Selling the CB250RS

Mattberkshire

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Hi. Just placed an ad for the CB250RS in Classic Bike magazine. The ad states £600 ono but I'd take £500. If anyones interested in it let me know. Do you like the pic?
There is a small problem, and it's a wierd one. I get small sparks where the clutch cable meets the lever. I can't work out where it's coming from but it's obviously electrical. All the wiring is spot on. I would of course be honest about this and tell anyone who called me up about the ad!
 

Fred

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You've got a bad ground somewhere between the engine and the frame or between the engine and the battery. So current that should be returning through that ground is taking the only available path it can.

It's going from the engine to clutch cable to tripleclamp to handlebars to steering head bearings to frame to battery negative terminal.

Check and clean all the wires coming from the battery negative to the frame and engine. And see if there's a ground strap between engine and frame. Check and clean that one too.

Also, check the grounding of the ignition coils. The spark may be from the ignition system if the coils aren't properly grounded. The spark should travel from coil to wire to spark plug to cylinder head to engine block to frame to coils.

A bad ground would again have the spark going from coils to wire to spark plug to cylinder head to engine block to clutch cable to etc. etc. etc.

If it gets bad, you'll start to see the clutch cable smoking when you use the starter, as the current is too much for it. It's bad for the cable, and you're also shooting electricity through your steering head bearings, which is really bad for them.
 

Mattberkshire

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Wow, fantastic advice Fred. Where else would I get that kind of info. Thank you thank you thank you.

It doesn't have a starter, it's a kick start. The sparks get worse the higher the revs so presume it's from the coil. I was a complete mechanical novice when I started rebuilding the bike back in October, and I'm still learning!

I'll print off your post and check everything.

Thanks again!!
 

Fred

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Yeah, sounds like a coil grounding issue. If the coil is mounted to the frame, then the problem is probably that the engine is not grounded to the frame properly. As a test, you can add a wire between a bolt on the engine and a bolt on the frame and see if that solves it.
 

Mattberkshire

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Big thanks to Fred. I traced the problem to a missing nut on the ground connection in the coil. Many thanks. I don't get a shock when I change gear now!!
 
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