SOHC.co.uk Forums > CB350/400

I think I've done something wrong!

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SeanFD:
Hi all, Happy Christmas.

With nothing else to do before dinner this afternoon, i decided to use the time to try, finally to get my 400F2 running; yes the same one I started resurrecting during the pandemic.

Anyway, I sorted some minor electrical problems and power was getting to where it was supposed to be (and when). Even thought the battery voltage had fallen to 12,4 or thereabouts, I decided to try and start it up. 

It coughed once on the kick start and then nothing. I tried it on the started and then I was hit on the head by the air filter cover.

Here I stopped, as dinner was nearly ready, and I wasn't sure exactly what this meant.

Can anyone explain and advise whether it is safe to try again with a fully charged battery, or have I done something seriously wrong in the rebuild?

K2-K6:
You can get a intake "backfire" in a healthy engine with build up of fuel vapour while trying to start a reluctant engine. Possibly not much wrong.

 But, if there’s more common confusion in ignition system on these engine, coils connected to wrong plugs or points firing the wrong coil when inlet valve can be open, when it'll do it more easily.

Assuming no obvious mechanical conflict, then check carefully the ignition wire routing etc against manual to see if there's anything obviously wrong.

McCabe-Thiele (Ted):
I agree check the timing/ firing order reads like a back fire.

SeanFD:
Good call guys, that's exactly what the problem was; I had attached leads to wrong plugs.  :-[

But now something is DEFINITELY WRONG!

Started on first press of the switch and ran quite sweetly. Stopped and started again, and then:

https://youtu.be/c-6r2hDONYw

Now the motor won't turn over with either the starter of the kickstart  :( :(

The oil pressure light went out almost at once and I can see there is oil up at the valves, so my thought is that it is related to the cam chain rather than a seized piston. I can rock the crank a few degrees using the nut on the points end but nothing more.

HELP, please! And be gentle with the bad news.

Nurse Julie:
As it happened so quickly, I would say something has snapped or jammed.
Edit..... Also, if you've got oil to the cam, that doesn't mean it's not a seized piston. The oil to the top end comes up a different oilway.

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