New (to me) GS450 - stuck or broken?

[kirkn]

It's been a while since I've posted here (sold my GS700E some months ago), but I just picked up a little '82 GS450T for $350, including title, so I thought I post it up:







It cleaned up pretty nice, and is all complete except for a rear grab rail and mirrors.

But, it had a 'stuck' motor, so I basically took a gamble. All the electrics and whatnot all seem to work OK, once I hooked up a battery.

The previous owner had pulled the plugs and poured in some penetrating oil to try and loosen things up - no success. So, I pulled off the ignition cover on the right side and used a 19mm wrench on the large nut there and lo and behold! the motor wouldn't turn forwards, but would turn backwards nearly 360 degrees, but it "hits" something inside, forwards or back, at that same spot.

So, I peeked in the spark plug holes while doing this, and I see that the left side piston doesn't appear to be moving at all! Yep, I poked a wire down there, and I could push the piston down a bit, but it hits. It was only then that I did some digging and realized the 450s have split connecting rods, which is unlike any motorcycle I've worked on.

So, I'm thinking that somehow, things have separated down there, and the crank is 'hitting' the connecting rod each time around.

Sigh.

I guess I'll be splitting the cases, just to see what's what.

So, that's about all for now. I'll post progress pix as I disassemble.

Kirk

[mike_of_bbg]

That's a nice-looking specimen there - particularly for the price. Was there going to be a question about something being stuck or broken though?

[kirkn]

I hit the "enter" key prematurely. Oops.

No real question, just kind of a 'current situation'. More pix as I go.

Any thoughts on what might be wrong?

[pete]

Mate cosmetically that look like an awesome score! A very neat 450!

It does sound like a case split is in order though...

I was thinking something awry with the cam chain tensioner at first when you said it would rotate backwards, but if the left piston's doing that, I reckon you're right that something down low is amiss...

You know it's possible to slot a GS500 motor in a 450 frame right?

Just a slight tweek to the exhaust is required...

[kirkn]

Well, I had an hour or so this evening, so I managed to get the engine "peripherals" stripped off - exhaust, carbs, sprocket cover, drained the oil... phew, it really smelled STRONG of penetrating oil. I guess the previous owner dumped a lot of it in the spark plug holes and it just found it's way right down to the pan.

Next will come the top end while still in the bike, then we'll see.

Kirk

[pete]

Wow I can't believe how clean she is! Would be a real shame if it was broken and in that sort of condition...

[Mr Rogers]

congratulation on the bike! Mine looks the same just black (i payed a lot more than i should have too...). I'm excited to see how you figure this one out. i'm sure it will help myself and others.

[kirkn]

Baby-stepping right along. Spent 45 minutes or so this morning before leaving for work.

I pulled the cam cover off - the camchain was nice & tight so it seemed to be all OK. Very clean inside, too.





And, got the tensioner and cams out OK. So far, so good. Next will come pulling the head, cylinder and pistons. Then I should know better what's what.

[Bookmon]

Wow! Great Price. Can't wait to hear you have it purring again.
-Bookmon

[kirkn]

Another hour or so disassembling...

Head came off just fine. Looks pretty nice, although dirty on the outside. Plus, a quick pic of my parts-storage routine: labeled ziplock baggies and plastic tubs. And a notebook pad of every step in disass'y so reass'y is just in reverse.









Then, the cylinders came off, and they didn't look too bad either, although dirty on the outside.









But - Uh oh.... that left con rod / crank journal isn't supposed to be visible, I don't think...





Oh, I don't think it's supposed to look like that:










Well, so there we have it. I guess next will be pull the motor and split the cases to see what other damage there might be. But, I slowly turned the crank from the ignition end, and it turned easily and smoothly thru several complete revolutions, so that's a good sign for other stuff - clutch, trans, etc.

Sigh.

Guess I'll have to keep my eye open for used crank / rods / bottom end / ??

Kirk

[spyug]

Jeez Kirk, that is too bad but you may have lucked out on the crank. I shouldn't think it would be too difficult to get a new conrod and bearings etc. The piston looks ok but how is the bore? Any scuffs, gouges? There's going to be a lot of debris in the sump so you should really have it all apart for a proper looky look and cleanup.

I wonder how something like that happens? I don't think I've ever seen a rod go like that without smashing the piston and bending the valves. Wow.

Good luck with it and let us know how it turns out. Great score on the bike none the less.

Cheers,
spyug

[SqDancerLynn1]

From the looks of the rod ? there may be damage to the cases. Find another motor or I have heard you can use the 500 motor but you need to use the 450 head because of the exhaust pipe placement???

Don't even think of using that crank without regrinding it if possible

[Bookmon]

as a neophyte to this whole idea of "I'm going to take a wrench and do what?!"-
Thank you for pictures and tips.
_bookmon
wifey says, "Why can we find bikes like that?"

[Mekanix]

This happened at high engine speed and locked solid by the looks of it.