Need Help fast

A few months ago I had to examine a CX that had run fine for

50 miles after the ( second hand) engine was installed then it suddenly locked up

just as he got home and right outside his garage door.

This was kind of lucky in that it didnt happen at speed.



One theory was the cam chain had snapped.

Anyway, motor dropped, back off and the cam chain etc was all fine

I found I could turn the motor one way then the other but at certain

positions near RH TDC, it stopped dead.



"Aha! Dropped valve" says I

Well it was and it wasnt

Some outer parts of the exhaust valve had broken off and by the looks of it

had been bouncing around a lttle bit before jamming between the

valve and piston.



I'm not saying this is your problem Mike and hope it isnt but

it has to be a possibilty



Its too serious not to drop the motor and examine anyway

Best case scenario may be a broken chain guide jamming the works

Good luck!

I doubt it Mike

lets say it seized to the rotor

The starter would be driven by the engine at all times

but the engine itself would stiil spin normally when you put a socket on the front



take the plugs out an get a good strong torch and move each piston up and down

as much as you can and see if there's any sign of damage



If you remove the rear cover first before you touch the heads and you're lucky enough

to find something fixable, you wont have to disturb the heads



Its possible something broka and jammed between the chain and gears

lets hope its anything but dropping a valve as thats bad news!

OK,

So, found the problem its actually incredible - I couldn't check the pistons, as the motor wouldn't move enough to let me inspect them fully.



Took the rear cover off, couldn't find anything binding it up, and started to get a bit worried. So, I tok the cam chain cover off, and guess what pops out? A ball bearing. I think it was from the steering stem... it must have bounced in there through the inspection port cover, I guess. When the engine was running it must have worked its way into near the cam chain.



Got rid of the ball, and like magic the engine spins free. Problem is that now I need a rear cover gasket, I was supposed to be going on a 4 day motorcycle ride this weekend, so I need to find a gasket close by or get one overnighted to me. Anyone know of a place that has them and does rush shipping?





Mike

You can buy gasket material by the roll and cut your own if your in a pinch/hurry/obsolete.

FOD eh?

tut tut !!



Well its a hell of a lot better than a dropped valve

I suggest you carefully check the affected parts

and cam chain for damage before reassembly



rear cover gasket:

I make my own so can you if your allowed to play with sharp things

and can source gasket paper about 20 by 16 inches ( 18X14 may do, its been a while)

and .8mm or 1/32" thick



EDIT:

Just remembered I have an aftermarlet one in the kitchen

and measured it.

Its .51mm ( 1/50th of an inch) so thinner than my home brew ones so you have a bit of latitude there.

Absolute minimum length and breadth is

16" high and 12" wide

I once dropped the ball bearing from my kill switch down the spark plug hole in the head of my XL-100 while

taking the kill switch apart, the handle bars were turned all the way to the right,,,I saw it go in the hole

though and was able to get it out with a small magnet on a piece of wire.

Billrod said:

I guess I am a little puzzled as to how a ball bearing from the steering stem could get inside the engine through the inspection port. That would need to be one hell of a bounce. I would also think that getting jammed inside the engine could possibly cause some other damage. Hmmmmmm BillRod

Click to expand...

I can understand why it would seem puzzling - I actually did the steering bearings yesterday, and did the cam adjustment / tappet check today. Only thing I can think, is that when the balls spilled out of the steering head, some must have landed back somewhere, where they got jostled and fell into the open port.



Funny thing is, I was just going to go for a ride instead of mess with the tappets, but figured the engine was cold so why not.....



What are the frickin chances of a BB going into that port anyway?? I mean come on...



I prefer the honda gasket for the rear case, I had an aftermarket one that didn't hold up, the honda ones seem to hold up well. Last time I tried to cut one it didn't work out all the well for me either, ended up leaking on me.



Mike