2 nd time engine has seized up...need to know where to look.


2 nd time engine has seized up...need to know where to look.

Postby Thunderdome74 » Fri Jan 12, 2018 1:15 pm

Hi guys. So my cbx. I while back I had problems with my cbx.
I was messing with the cam chain tensioner and started it ...the bikes starter wired once and stopped. I couldn't turn the engine over at the crank more than about 320 degrees.

I took the engine to a mate who redid the entire head and valves.piston rings etc. He also took off the sump. Nothing. After removing the head and doing the job the engine was turning over perfectly.


The only thing I have done since was the Oldham couplers and clutch rubeers. She was running beautifully. I took it to my mate and she was running what seemed to be on 5. A few stutters and stuff.

Got to him.parked the bike. When I went to start it it sounded like something had broken loose. A racket. I switches it off after about 2 seconds.

He has since taken the tappet cover off and all the valves and chains (new cam chains) are tight.

I took the clutch off thinking it might been something did (the ground bolts on the clurch housing).

It was all good.

I am getting a borescope to take a look at the pistons etc but I am at a loss at to what else to look at.

Please excuse the formatting as I am on a cellphone.

Any help is really appreciated.

Thor
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Re: 2 nd time engine has seized up...need to know where to l

Postby EMS » Fri Jan 12, 2018 5:03 pm

You sure you installed the cams correctly when you changed the Oldham couplers ? Early service manuals without the update show the wrong procedure.
You could also have "hydrolocked" the motor. Usually affects cylinder No 1 and bike runs badly on 5 afterwards
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Re: 2 nd time engine has seized up...need to know where to l

Postby daves79x » Sat Jan 13, 2018 9:19 am

My bet too is a hydrolock. Knocking is crank weight hitting the bottom of a piston.

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Re: 2 nd time engine has seized up...need to know where to l

Postby broook » Sat Jan 13, 2018 9:25 am

My thoughts too Mike. As soon as I started reading my first thought was the incorrect cam placement. They will run for a short time before the big bang. Never thought of the hydro lock though.
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Re: 2 nd time engine has seized up...need to know where to l

Postby Thunderdome74 » Sat Jan 13, 2018 6:05 pm

Hi

Thanks for the replies but i am back on a keyboard so posibly able to explain better.

I can't be the cams...Initial work done:valves and rings and gaskest)
I've Since done 3000KM before getting the couplers and shims done

How it happened
Bought bike
It had been "repaired by a mechanic"
I had to do alot of carb work before it ran
Fiddled with cc tensioner
swung engine over, (didn't fire) then it locked (i thought it could be hydrolock)
I took the tappet cover off (all cc were still in place along with valves)
I DID FIND THE TACHO CAP HAD BROKEN OFF WHERE IT HOLDS THE TACHO in place/NO PIECE lying about
Where the casting had broken off was not a fresh break(but it had been broken i know not how long)
Chalked it up to mechanics ineptitude
Sent bike to mate
He seated all valves/Rings/Gaskets/new tacho cam cap/valve sten seals
Removed sump to check about the lock.
Nothing and the engine was turning freely and runnign well

I bedded the rings in over 3000km.Bike was running well

Took it back to get shims and oldham couplers done.
Ran great
I did the clutch rubber replacement

Was back at his shop talking old bike talk, and when i went to start it it sounded really rackety like something was bouncing around or had come loose.
Switched off asap

I pulled the clutch to check nothing had come loose, it all looked good
He pulled the tappet cover, all shims, cam chains were good

Upon further discussion we came up with the possibility the original tacho cap bit had broken off with the original mechanic, fallen down the cam tunnel.
This had sat waiting
This had locked somewhere when i did the Timing bit , i theni took it to my mate
When he did the headwork it dislodged itself
Engine turned 360
I ran 3000km etc, until the other day when
i started it it might have bounced around in the engine landing on... Primary chain mebbe?

Does this theory sound plausible... i an not that confident on the X engines.

I will pull the sump but can i chack out most of the engine using a borescope (ie primary chain and sprockets?

