Topic: Alright, I figured out why it seized.

[Carver]

  So how bad do you think my bottom end is mangled? and also I couldn't pop the piston out today but why would it be doing this? rod small end stretched out?

VIDEO0005

[LesterPiglet]

Am I seeing that right? Apart from the obvious piston damage, the bore looks much bigger than the piston and out of round.

[Bailgang]

Am I seeing that right? Apart from the obvious piston damage, the bore looks much bigger than the piston and out of round.

The vid is with the jugs already removed, that bore you're seeing is the block itself where the sleeves sticking out on the bottom of the jugs go in and align.

[MoMo]

Looks bad.  Why did you start another thread rather than continue the other?...Larry

[Carver]

Am I seeing that right? Apart from the obvious piston damage, the bore looks much bigger than the piston and out of round.

The vid is with the jugs already removed, that bore you're seeing is the block itself where the sleeves sticking out on the bottom of the jugs go in and align.

yep yep, a piece of the sleeve fell in to my cases  It was popping out of second gear anyways so i guess i'll fix that and bump this up to 836. I'm just trying to figure out HOW the sleeve broke? Maybe the piston went first and since it had so much "mobility" it smacked the sleeve and seized it while i was riding?

[LesterPiglet]

I must go to bed earlier.   

[martin99]

Maybe it was mishandled by a PO in a previous install. Cracked the sleeve and didn't notice. Over time vibration has done it's worst. The piston should lift up if the crank turns. Maybe a clue as to where the missing piece is?

[bryanj]

If the crank ain't turning when you pull that piston you got a totaled crank and rod mate

[Carver]

I wanna be mad that the majority of my engine is wrecked and i'm unemployed and can't fix it but all i can do is sit back an laugh at how comically the whole engine failed.

[Carver]

If the crank ain't turning when you pull that piston you got a totaled crank and rod mate

yep, the piston just moves up and down on the rod, no crank movement at all.

If I had to guess why the crank isn't moving it would be because a piece of my bore is lodged down there.

[calj737]

Carver - good on you for having a laugh at your engines condition. It could have been far worse, seizing up whilst riding at high speed and them throwing your arse over tea kettle into traffic. Then, the meaning of being "lodged" would take on a whole new perspective.

Delighted you are well, condolences for your motor!

[iron_worker]

I would bet that the rod bearing seized/spun which by now obviously the rod bearing, rod journal, and crank journal are now all obviously completely munched. Once that happened it allowed the rod to slap around enough to smack the bottom of the sleeve.

You've got a lot of scrap parts on your hand. 

IW

[MikeKato]

It's advertised as a 87 but it's a 78. about a half hr from you. asking $75 but says he's flexible.

http://tampa.craigslist.org/hil/mpo/4299410797.html

[martin99]

Good that you're being so positive about it mate, not sure I would. But as has been pointed out, it's the engine that's mangled, not you!

Are you going to take it apart? It'd be interesting to see exactly what happened.

[rb550four]

I would buy the other $75 motor on CL and do some detective work later. heck, it'll cost you that for rings anyway and you wouldn't be without a runner

[Carver]

It's advertised as a 87 but it's a 78. about a half hr from you. asking $75 but says he's flexible.

http://tampa.craigslist.org/hil/mpo/4299410797.html

I'm gunna give him a call, how much of the engine internals are interchangeable? Looks like im gunna need the crank, pistons, jugs, actually can I just drop this engine in my frame while I build the other one up? I don't see why not Just wanna confirm its possible and none of the mounting points changed over the years.

[Carver]

Good that you're being so positive about it mate, not sure I would. But as has been pointed out, it's the engine that's mangled, not you!

Are you going to take it apart? It'd be interesting to see exactly what happened.

Yeah, the plan right now i guess is to pop the CL engine in if I can get it and then rip this one apart and see how messed up it is and when I get a job build it in to a mild engine for touring which is why I bought the 750 in the first place.

[Don R]

We always used them for mild touring, they just need a good tuneup and a clean set of carbs. That's the beauty of these bikes, they still can be inexpensive. Keep the old motor for projects and parts.

[ekpent]

The CL engine looks like a 78 F engine by looking at it and the other parts. They have a few quirks of their own like valve stems etc, especially if not well cared for. Be careful you don't end up with another junker 

[MikeKato]

The CL engine looks like a 78 F engine by looking at it and the other parts. They have a few quirks of their own like valve stems etc, especially if not well cared for. Be careful you don't end up with another junker 

The guy said the parts were "off a running bike" and I know a person should take that info with a 50lb block of salt but for $75 or less, I would take the chance. Maybe ask the guy if HE heard it run while negotiating and if so,did it smoke. But,again,for $75 or less it's a good bet. Maybe he can get the whole pile of parts(except the hacked up frame) for $125 and come out with the motor free after selling off parts.

[mrbreeze]

If the CL engine a 78F....won't there be a problem with the chain lining up to a K3? I've never owned a 77-78 so I don't know.

[MikeKato]

I was thinking about that too. I know there's 2 different size spacers for the brake side. A member named Radam threw an early (1974?) motor in a 78f a couple years ago but I don't know if he had to change the spacer size.

[Carver]

since we're talking about it does anyone see anything in that pile of parts worth flipping so I can start sourcing parts when I bust the case open? I see gauges, and the exhaust maybe but not sure what to look for on the F series?

[mrbreeze]

I thought he wanted $75 for just the engine. If you get all of that other stuff you can flip a lot of it.

[ekpent]

Read up as there may be some other parts like a sprocket carrier or such that you would need to line up your chain with a 73 frame and 78F engine. Never done it here but plenty of threads. Also pistons etc would not be the best situation for you for parts swap into your K3 motor.