Hi fellows,

It's been a while since I logged on to the forum. Had a bit of bad luck recently with my CBR. Well... let's just say I should never have let the Wife ride it.
Big hospital bill later (for Her) new fairings, clutch cover, mirrors, exhaust header, frame sliders, JB weld, later, the bike looks good as new again

OK, it has a problem. A problem that has been with the bike since I bought it.
It cuts out when I go over a bump. The MIL light comes on when the engine cuts but it restarts every time. Gives a bit of a lurch but restarts every time.
Here's what I've checked and ruled out.

Battery connections are good.
Fuses are good.
Kill switch cleaned.
BAS bank angle sensor shorted out (bypassed).
Kickstand switch shorted out.
Fuel cut off relay swapped with the headlight relay.
Engine stop relay swapped with the headlight relay.
Fuel pump checked with a separate supply and connections checked.
Engine grounds checked.
Checked for any obvious breaks in wire loom or a loose/broke wire at the ECM plugs.

All above checked. But it still cuts out going over bumps.

Tomorrow I'm going to check the ignition switch.

The bike doesn't have a power commander on it.

Any ideas gentlemen?

Just to add I'm an expat living in Thailand. Very difficult to get spares for these bikes. The local mechanics near me are terrible. I try to do most of the work myself.

Any suggestions, ideas most welcome.

 

What exactly does "cuts out" mean? Does it loose power, or does the the engine just stop running?

 

Hi 74demon,

The engine cuts out completely. If I were to clutch in and coast it to a stop after it happens the engine has cut out. Because the bike is in motion and gear it restarts after the bump in the road has been cleared.

The bike starts first time, every time. It will happily sit stationary with the engine running.

 

It's gotta be something that is loose, a connection somewhere. How big of a bump does it take?

Try wiggling the harness and taping on things while it's running. Unbolt the tank so you can get to the FI harness too. If you can get it to stall, you will have found the trouble spot.

 

Takes quite a bump to trigger it. Roads are terrible here so it happens frequently.
I'll do this tomorrow. Already stripped back the loom at the ecm. Nothing apparent. Probably not connected but the last owner put a separate ground from the fuel pump to battery negative. Somewhere in the loom the ground is open.

Try your idea in the morning. thank you.

 

Just back in.

OK... tried 74demons advice. Took the front inner fairing trim off and took the airbox off to access the ignition plug connectors and the coil pack connector.

Ran the engine and moved the loom and connectors. Flexed them too and couldn't make it cut out! Checked the coil packs and their plugs. Appeared good.

Cleaned every connector with contact cleaner. Put it all back together, took it for a run and it was fine. But I've seen this before then it re-occurs when I hit a bump.

I'm out on it later and fully expect it to cut out again.

Still looking for ideas?

 

Could it be the RR unit which is loosely connected or something? It has to be the main circuit and not peripherals as it shuts off completely.

 

Hi ceebeeaarguy,

Last night I had an idea that my fusebox under the seat might be the cause, as it's not pinned down. I cable tied it down but alas it still cut out one time. But only one time.

What I did notice yesterday was the Stator/RR three phase white plastic plug is a little burnt at one wire. The wire fragile.
And how it's sitting would move quite a lot when going over a bump. I'll run the engine and move the plug a bit.
It's still charging up though. Been through the Stator/RR crispy plug with my Gixxer 1000 recently and it didn't cause the bike to cut out. However I will look at this.

 

the regulator connection won't cause it to just shut off.

keep banging on things until it does it....

 

OK. I pulled up the wiring diag and I agree.

Back to the drawing board. It took a fairly hefty bump to kill it last night. On the way back it didn't cut at all. Maybe something I've did has improved the fault...Lol it's a pain as a brilliant bike and boom it goes off.

The fuel cut and engine stop relays I might replace (if I can source here) with new ones. Swapped the above two around yesterday.
Does any 4 pin 12V relay that fits, do the job? It's just a switch, right!

I might re-visit the kill switch and short it out. Just to be sure. It's an old bike. Got to be a bad connection somewhere.