Topic: Piston rings in bits

[Calumjs]

Took my barrels off to find my top rings broken and one was in pieces. Is this abnormal? Or is it often  seen? 


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[dave500]

poor assembly or worn ring grooves,was the engine smokey?

[Calumjs]

Yes smoking lots and you could smell the burning oil riding behind it!


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[Calumjs]

Can anyone tell me if the cam groove is worn or will I be okay to use this head?


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[dave500]

cam journals look fine,hows the bores look?the ends of the broken rings are likely to have run some scores down them,ill hazard a guess and imagine some ring bits will have made it down into the crank area aswell?drop the pan and have a look.

[Calumjs]

Bores don't look to bad, couple of bits in the pan. Most of the bits from that broken ring were still in the piston. Looks like the cam chain was ran very loose at some stage you can see it ate the case, is the cam chain tensioner supposed to have those groves in it?


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[dave500]

id replace all the valve chain tensioner components and chain seeing your this far into it,and with broken rings,know its history or recently bought it?measure the bores and pistons or have it done for you.

[Calumjs]

I bought the motor and put it in my bike and ran it for a bit, ran great but was smoking. I'll get the barrels measured and buy appropriate Pistons. What sort of puller do I need to remove the alternator rotor?


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[01Thomas]

If you have a ridge at the top of your bores that will break the top rings quick-quick.

[Whaleman]

If you think it ran "GREAT" with rings like that you won't believe how "GREAT" it will run when properly repaired. Dan

[750cafe]

Perhaps those rings were installed WITHOUT checking the ring end gaps. Mic your pistons and the cylinder bore.

Eric

[Bootsey]

What sort of puller do I need to remove the alternator rotor?


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If the 400's rotor are the same setup as the 550's, you can either buy a puller like this. This is the size for a CB550, not sure whether the CB400 is the same, you'll want to double check. If you do know the size of the thread, you can just get a bolt of the same size from any bolt store,  it will do the same trick.

http://4into1.com/motion-pro-flywheel-puller-m16-x-1-5-external-thread/

[fmctm1sw]

What sort of puller do I need to remove the alternator rotor?


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If the 400's rotor are the same setup as the 550's, you can either buy a puller like this. This is the size for a CB550, not sure whether the CB400 is the same, you'll want to double check. If you do know the size of the thread, you can just get a bolt of the same size from any bolt store,  it will do the same trick.

http://4into1.com/motion-pro-flywheel-puller-m16-x-1-5-external-thread/

+1.  I've always just found an appropriate sized bolt.

[Don R]

 If it was used mildly and wore a ridge at the top of the cylinders and then was run hard out to the redline, the top rings may have seen new territory and stuck on the ridge.
 A buddy did that on an old truck, he replaced the rod bearings and the rings promptly broke. He thought the new bearings pushed the rings up higher. eh?

[Calumjs]

What sort of puller do I need to remove the alternator rotor?


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If the 400's rotor are the same setup as the 550's, you can either buy a puller like this. This is the size for a CB550, not sure whether the CB400 is the same, you'll want to double check. If you do know the size of the thread, you can just get a bolt of the same size from any bolt store,  it will do the same trick.

http://4into1.com/motion-pro-flywheel-puller-m16-x-1-5-external-thread/

So with the bolt I just crank it up and the rotor will pop off?


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[Bootsey]

I imagine its the same as the 550, if so, the end of the crank is tapered where the rotor fits.
Unscrew the bolt holding the rotor on, inside you'll a larger thread than the bolt you just removed. (Possibly M16x1.5)
Thread in the puller/large bolt, use a rattle gun to tighten if you have one.
If not, do it up tight by hand, then hit the end of the bolt with a rubber mallet, then tighten again. Repeat & it should pop off.

[dave500]

not a rubber mallet use a ball peen,not a claw hammer either.

[PeWe]

Those broken rings reminds me about my 736 bore before I repaired and modified the engine.
I was way too eager to drive, not much warming up, full speed most of the time.
The ring grooves in pistons were also worn, vertical which might have been the beginning, later snap rings.

[Calumjs]

Yeah the votes have a ridge up the top and I thrash the absolute crap out of it. Before I split the cases the manual says to pull out the primary drive shaft. I've yanked and yanked how does it come out? What is the shaft that the clutch basket bolts to called?


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[Bootsey]

Not too sure about the 400's, but on the 550's and some other models, the end of the primary shaft is threaded.
On the 550 you can thread in one of the long rear engine mount bolts, and along with a large socket, use it as a slide hammer to remove the primary shaft.
Some other models use one of the axles instead of the mounting bolt.

[dave500]

or remove the oil pump on the other side and knock it through?best to have the oil pump removed for re install anyway?you might clash the gear mesh trying to slip the shaft back in?