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Discussion Starter · #1 · (Edited)
Bottom End Failure

Hello all,

So this is the 2nd time I have had the bottom end go out on this bike. 1st time was when the bike was bought(reason for sale).
I then did a full rebuild tested the oil pump, cleared oil passages, replaces the crankshaft, connecting rods and connecting rod
bearings, pistons and piston rings. 150psi + - 5 depending on the day. She ran like a top for 1000miles all over town not pushing
it too hard. Then last week major power loss on the highway. Got off and ever since the bike will not produce any power past idle.

The bike is a 1981 CX500c

My two questions:

#1: How come this has happened twice? Are there any tips on this issue?

#2: Is there anyone with a donor Crankshaft/connecting rod set (with bearings)?? or just connecting rod bearings size B??
I am based in Los Angeles if anyone is local or can pay for having it shipped. Would be very grateful.

This is my only real means of transportation and I am looking to fix this asap!

Thank you in advance to anyone able to help,

-Ellington
 

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Hello all,
She ran like a top for 1000miles all over town not pushing
it too hard. Then last week major power loss on the highway. Got off and ever since the bike will not produce any power past idle.

The bike is a 1981 CX500c

My two questions:

#1: How come this has happened twice? Are there any tips on this issue?n
Major power loss on the highway may not necessarily mean bottom end failure per se. Have you done any electrical diagnostics?
"how come this happend twice?" my money is on that it didn't happen twice. Just a new problem.
Do the electrical diagnostics (check the wiki, or such) and see what your results are on that. Also, check your fuel system.
 

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Discussion Starter · #4 ·
Hey thanks for writing back. The other thread is in parts and I didn't ask why this happened there.

I left the bike at a mechanics and that was their diagnosis. They checked everything else, new stator, spark, carb clean, ect.
They diagnosed a bottom end failure either in the main bearings or the connecting rods. Since this happend to the previous
owner I would assume the connecting rod bearing over the main bearings.

There were small flakes of copper on the dipstick but I used copper gasket spray the help seal the heads so I am pretty confident
it was that. (same color as spray and dissipated soon after rebuild)
 

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very much doubt the copper spray would contaminate your oil enough for it to show on the dipstick...why are you using copper coat on head gaskets for??? its made for copper head gaskets not the other type.

search these forums for rod nock check, or similar there is a way to check if you have done a rod bearing by pushing down the piston with a screwdriver but it has to be done a certain way and you will here a audible clunk
 

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While I also doubt using permatex copper gasket spray

Would show in the oil it is an appropriate sealant for the head gaskets and the one I have been using forever

It is not just for copper gaskets and meets Hondas requirement for head gasket sealant
 

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Discussion Starter · #7 ·
Hello All,

Thanks for the responses. The bike does have copper gaskets. The OEM versions were giving me trouble (ones I ordered were frail) so I decided to
run copper ones. They sealed up well and I had no issues with the top end once it was rebuilt. The copper srpay does work on all types of gaskets
and I would recomend it to anyone in need of a little extra grip considering our motors have to deal with multiple mating surfaces thanks to being
water cooled.

Im the meantime I have sourced a new crank shaft, conn rods, conn rod bearings, and a new block so depending on what I find on the inside
of the current motor Ill do the swaps necessary to make it work.

Best,
 

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Murray, I have over 8000 miles on my copper head gaskets. Thay has never given me a problem (Now I did not use Pure copper, but an alloy called Aluminium bronze That is made for what I am using it for.)

You just have to use the right type of copper alloy.
 
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