Topic: Had it running, but it all turned out so wrong...

[DammitDan]

I've been working on my '82 CB650 STD for about 8 months now since I drove it into a ditch (a long and painful story involving inexperience, stupidity, and a 5 hour hospital stay strapped to a spine board), and finally got the thing put back together.  Mind you, this is after doing some of the dumbest things you've ever seen, such as warping the head, dropping several ferrous and non-ferrous materials into the crankcase on different occasions, and having to install helicoils in every one of the head bolt holes (I can only assume the original owner tried to "fix" a head gasket leak by overtorquing the head bolts ). 

So anyways, back to what's wrong, of which there are several things.  First, I had it running for about 10 seconds before I found I had backpressure on the carbs.  Adjusted the valves (by the way, Clymer listed exhaust and intake adjustments backwards for #2 and #3 when adjusting TDC on #1) and it mostly went away, but there's still a bit of backpressure on #1... now it just lightly chugs instead of hard puffs.  Should there be any at all, and how should I fix it?

Second, #2 and #3 run VERY HOT compared to #1 and #4, which are just warm after a few minutes of idle. This could be a carb problem, ignition timing problem, or valve problem from what I can tell.  Also, #2 and #3 spark plugs come out very black while 1 and 4 are almost clean, with a little darkening.  Does this make 2 and 3 run hot because they're running too rich and 1 and 4 cool because they're lean?

Finally, the biggest problem.  I got it out to ride around the local school parking lot for the first time in 8 months... and it felt great, until the motor died.  Now, I was used to this happening, since the motor refused to idle without choke, and continually died when I pulled in the clutch while riding.  This once again leads me to think the carbs need cleaning, which I have yet to do.  However, the last time it died, it also refused to start and acted like it was seized up.  Had to walk a mile back to the house (never fun in 90 degree weather) and get the bike back home via trailer... tore down the engine and found that the cam shaft had an arm sheared off.  Both bolts were pinned against the head by the sprocket (a miracle they hadn't fallen down, unlike the sheared off arm), which had come off of its' position on the shaft, I assume locking up the engine.

Good news is, after breaking down the engine to the crankcase again, I fished out the broken arm with a magnet, and the engine still turns over fine.  Bad news is, the head is scored in a circle by the bolts that came out off of the cam shaft/sprocket, and now there are aluminum shavings down inside the crankcase.  Oh yeah, and I have to find a new cam shaft and sprocket.  Do you guys recommend getting a new head, too, since it's (lightly) scored?  And how should I go about getting the aluminum shavings out?

Phew!  I've been dying to vent this story somewhere, and none of my co-workers wanna hear about it.  Bah! 

Thanks,
 - Dan-0
 - dah2x@mtsu.edu

[SteveD CB500F]

Aluminium shavings in the engine are bad news.

The 500 (shown left) broke its camchain tensioner and shaved aluminium off the inside of the cam tunnel until the shavings had:
a) blocked the oil filter
b) caused the bypass valve to operate
c) ended up in every bearing in the engine

My only defense is that this was nearly 30 years ago and I was young (and stupid)

A complete engine rebuild with new shells fixed it and it went on for many years.

If your shavings are large they may just be in the sump, in which case, drain the oil and remove the sump plate. (I am assuming here that the 650 is basically the same as the 500/550)

[DammitDan]

So there's no way to "flush out" the engine without opening the bottom end?

 - Dan-0
 - dah2x@mtsu.edu

[SteveD CB500F]

Try it.  Drain the oil, open it up and have a look in there!

[Lumbee]

..if its like the 750's, you can remove the oil pan on the bottom of the engine and see what you find.  Beyond that dude...damn...thats quite a story on this bike.  Unless theres some sentimental attachment I say use this baby for parts and find u another for a few hundred bucks...

[DammitDan]

..if its like the 750's, you can remove the oil pan on the bottom of the engine and see what you find. Beyond that dude...damn...thats quite a story on this bike. Unless theres some sentimental attachment I say use this baby for parts and find u another for a few hundred bucks...

The pan on the cb650 is easily removable, but I haven't had the chance to do this yet...  I guess it will be the first step in the next stage of repair.  The stage where I finally remove the engine from the frame.

Honestly, I don't know what my attachment to this bike is.  I'm stubborn.  I refuse to accept that this bike won't get started again.  And considering the beast tried to kill me once, I feel obliged to break her into submission by tearing her down and building her new.  I WILL get the bike back together, and I WILL get it purring like a kitten.  Then I'll sell it for a loss (already spent WAY more on it than I can get out of it) and start on something new... Those Yamaha Midnight 850 Specials sure look sharp... 

 - Dan-0
 - dah2x@mtsu.edu

[DammitDan]

Alright, a quick update.

I drained the oil, and it didn't look too bad, then I took off the filter and dumped it... you know that sparkle paint stuff you can buy for your kids?  Yeah, that's what this oil looked like.  Tiny tiny speckles of aluminum.  Since the oil I drained looked pretty clean, I guess that means the filter took the brunt of the attack.

I then took 2 1/2 hours to wrestle the engine out of the frame, and pulled the pan on it (I know I didn't have to pull the engine for that, but I'm gonna break it all the way down anyways)...  The pan is where I found the BIG shavings.  So that means my strainer was doing its' job correctly.

Next step:  Break open the crankcase.  I expect to find some nice shiney presents inside.  Maybe I'll use them to spackle the gas tank... It'll be llike a badge of honor 

Any tips or suggestions on what to look or watch out for? 

Thank'ee 

[oldbiker]

Wouldn't it be better and easier to get a second hand motor in running condition, put it in your bike so that you can take your time over reconditioning the original motor. That way you won't lose much riding time.

[Uncle Ernie]

Dammitdan! You sure picked the right moniker. I'd try one of the new aluminium electro-magnets. If you wire 4 together in series, wrap them around the engine, plug it in and run the engine for 5 minutes... sorry. Couldn't  finish.
Melt that head down. Maybe invent aluminium musket balls or something. Depending on miles, you'll probably want to get new bottom-end bearings, too.
By the way, in all the old machines I've run, a richer mixture will help keep things running a little cooler. I suspect #s 2 & 3 just naturally run a bit hotter because of less accessability to wind (unless you're talking about being close to meltdown).
I'm leaning in the direction of oldbiker's advice. I've had a transplant, and I don't think my wife and dog love me any less...