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Discussion Starter · #1 ·
Finished doing the top end rebuild, also took off the starter and chain. The bike started right up on the first kick and idled, however I heard a loud tapping sound. Sounds like it could be coming from the valve cover, like one of the tappets are hitting the cover? I made sure the cam was lined up correctly with the score mark on the alternator before I put the cam chain back on. Also, the bike didn't easily start a second time, but the carbs may be a little rich. Could this tapping sound just be from the lack of oil in the head, and will it go away after it has a few minutes to circulate the oil? Also I made sure to fill the two cam tubs with oil before putting the cover back on.
 

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It could be oil issue like you said. I recently started up my 400 and it had a loud ticking/tapping from the head. Turned out there was a blockage in the orifice that feeds oil to the head (between block and cylinders). Hope this is not your issue but could be. Have you taken off the valve cover to check if there is sufficient oil there? Worth having a look before starting again.
 

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Discussion Starter · #3 ·
Looking at the lube diagram in the manual, it shows the path of the oil going up through two rear engine bolts. Does the oil specifically travel inside the bolt and squirt out the top? Or does it travel between the stud and the engine block? I'll manually dump some oil in through the tappet covers, at least that'll narrow down what the cause of the tapping is.
 

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If you didn't put that cam chain tensioner in there properly i.e. it's not sitting in the bottom damper, it'll come out and flop around causing your cam chain to flop around.
 

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Discussion Starter · #7 ·
See here.
hmm, I did in fact release the tensioner and heard the spring pop, however I was able to thread and tighten it with a 3mm long screw; I was even able to get the slipper height adjusted. If it did pop out, would I still have been able to adjust the slipper?
 

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BerryDuffman said:
See here.
hmm, I did in fact release the tensioner and heard the spring pop, however I was able to thread and tighten it with a 3mm long screw; I was even able to get the slipper height adjusted. If it did pop out, would I still have been able to adjust the slipper?
It would spring up. If your valves are set correctly then i'd be opening up the head cover to have a look.
 

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Discussion Starter · #9 ·
Well bad news. That tapping sound was the sound of an engine with too little oil. I only ran the engine twice for 15-20 seconds each, but it seems the damage was done. Checked the compression with my tester and while it may not be completely accurate, it showed sub 90psi reading on both cylinders, both went 30psi-60psi-90psi, and stayed at ~90psi with each kick. Also couldn't get it started today at all. Any advice? perhaps I should find another cheap 360, with a good engine, and try to use the existing parts I already have?
 

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Discussion Starter · #11 ·
I know it's been asked before but did you have the chokes OFF/OPEN and the throttle wide open??
That's such a great question. I don't think payed any attention to the choke or throttle when I was testing it.
 

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BerryDuffman said:
That's such a great question. I don't think payed any attention to the choke or throttle when I was testing it.
Glad to hear it, hopefully you performed the test incorrectly and thats the reason for the low results. Try it again and see if it improves it.
 

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Phew! I'm glad I mentioned it after all. I figured you'd be like "OF COURSE I DID STUPID!" :lol:

Hopefully it ended up saving you from tearing things down for no reason..


GB :mrgreen:
 

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Discussion Starter · #14 ·
Hopefully, how tolerant are these engines? Can running one for ~20 seconds dry on oil do much damage. I did notice the right cylinder was getting warm.
 

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Its the cam journals that you need to worry about. No oil for any amount of time will end in sudden death! Someone here posted a pic last year of their totally thrashed cam journals but I dont remember who... :roll:
 

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Discussion Starter · #16 ·
Its the cam journals that you need to worry about.
I'll have to look for those pics; that was one thing I did actually remember was to do.

I just checked the compression again, with choke and throttle open, and got some interesting numbers. Both cylinders still went 35-65-90psi. However, when I put a little oil (more spilled then went in to the hole) in the cylinders, the compression went up to 180psi on both within 3 kicks. Could this be an indication of no oil getting to the cylinders as opposed to just shot rings?

...also, should I be able to see oil squirt into the top of the engine by hand cranking it through the tappets?
 

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The oil oozes/flows more than spurts/squirts, (and it will take a bunch of kicking to get it up there) but you HAVE verified you need re-ringing....
 

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BerryDuffman said:
..... However, when I put a little oil (more spilled then went in to the hole) in the cylinders, the compression went up to 180psi on both within 3 kicks. Could this be an indication of no oil getting to the cylinders as opposed to just shot rings?
To take Steve's advice a little further, a giant leap in compression after squirting oil in there generally indicates bad rings.
If there's little or no increase in psi, it generally indicates bad valves.

This is not to say that your valves don't leak - you'll have to test for that later.

But meantime, you're probably not going anywhere with compression that low.......
 

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Discussion Starter · #19 ·
I'm probably gonna try to sell it off. The rings and pistons I put in were used, but in good shape and most likely I damaged them starting it dry. Although not really a huge project to fix, and I already did it once, my neighbor has a cb500 for sale that runs pretty nice and it's in far better shape. :D
 
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