile of iron that is less salvageable for parts.
It is like they are getting back at the junk yard for their problems...


www.partsnmore.com shows a 44pc gasket set for a whole $66. I should get my order in asap so I might get some ridding in this summer!

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Steve

 

Sounds like wisdom on the gasket kit Steve but don't forget, those gasket kits don't include the seals. You'll need to source the seals separately. Pain in the butt but Lord knows why they don't sell the set together. Best of luck on your new adventure. Keep us posted on the progress.

 

Of course they leave out bits... that would be too easy!
which seals? valve stem? or mains like crank and output shaft?

I am figuring to clean and lap the valves since the head is off.

One thing I haven't spotted at all: where to get shims and shim tool for valve adjust?
Any ideas on that?


Steve

 

I would definitely replace the valve seals as well. Good time to do it. The other seals would be the main seal for the crank, the output shaft seal, the alternator shaft seal, the shifting shaft seal, and the starter seal (o-ring but who's counting?). Parts-N-More sell seal kits just not for the 650/750. There is an inexpensive valve tool available (about $15) at most bike suppliers. I own one and it works great. You can try the ZipTie wedge method outlined in one of our posters threads, no harm in that and only a few pennies for the "tool". Or you can simply remove the cams to replace the shims. Shims can be purchased at about $5 a piece, aftermarket is fine. Hit the folks at the shim pool on the XJ Owners club. They offer a shim exchange but I don't have their email addy handy.