Author Topic: CB650 Nighthawk Starter Motor Problem  (Read 650 times)

Offline Clunker

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CB650 Nighthawk Starter Motor Problem
« on: June 21, 2017, 11:08:15 AM »
Hi folks, help needed with my new purchase, US import CB650 Nighthawk SOHC. When I try the electric start I get a clunking sound like like cogs mashing together. My question is, does this sound like a starter motor or starter clutch issue, or even both? It sounds like the cogs are slipping and doesn't turn the motor over, I rocked the bike forward and backward in gear then tried the starter again and it seemed to turn the engine for a second or two then made the same clunking sound. All I have done is pull the starter motor and looked at the cog which seemed fine, then stuck my finger in the hole and rotated the gear inside, it went clockwise freely but only went so far the other way then locked.
Usually sat on a bucket polishing my nuts.

Offline mike the bike

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Re: CB650 Nighthawk Starter Motor Problem
« Reply #1 on: June 21, 2017, 06:47:18 PM »
It's supposed to only turn one direction,  it's the roller clutch mechanism.   It does sound a bit drastic and will probably need stripping.
German reliability is a myth spread by the Hitler Youth

Offline Clunker

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Re: CB650 Nighthawk Starter Motor Problem
« Reply #2 on: June 21, 2017, 06:54:55 PM »
Thanks for your reply Mike. I've got an idea to put the starter motor from my CB650C on to the Nighthawk and see what the result is. I want to try the easiest options first, I've read on the interwebby that if it is the starter clutch then it is possible to repair it without taking the engine out. I'm hoping that it is just the starter motor that is at fault.
Usually sat on a bucket polishing my nuts.

Offline mike the bike

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Re: CB650 Nighthawk Starter Motor Problem
« Reply #3 on: June 21, 2017, 08:22:00 PM »
That's great if you've got a spare starter motor,  lets hope it's that that's faulty but it does sound like the starter clutch.   Pity you haven't got a kickstart
German reliability is a myth spread by the Hitler Youth

Offline Clunker

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Re: CB650 Nighthawk Starter Motor Problem
« Reply #4 on: June 21, 2017, 09:23:11 PM »
No kick start and nowhere to bump start it either. I haven't had the bike running at all yet, it was sold as a non runner but I've always wanted one so to me it is just a minor inconvenience. I'll start spannering in the morning so I'll let you know what occurs.
Usually sat on a bucket polishing my nuts.

Offline mike the bike

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Re: CB650 Nighthawk Starter Motor Problem
« Reply #5 on: June 21, 2017, 09:45:47 PM »
Nice looking bike that, hope it's nothing serious and you get to ride it soon.
German reliability is a myth spread by the Hitler Youth

Offline Clunker

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Re: CB650 Nighthawk Starter Motor Problem
« Reply #6 on: June 22, 2017, 09:41:06 AM »
So far this morning: removed seat, tank, side panels. Removed plugs, tried starter and engine turned over without load, tried starter a couple more times and it turned over and slipped again. Removed battery and put it on charge, removed starter, the on the starter motor is showing signs of wear, the starter cog in the engine looks good with no missing teeth. Took pictures so that I could enlarge them, you get to see more detail than with just eyes alone. Next step, replace Nighthawk starter with CB650C starter and see what happens. One final point, Nighthawk starter motor came out way too easy, looks like the O ring is shot as signs of long time oil leak, possible starter motor wobbling about due to O ring wear???
Usually sat on a bucket polishing my nuts.

Offline Clunker

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Re: CB650 Nighthawk Starter Motor Problem
« Reply #7 on: June 22, 2017, 09:43:07 AM »
Cog inside seems good.
Usually sat on a bucket polishing my nuts.

Offline mike the bike

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Re: CB650 Nighthawk Starter Motor Problem
« Reply #8 on: June 22, 2017, 10:19:08 AM »
What's it like with the spare starter motor?
German reliability is a myth spread by the Hitler Youth

Offline Clunker

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Re: CB650 Nighthawk Starter Motor Problem
« Reply #9 on: June 22, 2017, 10:27:46 AM »
Hi Mike.........splutter, fart, bang, pop.....ROAR!!!!! ;D According to PO she's not been started for a while, I let her warm up a bit then switched her off, started her again but it still slipped a bit, as soon as it catches she fires up on all four straight away.
Usually sat on a bucket polishing my nuts.

Offline Clunker

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Re: CB650 Nighthawk Starter Motor Problem
« Reply #10 on: June 22, 2017, 10:31:30 AM »
Can the cog on the starter motor be replaced? If so, are the still available to buy?
Usually sat on a bucket polishing my nuts.

Offline Oddjob

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Re: CB650 Nighthawk Starter Motor Problem
« Reply #11 on: June 22, 2017, 01:27:20 PM »
I'd imagine the starter motor is the same one used on the 500/550, there are loads of those around.

My feelings are that it's the rollers in the starter clutch, which if I remember right live inside the primary drive housing. If it's the same as the 500/550 housing and I'm fairly sure it is then you can remove it from underneath the engine, through the oil pan hole. You'd need to remove the clutch cover to remove the primary drive shaft but it should be doable.
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Offline Clunker

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Re: CB650 Nighthawk Starter Motor Problem
« Reply #12 on: June 23, 2017, 05:50:51 AM »
Hi Oddjob and thanks. I've got a spare engine (minus the head) so I'm going to try it on that first, I can turn that one upside down to see exactly what's what. The main priority was getting the "Old Girl" to fire up, I needed to know that I hadn't bought a dud. :)
Usually sat on a bucket polishing my nuts.