The CBX lives, then pops a shaft out of the engine...

[Timmay]

Well, On Saturday I put the CBX back together and it ran beautifully.

I took it out for a test ride and...

The cam chain shaft between the camshafts popped out

I took the engine apart expecting the worst but I could find no damage.

I reassembled the engine and it turns over fine but won't start.

So far the list of possibles is:

Damage to the piston - low compression - Can i borrow a compression tester from someone? I live in Birkenhead

Timing changed by a shock to the engine, I am imagining a key way in a shaft which has broken causing the timing to shift.

Does anyone else know what might have happened?

[tri boy]

bent valves.

[FJRider]

There should be timing marks on the cams / shaft that line up.

[Timmay]

everything lines up correctly and the clearances on the valves are correct. I have just had the engine apart to do the head gasket and it ran fine afterwards. Unlikely to be bent valves.

[motorbyclist]

any marks on the piston?

(i assume you've still got spark, fuel, air etc)

[Timmay]

I haven't had the head off to check the piston, I was hoping a compression check would tell me if this is where the problem is. What pressure should I expect on this engine at 53,000km ? I'll go to repco and get a comp check today hopefully.

[jrandom]

I took it out for a test ride and...

The cam chain shaft between the camshafts popped out

TIMMAAAAAAYYYY!

[xwhatsit]

Aww shit. Does sound like valve-hitting-piston time, don't it

I've got a ratty old rubber-plug compression tester here if you get stuck, don't know how accurate it is though (stole it off dad -- he's got three).

[Katman]

Block the sparkplug hole off with your finger (if it will reach) and wind the motor over. You'll feel whether you have compression or not.

[Timmay]

Well I popped the head off and poured water into each port, one intake port is leaking

of to the head shop...

I'm glad it is pay day this week

[xwhatsit]

Probably just valves, don't need to go to cylinder head repairers. When the cams lost the ability to stay in time, the intake valves were open when the piston was coming up.

Two new valves should be cheap enough from Econohonda. Just get some grinding paste and lap them in so they seal nice -- do the same with the exhaust valves too.

[motorbyclist]

heck if you're good you might be able to get the valves straight again too


what does the piston look like?

[Hawkeye]

Sorry to hear that your having problems. My first bike was a CBX250rs. Loved it. Classic little bikes that normally just go and go and go.
Hope you get it sorted out.