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Author Topic: Starter Issues  (Read 905 times)

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Offline knowsnothing

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Starter Issues
« on: May 27, 2020, 01:00:50 PM »
Hi All,

I am so close to getting a running bike, 78 cb750k, after 10+ years  I can taste it.  Then all of a sudden I stared having a starter problem and I can't seem to figure out what the issue is.  I am going to try to attach a short example video.

When I press the start button, starter begins to work, then sounds like it disconnects? and just spins freely.  I have check the starter gear install, gear/washer/rod all look good.  Even replaced them with ones i had from another engine.   Everything looks as it should to me.  The teeth on the starter themselves also look fine to me, no chips/missing teeth. 

This a fresh engine rebuild. 811cc, ported head and has run for a short time before i started chasing problems.  Any ideas would be much appreciated.

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1978 CB750k Green - 811 engine
1978 CB750k Blue - for sale
1974 CB375F Faded Black - had to have that 6th gear
1976 CB400F Red - in many pieces
1973 CB350F TBD - in many pieces

Offline bryanj

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Re: Starter Issues
« Reply #1 on: May 27, 2020, 01:22:33 PM »
Starter clutch on back of generator rotor, you may get away with new rollers, pins and springs. Sometimes need new clutch bodyand large gear
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Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

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Offline knowsnothing

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Re: Starter Issues
« Reply #2 on: May 27, 2020, 01:41:31 PM »
Quote from: bryanj on May 27, 2020, 01:22:33 PM
Starter clutch on back of generator rotor, you may get away with new rollers, pins and springs. Sometimes need new clutch bodyand large gear

Oh boy, ok so big bolt out, rotor off, i can get to everything?

Thank you bryan
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1978 CB750k Green - 811 engine
1978 CB750k Blue - for sale
1974 CB375F Faded Black - had to have that 6th gear
1976 CB400F Red - in many pieces
1973 CB350F TBD - in many pieces

Offline MauiK3

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Re: Starter Issues
« Reply #3 on: May 27, 2020, 03:12:03 PM »
You may need the tool to get the rotor off.
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Offline knowsnothing

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Re: Starter Issues
« Reply #4 on: May 27, 2020, 03:43:31 PM »
Quote from: MauiK3 on May 27, 2020, 03:12:03 PM
You may need the tool to get the rotor off.

Good to know, thanks
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1978 CB750k Green - 811 engine
1978 CB750k Blue - for sale
1974 CB375F Faded Black - had to have that 6th gear
1976 CB400F Red - in many pieces
1973 CB350F TBD - in many pieces

Offline ekpent

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Re: Starter Issues
« Reply #5 on: May 27, 2020, 03:46:01 PM »
 As the guys said its your starter clutch. I'm curious as to what brand your 811 kit is. Wiseco used to make a nice 811 with 10.5 compression. Friend had one and it ran very well.Think its been discontinued for a long time.
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Offline knowsnothing

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Re: Starter Issues
« Reply #6 on: May 27, 2020, 04:26:16 PM »
Quote from: ekpent on May 27, 2020, 03:46:01 PM
As the guys said its your starter clutch. I'm curious as to what brand your 811 kit is. Wiseco used to make a nice 811 with 10.5 compression. Friend had one and it ran very well.Think its been discontinued for a long time.

It was an old yoshi kit i picked up here 5-6 years ago.  Came in the boxes and everything
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1978 CB750k Green - 811 engine
1978 CB750k Blue - for sale
1974 CB375F Faded Black - had to have that 6th gear
1976 CB400F Red - in many pieces
1973 CB350F TBD - in many pieces

Offline scottly

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Re: Starter Issues
« Reply #7 on: May 27, 2020, 05:02:37 PM »
The usual culprit is the hub of the big gear. Check it closely for wear, as well as the rollers. Also, make sure the rotor bolt is tight; the only thing locking the rotor to the crank is the taper, and if loose the rotor can spin on the crank.
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Offline bryanj

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Re: Starter Issues
« Reply #8 on: May 27, 2020, 10:50:37 PM »
I have "found" the kit i knew i had that somebody wanted a long time back.
It is a nos big gear, clutch ass, rollers and pins but i lost the springs, as i dont work on 750's any more its up for grobs at a reasonable price plus postage from UK
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Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!
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