Author Topic: starter motor safety unit bypass  (Read 5795 times)

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jscro73

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starter motor safety unit bypass
« on: October 24, 2009, 09:05:49 pm »
guys,

how can i bypass the starter motor safety unit on my 73 cb750?
i read some of the other posts, but none really said anything about actually removing the unit and clutch switch and being able to successfully start the bike.
thanks,
Jason

Offline Spanner 1

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Re: starter motor safety unit bypass
« Reply #1 on: October 24, 2009, 09:23:55 pm »
If you unplug the SSU and remove it you can by-pass it's function by jumping the solid Green wire to the Dark Green/Red wire( there is also a light green/red ). That's it, your done........the starter will now spin whether your in gear or N or clutch is pulled or not...  N light will still work when in N 'tho...........

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Re: starter motor safety unit bypass
« Reply #2 on: October 25, 2009, 08:31:49 am »
More info in reply by Hondaman today in post for CB750 RH switch compatibility.Bill
1993 HRC RS125 - 1984 NS400R - 1974 Honda CB750/836cc(Calendar Girl) - 1972 CB 500/550 Yoshi Kitted 590cc -1965 Honda CB450 Black Bomber,'1972 Suzuki T350,1973 88cc Z50 /Falcons pit bike,'67 CA100,
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Offline MJL

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Re: starter motor safety unit bypass
« Reply #3 on: October 25, 2009, 12:06:54 pm »
Since he clutch lever switch was broken on my 750, I followed those wires into the headlight bucket and basically plugged them into each other. Just don't hit the button without double checking first or being on the bike.
No matter how fast or how far I rode, I couldn't leave her memory behind.

Offline Spanner 1

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Re: starter motor safety unit bypass
« Reply #4 on: October 25, 2009, 08:12:36 pm »
Sorry but Hondaman's post in the thread referenced by ' bellcow ' is wrong......a black +12V would never go to a Green-with-red-tracer as it is a switched ground...i.e. it is a ground wire when in Neutral or some other switched condition..... sorry ,but my post of 1 jumper between two wires is correct if you really want to do away with the safety switch ( no start in gear or no start without clutch pulled if in gear, start as usual in N , starter engages any time you hit the button if by-passed )

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Re: starter motor safety unit bypass
« Reply #5 on: October 25, 2009, 08:27:07 pm »
Sorry but Hondaman's post in the thread referenced by ' bellcow ' is wrong......a black +12V would never go to a Green-with-red-tracer as it is a switched ground...i.e. it is a ground wire when in Neutral or some other switched condition..... sorry ,but my post of 1 jumper between two wires is correct if you really want to do away with the safety switch ( no start in gear or no start without clutch pulled if in gear, start as usual in N , starter engages any time you hit the button if by-passed )

You missed something, there: the GREEN-RED wire I'm referring to is about 2" long, and it is attached to the Starter solenoid. It's not tied to the harness's GREEN-RED wire at all.

Because, if it was, you'd be absolutely right...  ;)
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Offline Spanner 1

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Re: starter motor safety unit bypass
« Reply #6 on: October 25, 2009, 08:51:47 pm »
With respect, the original posters question was concerning K3 wiring( actually up to K5 ) where the green/red was a switched ground...wait, no, K6,7,8 F1,F2, still a switched ground...even K0 ( light green/red )......green/red on the solenoid is also a switched ground..i.e. waiting for the trans. to be in N or the clutch to be pulled to send ground to the solenoid.....
« Last Edit: October 25, 2009, 08:58:12 pm by Spanner 1 »

Offline the technological J

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Re: starter motor safety unit bypass
« Reply #7 on: October 25, 2009, 09:51:08 pm »
With respect, the original posters question was concerning K3 wiring( actually up to K5 ) where the green/red was a switched ground...wait, no, K6,7,8 F1,F2, still a switched ground...even K0 ( light green/red )......green/red on the solenoid is also a switched ground..i.e. waiting for the trans. to be in N or the clutch to be pulled to send ground to the solenoid.....
you know that fine line between genious and insanity...... ur there guys..ur there

jscro73

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Re: starter motor safety unit bypass
« Reply #8 on: October 26, 2009, 11:21:05 am »
bellcow, i may just bring it over to you, if you're willing to take a look at it. i live in hiram. i'm getting frustrated with this bike. before barber, i was getting no spark anywhere (coils and points), came back from barber, found out that i didnt put the insulator between the power wires and the grounds @ the points. then, drained my battery, and when i recharged my battery, the solenoid just clicked. then i put a new set of handle bars on the bike. Now, the starter button wont work, but i've got spark @ the points, but i think my starter safety unit is bad, so i wanted to bypass the whole thing for the time being. I dont think the switch is bad. i ran several tests on the wires to make sure i didnt cut anything, and i have continuity. i'm gonna test the switch tonight.

jason

Offline lucky

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Re: starter motor safety unit bypass
« Reply #9 on: November 29, 2011, 09:46:03 am »
If you unplug the SSU and remove it you can by-pass it's function by jumping the solid Green wire to the Dark Green/Red wire( there is also a light green/red ). That's it, your done........the starter will now spin whether your in gear or N or clutch is pulled or not...  N light will still work when in N 'tho...........

