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CB550F Gradually losing power and stopping...

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Steph550:
Hi all,

I've also posted this on the US forum so apologies if you've already seen it there.

Went out for a nice evening's ride on my CB550F yesterday, and broke down no less than 4 times on the way home!! I'm just about to start investigating the problem and wondered whether any of you guys would be able to shed any light on it...

The bike hasn't been out a lot recently, has been sitting in the garage and run occasionally. Got her out on Tuesday, filled her up with petrol and went for around a 15 mile ride. No issues at all. Then on Friday went for a 50 mile ride and the bike didn't miss a beat. Yesterday, rode for 5 miles with no problems, and stopped off at a pub.

After that, things started going wrong. Left the pub, got around 2 miles down the road and started losing power. Then she stopped completely, and I pulled over. At this point I realised I'd been an idiot and forgotten to turn the fuel on when leaving the pub, so turned it on and tried to start the bike. Strangely, she didn't start after several attempts... I wheeled her over to a safer spot, sat and contemplated for a bit then tried again, and she started immediately. I rode on, thinking "that's a bit strange" but she seemed to be behaving herself. However, another two miles down the road I started losing power again, losing one cylinder at a time. It would pick up if I opened the throttle fairly sharply, but got progressively worse, then stopped. This time the fuel was definitely on. Pulled over, tried to start, no joy. Fiddled with things, tried switching the fuel onto reserve, made no difference. Waited a few minutes, and she started normally.

Another two miles down the road, repeated the same process. And then again just before I got home!

It's not a battery issue because the electric start is turning over perfectly. Trying to kick start her makes no difference.

Has anyone had anything like this before? Just about to go and break down again then see if there's a spark or not...

I'd be grateful for any advice.

Thanks,

Steph.

Bitsa (Ralph Wright - RIP):
Steph
Sounds to me fuel starvation.Check the vent in the filler cap is clear because as you say when leaving it a few minutes it fires up again that's because the carbs are slowly filling up again.While you are at it I would check all the fuel system tap filter etc.
Hope this helps you
Bitsa

LesterPiglet:
I'm with bitsa. Unscrew the carb drains and see if any crud comes out. Do you have an inline fuel filter? Maybe this is blocked.

Bryanj:
Another p[ossibility is the charging system not working and after a while the battery recovers enough to allow a re-start. I've had it happen to me

matthewmosse:
A friend of mine had his bike do this several times, he'd far more expirience and knowledge of bikes than me but still ended up stranded. I went back up there with him to collect the abandoned machine and after some head sctatching I spotted the fuel pipe had a slight kink in it which was restricting fuel flow. Also check fuel cap vents, tap might be in need of a clean as said above.

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