Freshly rebuilt CB360 engine, started up and horrible belt-like squealing noise

mrjoshzombie

mrjoshzombie

Been Around the Block
So, I'm rebuilding my engine again for the 3rd time (first time cam sprocket bolt backed out and wrecked havoc, second time piston rings just broke). Fresh pistons, new rings, new cylinder jugs. All new gaskets on the whole thing, cam and rockers don't have a single mark on them at all.

I've become some-what skilled at tearing this motor apart and putting it back together, but this one is new. After getting it all together, setting the time, tappets, cam chain, tossing in 93 octane gas, and hitting the starter, it kicked straight on and made some horrible squealing noises. Killed the engine, looked around. Turned it over again, same thing, and killed it immediately. Pulled my plugs so it wouldn't kick on, used the starter to turn it over, and sure enough, still a slow squeal as the engine rotated.

Already have the rocker box pulled off and the cam out, I can't see anything I obviously installed wrong, no damages on the cam or rockers, chain was still taught.

What was that noise and what should I be looking for before putting this back together again tomorrow?
 
Did you apply any oil to the top end before assembling? It will take no less than 40 seconds for oil to arrive at the top end.

Why 93 octane? Use the lowest octane you can get without knocking. I end up with 87 in all of mine. There is no "premium" product in higher octane fuels that "burns cleaner" or creates more power, it just is harder to ignite.

If you're reading the manual, remember that's measured in RON.
 
Yup, lubed the hell out of everything, filled my journals with oil, cam chain, etc.

93 was suggested from a friend that knows a helluva lot more about timing/ignition than I do, and he suggested I try running it as the possibility of my rings failing was due to detonation... or... something. I honestly can't 100% recall the conversation, I just came to the conclusion to give 93 a shot.
 
The squealing you're describing reminds me of a motor we turned over that was dry as. Hadn't seen oil in over a decade and was missing the head. It was a nails-on-chalkboard sound that was probably the rings.

As for octane, start with the lowest you have in your area, 87 or 89, and if you detect any knock or if a knock develops as compression grows trough use, go one rating up. I'm always amused by the guys in pre-owned-and-still-financing Lexus' or Mazdas that brag their engine has never seen "that regular grade crap" when the filler door actually says to use 89. Now you will be amused too.

Btw, 87 is usually (R+M)/2. It will be in small print below the large number on the pump selections.
 
there was a guy posted here recently and the squealing noise was the intake gasket,like the reed in a clarinet
 
Oh yeah, if it sounds like a chirping canary, you might have over-tightened or misaligned your intake insulators, the gasket may have been left out or misaligned etc.
 
Is the sound a constant sound, or does it change pitch with the revs? What I would do is change the oil and look for metal. Wouldn't hurt to look in the filter and the pickup screen too. Make sure you have the cam chain tensioner properly seated at the bottom. It's easy to think it's in there when it's not.
 
I honestly wouldn't be surprised if it was my intake. I noticed old gasket on the boots, so I did everything I could to scrap it off and I don't believe I got 100% of it removed. I might be a bit annoyed that I ripped my head off and it's just the intake haha.

I didn't leave it running long enough to play with the revs (didn't want to risk damaging a thing), seemed pretty consistent, straight up like squealing belt.

I'll double check everything when I put it together tomorrow, change the oil like suggested, and certainly play with my intake. Here's hoping it's just something stupid like that.
 
On a side note: did you change out the stock pickup for the CJ pickup amidst your rebuilds?
 
The 360's are notorious for their oil issues. One recall was for the oil pickup. It struggles to draw oil while the bike is on the side stand. The fix is to replace the CB pickup with a larger CJ pickup. It's a direct fit.

honda_42_zpsf1aec5ec.jpg
 
I know about the oil issues, and the recalls, but was apparently unaware of this one. Hm. I'll have to start looking around.
 
Just about everyone was ignorant of the modified oil pick up, it's stock on all CJ's and late model 360's though
I sent Trek the information he's got it on his blog/website
As long as you keep an eye on oil level and don't leave it running on side stand there shouldn't be an issue
 
Alright, so, I've started to reassemble everything. Reinstalled my cam and sprocket, kept the rocker box off, spun the engine, no noise.

Installed rocker box, left the spark plugs out, spun the engine, no noise.

Installed the spark plugs, kept spark and fuel off, spun the engine, chirping/squeaking noise.

Likely my intake boots, eh?
 
Chirping is air. Just remove the rubber insulators and if the noise stops, you probably have a warped insulator or bad gasket/pieces of gasket still remaining.

This is a canary I caught last year. I had an XS650 just last month that had obviously had the insulators over-tightened and warped so they wouldn't seal.
 

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Yup, I swapped them for a spare set I had, and sure enough, all is well.

Outside of smoking from the exhaust (could be old oil in the exhaust burning up from when the rings broke and it puked oil everywhere), I have it running well again after 3 months of ignoring the damn thing.

Thanks everyone.
 
On non-running engine being turned overby kick or electric starter, it's way more likely to be the head gasket leaking. On running engine there be enough vacuum even at idle to cause intake leak resonator, low speed when starting, no way
Real common to have base gasket on two stroke motors act like a reed in clarinet but on a four stroke, unless you have engine breather blocked, there shouldn't be enough pressure 'underneath' the pistons. Saying that, have you checked the gasket on breather cover? could be it wasn't cut quite right?
 
Crazy, stranger things have happened eh? I was working on an XS650 about a month ago and I was kicking it over and it was chirping from BOTH insulators. Was immediately resolved with fresh rubber and gaskets.
 
Yep, I didn't read post correctly, thought it was still being turned over slow. 650 shifts a lot more air and if idle was too low it can't go through the carb so it goes around it ;D (I also have a couple of 650's I've ignored last several years :-[ )
 
Sounds like all is well but I'll add one thing for future readers. I reassembled a 360 one time and accidentally did not get the front cam chain tensioner in the right place. I didn't get it in the little "pocket" on the bottom side. When I kicked over my freshly rebuilt engine it shredded and made a chirping sound as it ripped the tensioner to small bits. Needless to say I had t I rebuild the top and bottom end to get all the metal out. I wouldn't wish that mistake on an enemy. Not to mention the rareness of those tensioners.


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