Solid Green wire from WHERE? (the harness- safety unit plug in?)
"to the Dark Green/Red wire (where?) On the safety unit harness- plug in?

Or do you mean on the solenoid itself?

Not clear at all.
Can you tell us where these two wires are at that you are jumping? Thanks.

Offline Toxic

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Re: starter motor safety unit bypass
« Reply #10 on: November 29, 2011, 11:02:37 am »
When you unplug  the SSU you are left with a red multi pin connector, you make a jumper wire to go from the green/red to the solid green.
If you don't have the SSU plugged into you harness use you wiring diagram to find this red connector.
Let me know if you want a pic.

Offline the technological J

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Re: starter motor safety unit bypass
« Reply #11 on: November 29, 2011, 01:30:51 pm »
hope he got it figured out by now...... 2 years late!

Offline Spanner 1

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Re: starter motor safety unit bypass
« Reply #12 on: November 29, 2011, 06:07:47 pm »
Toxic must be off his meds again  ::)

Offline lucky

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Re: starter motor safety unit bypass
« Reply #13 on: December 04, 2011, 10:16:26 pm »
If you unplug the SSU and remove it you can by-pass it's function by jumping the solid Green wire to the Dark Green/Red wire( there is also a light green/red ). That's it, your done........the starter will now spin whether your in gear or N or clutch is pulled or not...  N light will still work when in N 'tho...........

Solid green wire from where ? To Dark green/red wire where?
Do you mean jumping the DG wire to green wire on the plug that the starter motor safety unit was plugged into?
So what did all of this stuff in the Starter motor safety unit do?

Makes me think some electronic genius wasted a lot of time making this"safety unit"
And now they just use a clutch switch diode with clutch switch lever switch? I wish I understood all of it better.
« Last Edit: December 04, 2011, 10:27:31 pm by lucky »

Offline Toxic

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Re: starter motor safety unit bypass
« Reply #14 on: December 05, 2011, 04:11:02 am »
Here Ya go Lucky.
Here is a pic of what Spanner is describing above.





This red plug is where my SSU was plugged into.  Don't know if yours is red or white but check the wiring diagram for your bike.

Offline lucky

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Re: starter motor safety unit bypass
« Reply #15 on: December 14, 2011, 11:11:04 am »
The picture makes it very clear which wires are being jumped.
I am restoring a bike now and have a new wiring harness and I wanted to make it all a 1975 wiring plan but right handlebar switches are very hard to find.
I may have to do away with the starter motor safety switch after all.

You cannot buy them anymore so I might as well get rid of it.

Thanks for you help and patience.

BTW...What YEAR CB750 did you do this jumper wire modification on? Thanks.
« Last Edit: December 14, 2011, 11:13:24 am by lucky »

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Re: starter motor safety unit bypass
« Reply #16 on: December 14, 2011, 02:55:46 pm »
The picture makes it very clear which wires are being jumped.
I am restoring a bike now and have a new wiring harness and I wanted to make it all a 1975 wiring plan but right handlebar switches are very hard to find.
I may have to do away with the starter motor safety switch after all.

You cannot buy them anymore so I might as well get rid of it.

Thanks for you help and patience.

BTW...What YEAR CB750 did you do this jumper wire modification on? Thanks.

K3 and later (1973 onward.

Before that, ALL bikes let you hit the starter in gear if you wanted to: I still make all the bikes I build that way so it won't strand someone in a busy intersection on a hot day when the ethanol in their carbs is boiling and the bike stumbles and quits 20 feet into the intersection after a red light...You just hit the button and fireit back up instead of looking for Neutral or having to pull in the clutch (if your clutch switch still works).

Laws don't make people smarter, people do...
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Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
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Offline 1080

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Re: starter motor safety unit bypass
« Reply #17 on: December 14, 2011, 09:59:09 pm »
lucky

In the Honda 750 manual there is a schematic of the safety unit, but there is no values to the parts it requires to make one. With your unit, all the compounding removed, a person with good electronic background could repair yours.

I think the lamp filament breaks & it renders the unit useless?
« Last Edit: December 14, 2011, 10:02:09 pm by 1080 »

Offline nwrocker

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Re: starter motor safety unit bypass
« Reply #18 on: February 17, 2012, 11:41:43 pm »
When I tried this the 15 amp main fuse blew.  Dark green with red stripe to green.  The guy who had the bike before me had hot wired a switch to the two posts of the solenoid to start the bike. I am trying to figure out if I have a problem in the starter switch, neutral safety switch or in the solenoid.   Could the starter solenoid be shorted?

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Re: starter motor safety unit bypass
« Reply #19 on: August 16, 2014, 11:12:13 am »
When you unplug  the SSU you are left with a red multi pin connector, you make a jumper wire to go from the green/red to the solid green.
If you don't have the SSU plugged into you harness use you wiring diagram to find this red connector.
Let me know if you want a pic.

VERY CLEAR  Thanks!! Works perfect.
I just made up a little 3 inch jumper wire with terminals.