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Discussion Starter #1
well it happened.
it was a great weekend of ups and downs with my bike. got my new ignition coils mounted up and installed, re-timed the ignition and actually put a few miles on (kind of a clanky noisy sounding bike) before "it" happened. that sound should have thrown up a red flag because after the ignition coil pics(or before), see for your self...

i've chimed in before here about running on one cylinder (cold exhaust on the left, but still decent compression and spark on that side). i should have listened and had the valves professionally looked at but just kept taking my chances. i'll take some pics tonight as i "attempt" to remove the head and see just how bad it is. breaking the cam chain is really the only thing that is scaring me. right now i'm hoping for "just" replacing the exhaust valves and maybe the guides, etc. but am thinking the worst, piston damage. if that's the case i may be in the market for a new engine...

i'm hardly a mechanic but I AM definitely getting more comfortable with working on this bike, however this may be too much for me to handle. thoughts?
 

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uhohferris said:
well it happened.

i've chimed in before here about running on one cylinder (cold exhaust on the left, but still decent compression and spark on that side). i should have listened and had the valves professionally looked at but just kept taking my chances. i'll take some pics tonight as i "attempt" to remove the head and see just how bad it is. breaking the cam chain is really the only thing that is scaring me. right now i'm hoping for "just" replacing the exhaust valves and maybe the guides, etc. but am thinking the worst, piston damage. if that's the case i may be in the market for a new engine...

i'm hardly a mechanic but I AM definitely getting more comfortable with working on this bike, however this may be too much for me to handle. thoughts?
I hate to be the one to tell you but those pieces in the port are not from the valve. Those look like piston pieces or, possible casting pieces from the valve pocket (but probably not).

At the very least you're looking at a complete rebuild including boring and probably valve/valve guide work. Hopefully you didn't bend a rod. There is no doubt in my mind that some pieces probably dropped in to the lower case and that means splitting the cases as well.

Of course this is just speculation on my part based on a couple of fuzzy pictures, but those pieces are definitely not valve scraps.

Sorry to see that. :(
 

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Discussion Starter #3
WOW. pretty much speechless.

however, just after i took these photos i got a call about an inquiry of a new motor... hopefully looking at it today.
 

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Wow! It's kind of what I thought though. Are the valves still in place? Determining what caused that would be interesting.
 

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Holy smoke - I don't think I've ever seen that sort of damage to a 450 piston - more photos as it comes apart, please.........

Is that the mangled piston or broken crap lying on top of the piston??
 

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Many years ago I bought a 200 Ducati Elite with a piston looking like that. Siezed, broke the piston and the connecting rod. Before I opened it up I thought I was in for everything from the deck up (and so did the previous owner) if I was lucky, but the head was OK and all the damage to the cylinder was below the area wiped by the rings. New rod and piston, cylinder bored, hell with the dings at the bottom as long as nothing intruded into the cylinder circumference and the rest of the wall was smooth. Back together, broke it in for a few months, would make over 70 mph, which wasn't bad for a 200cc thumper, probably late fifties vintage. I'd love to have it now, but I made a dirt bike out of it, beat it to hell, and sold it for as much as it cost me.
 

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Discussion Starter #7
one exhaust side valve is completely shot, just the long "rod piece" still remains in place. all others are in good shape, relatively speaking. and yes that crap on top is the piston it self, smashed into a million little pieces like my heart... the tip of the spark plug on that side was smashed as well. there was an arm that connected below the piston, right? again i am not familiar with the inside of this at all, anyway that's gone too. unless i befriend a good old biker machinist that has a sweet spot for old hondas nearby i'll probably just store this until i figure out what to do with it. monmouth county, new jersey? anybody out there?

i think this is as far as i'm going with this engine. i don't even know how to remove the lower half to continue to investigate. ???

good new is i've got some leads on a few used engines, i'll keep you all posted.

broken but not dead,
seth
 

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uhohferris said:
one exhaust side valve is completely shot, just the long "rod piece" still remains in place. all others are in good shape, relatively speaking. and yes that crap on top is the piston it self, smashed into a million little pieces like my heart... the tip of the spark plug on that side was smashed as well. there was an arm that connected below the piston, right? again i am not familiar with the inside of this at all, anyway that's gone too. unless i befriend a good old biker machinist that has a sweet spot for old hondas nearby i'll probably just store this until i figure out what to do with it. monmouth county, new jersey? anybody out there?

i think this is as far as i'm going with this engine. i don't even know how to remove the lower half to continue to investigate. ???

good new is i've got some leads on a few used engines, i'll keep you all posted.

broken but not dead,
seth
Given what you say your experience level is on engines you'd probably be better off getting a replacement engine.

