Author Topic: 1975 CB750 K - Turn Signal Switch  (Read 2163 times)

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31rx7

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1975 CB750 K - Turn Signal Switch
« on: June 22, 2008, 05:28:06 PM »
Ever since I got my bike, the turn signals have blinked very slowly particularly at idle.  Even at higher RPM, they blink slower than it seems they should. I have switched the flasher as well as put in new bulbs and made sure the sockets are clean and such.

I found out quite by accident that if I move the turn signal thumbswitch to less than its full travel, the turn signals work fine. For example, if I push the switch to about half to 2/3 of full travel, it blinks at a good rate. So, I am thinking the left control switch with the turn signal switch, horn button, and high / low light switch has an issue and needs to be replaced. 

As an aside, the wiring is all stock and not hacked up or anything. I don't have any other electrical issues with the bike.

I haven't traced the wires from the switch yet, but am going to so I can test the various wires. 

Has anybody had something similar happen?  What was the issue? Thanks in advance.

Offline Hush

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Re: 1975 CB750 K - Turn Signal Switch
« Reply #1 on: June 22, 2008, 05:44:50 PM »
No haven't had that issue but maybe a squirt with some WD40 or CRC will flush it clean.
Taking apart either control is a nightmare only to be undertaken when fully sober or totally drunk!
If your g/f has small hands even better, alternately I'd find some decent long nosed pliers and a set of tweezers plus a couple of extremely small screw drivers.
Best done in a sound proof room or in the middle of a paddock away from sensitive ears........good luck...Hush.
I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Offline Johnie

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Re: 1975 CB750 K - Turn Signal Switch
« Reply #2 on: June 22, 2008, 06:01:44 PM »
Been there - done that - need small hands and more than 1 pair will help.  And if you do take it apart, put a white sheet on the floor so you can find the small spring and BB that will fall out more than once.  And it will fall out during tear down and rebuild.  And take pics or you may not figure out how to put those small parts back together.  And as you put it back together I found that letting gravity help you will make it easier.  Good luck if you do it...
1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA

Offline TwoTired

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Re: 1975 CB750 K - Turn Signal Switch
« Reply #3 on: June 23, 2008, 12:01:46 AM »
Replacing the bulbs is not enough.  You have to replace with the original type bulbs.  Not, the 1157, or 1156 type.  Use 1034 and 1073.

The flasher unit is load and voltage sensitive.  At idle, it will always flash slower, unless you replace with a three terminal type. (due to the alternator not making much power at idle.)

I don't advise WD40 for use on switches.  It's harmful to some plastics.  You may pay extra down the line for replacement.

The switch turns off the front run lights when it engages the turn flasher filaments.  2/3 travel likely doesn't turn off the front run lights before making the flasher filaments active.  This puts abnormal load on the flasher unit and changes the flash rate.

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline dustyc

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Re: 1975 CB750 K - Turn Signal Switch
« Reply #4 on: June 23, 2008, 12:13:04 AM »
Also, does your bike still have the turn signal beeper?  Alot of folks don't even know they're supposed to have one. 
1977 CB750

Offline Hush

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Re: 1975 CB750 K - Turn Signal Switch
« Reply #5 on: June 23, 2008, 01:06:20 AM »
A beeper ! when did bikes get those?
How the heck are we supposed to hear one of those with a crash hat on?
Or is it for the pedestrians! ;D
I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Offline TwoTired

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Re: 1975 CB750 K - Turn Signal Switch
« Reply #6 on: June 23, 2008, 01:08:50 AM »
A beeper ! when did bikes get those?
1974 models in the US.
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.