Very bad running.

[Bradders]

Evening all,

Riding into work this afternoon when suddenly my bike loses power, runs very rough and noisy. It now won’t rev above 4,000 rpm and stalls anywhere near tickover. It’s all happened very suddenly and has up until now been running nicely. Any ideas where I should start looking and what might be wrong with it? Thanks in advance.

[Sesman]

Start looking in gumtree..😁

[Sesman]

Seriously though, start with fuel and move onto ignition?

[K2-K6]

Start it from cold, run for 20 sec, check if all exhaust pipes are warm at the head.

If you've two cold, it's likely one of the ignition circuits, so which one's if that's the case.

[Bradders]

Start looking in gumtree..😁

I must admit it sounded terminal!

[Athame57]

I remember having this kind of trouble a few years back, bike forever on two pistons. I'm sure I just changed the coil belonging to the offending pistons and that solved it.

[Sesman]

Yes, must admit the diagnostic process can be a real challenge, especially for me. Stay with it and keep us updated, we always get there in the end. Could be as simple as a broken wire or restricted fuel flow.

[robvangulik]

Or restricted air flow, not by any chance put your gloves under the seat, or rain gear...

[Bradders]

Thanks for your replies guys, hopefully 🙏 it will be something simple.

[Oddjob]

Thanks for your replies guys, hopefully 🙏 it will be something simple.

Roo then.

Sorry Roo, couldn’t resist.

[Laverdaroo]

Ooo, underhand Shot from Stockport there


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[Bradders]

Morning.  Have had a quick look at my bikes running problems. Started and switched off as suggested after 20 seconds and it appeared that 2 and especially 3 exhaust pipes were cooler than 1and4.
Changed the plugs but still the same, took off the points cover and started the bike again and the points for 2 and 3 are sparking like mad! Any ideas why that might be? Sorry my knowledge is very limited.

[McCabe-Thiele (Ted)]

What is the visual condition of your coil and leads at the coil under the tank?

Is there any sign of the outside of the leads being cracked especially where they exit the coils. You might see some arcing of the spark if it's dark enough or an absence of spark  at the plug end.

[Bradders]

The coil leads look fine with no cracking or arching. Am I right in thinking a bad condenser could cause points arcing?

[McCabe-Thiele (Ted)]

Condensers are a magic little cylinder to me they can work perfectly  for years then suddenly fail or give trouble.

Apparently reliable new ones can be hard to find - others here will give you sources.