Since all that's left is the valve stem, I'm willing to bet the head of the valve popped of (broke the valve stem) and that's what did all the damage. The "arm" you mention is the connecting rod and that probably bent when the piston came into contact with the broken valve and smashed the piston to bits. Were you revving the motor up pretty high at the time? I've never seen one destroy a piston like that. I've seen valves break and embed the valve into the top of the piston and I've seen valves break and lock up the motor but those pictures are a new one to me.
 

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Bikes without titles usually sell at pretty low prices and they show up on e-bay pretty often. It's a whole parts department, which comes in handy at times. It's sort of a crap shoot what the motor's like, but that's true of buying just the used motor, anyway - and, as far as I can recall, the whole thing often goes for about the price of just the motor. Even if you're going to rebuild, a replacement that hasn't been grenaded might be a better starting point.
 

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Discussion Starter #10
i'm not wasting any time here guys, i've already picked up a replacement motor! 66sprint, thanks for the offer! i am actually curious what shipping would be to be 07756 if you remember and can drop me another line. it was reasonably priced i think and looks to be in working condition. a quick compression test was strong, cams were smoother than on my old engine, old plugs even had nice "tan" tips and the little bit of old residual oil was even fairly clean. i think it must have been sitting for at least 8 years. i'll post more on it's working condition(or not) obviously once i get it in the bike- i'm praying for a "plug and play" scenario- and i'll be looking for help in determining exact year and k1-k6, etc...

one thing, the electrical connections that are coming out of my new replacement motor appear to be a different setup than that of my existing connections. new(used) motor has four bullet connections and my electrical setup has this round plastic "male" (i think) piece waiting for the same round female connection. haha. what do you call that connector? do i just splice in the old connection to my replacement motor? see the new (very dirty) replacement motor pic. and in both pics these ARE the alternators wires, right? also, any suggestions on degreasing the whole thing and cleaning it? on another thread maybe? you guys are all awesome. thanks for the responses...
 

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Discussion Starter #11
uh oh. so i just started thinking about about those electrical connections and model years, of which i don't know for my new replacement. engine says: CB450E-1008963, anyone want to guess? i've read thru all the other posts here about serials and how the frame serial number typically dictate a bikes year, etc...

so, i'm wondering as i sit here at work will this motor even mount to my frame correctly? doh!

my quick looking around tells me the replacement i've got is a 1965-68 CB450K0. think it'll fit correctly into my 1971 CB450K4 frame? tonight will tell, unless somebody gets back to me asap and puts my mind ease.
 

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Discussion Starter #12
i'll save you all the suspense. it's the wrong engine for this bike. cash return, po is real cool about the mix-up.

c-r-a-p.
 

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Sensei
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The engine could have been fitted in your frame.... It's a 4-speed engine... There are several differences internally,and in the carbs, but it would have fit and run the bike.....I'd have kept it IF it ran....... Probably too late for that now...... There are also some minor wiring differences/color coding as you found out already, but they are easily overcome....
 

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Discussion Starter #14
i still have the engine i just told the seller that i thought it was off. which it was. new brackets, and down grading to a four speed, ehh. additionally wouldn't my rear sprocket ratio or something be off as well? steve, i just sent you a message, hopefully your reading...
 

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Just tried to phone..... Also sent e-mail with my contact info....
 

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The five speed gearbox (entire, not parts from each) from your blown motor should fit into the case of the new motor - I don't think there are any differences among the several models in that part of the case, and that would be worth changing. I'm sure you can get more certain info on this from other members. Also, I think there might be a small chance you could have a 360º crank - not that it makes a difference in usefulness, but it would be a real collectors item. The 360º crank motor would have only one set of breaker points, not two as in your blown motor. That would mean you'd need a different (dual secondary) ignition coil.
 

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Discussion Starter #17
just thought i'd share some more carnage as i've gotten into the cylinder head and dissected everything. this is actually fun but of course i'd rather be riding... and i can't ever imagine putting it all back together correctly! or maybe i can, hmmm?
 

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Sensei
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Seth, Looks like your work is cut out for you.... Any word on that CL engine yet?
 

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Discussion Starter #20
hopefully an answer tonight on wether the CL is useable or not Steve, it's available but useable is the question. looking at it in a few hours. i'll keep you posted...

if i attempt to take the piston "head" portion/case/section of the engine off to inspect my exploded piston, are there any bolts to undo? is it just sitting on the lowest section of the motor. do i first have to get into the crankcase and then work up?
 
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