Where do you guys thing a piece might land..any help is greatly appreciated as i am really loathe to bottom strip the engine.


Thanks agin Thor
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Re: 2 nd time engine has seized up...need to know where to l

Postby daves79x » Sat Jan 13, 2018 6:20 pm

Very unlikely the broken part would lay somewhere, then jump into a chain in one episode, then clear that only to land somewhere else to repeat the event later. In all likelihood the part fell straight into the sump long ago and was removed before you got it. I think it's time for a complete tear down and inspection.

Dave
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Re: 2 nd time engine has seized up...need to know where to l

Postby Thunderdome74 » Sun Jan 14, 2018 2:32 am

Thanks Dave , your advice is appreciated
Its puzzeling to be sure.

I just want to try exhaust all other options before going that route.(borescope)

When it gets to full lock with a spanner, it is a VERY hard lock..Ie there is no minute give in the spanner, like a valve gives.
A solid lock with no give, goes reverse also easily till full lock stop.
Any ideas what else i can check out?
Sump previously was clean of debris
I am grasping at straws....
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Re: 2 nd time engine has seized up...need to know where to l

Postby Thunderdome74 » Sun Jan 14, 2018 2:34 am

I was thinking starter clutch perhaps?
Somthing there to check out?
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Re: 2 nd time engine has seized up...need to know where to l

Postby daves79x » Sun Jan 14, 2018 8:17 am

Maybe the starter clutch, but I've never heard of it doing that. Cases have to be split to check that anyway. Your description really sounds like now you have one piston seized/locked. You can turn the engine in either direction quite a ways, but not through. A very bent rod will do the same thing - I'm still betting on the hydrolock.

Dave
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Re: 2 nd time engine has seized up...need to know where to l

Postby Thunderdome74 » Sun Jan 14, 2018 5:01 pm

Borescope this week, will update until the problem is found, althout my friend checked with the tappet cover off (hes been working on this old stuff for about 40 years) and thinks the valves are still good.


Will update as i know more
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Re: 2 nd time engine has seized up...need to know where to l

Postby wyly » Tue Jan 16, 2018 5:05 pm

if I recall correctly the tach drive needs to be taken out before the cam cover is removed or it will break on removal of the cover...which could explain a piece migrating about inside...when my engine pushed a rod through the crankcase all the broken bits were found on top of the head, in the bottom of the crankcase or the sump... once in the sump how does it get past the screen?...I don't know any trusted method to search for the suspect broken piece other than a complete tear down...

as too hydro-lock I discussed my engines issues and "5" bent rods with Bert at SCM he says while the dreaded hydrolock usually occurs on number 1 pot he says it can also occur on a number of cylinders simultaneously ...I've never heard of that before but as cbx is the focus of his business I can't dispute what he's come across...
CBX a work in progress, still improving...GS1150EFE completed and awaiting modifications.....RD350, remnants in boxes scattered throughout the garage
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Re: 2 nd time engine has seized up...need to know where to l

Postby Rick Pope » Sun Jan 21, 2018 10:02 am

Hey Dave, remember when Linda Theisen had something go wrong with the pulsar shaft and locked her motor? Just think'n.......
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Re: 2 nd time engine has seized up...need to know where to l

Postby daves79x » Sun Jan 21, 2018 12:21 pm

Yes, I remember the pulser shaft seized in the bore of the clutch cover and I think snapped off. Not likely here, but worth checking since you just have to remove the clutch cover.

Dave
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Re: 2 nd time engine has seized up...need to know where to l

Postby Thunderdome74 » Fri Feb 09, 2018 6:23 pm

Just a quick update. Tappet cover taken off.
cams removed. All the valves looked to be good.
Still locking. Gonna flip then engine over and take off the lower casing and look see. I will update.
On my phone...accounting for the writing. Tx. Thor
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Re: 2 nd time engine has seized up...need to know where to l

Postby daves79x » Fri Feb 09, 2018 6:27 pm

My bet now is still a bent rod.

Dave
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