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1984 vt750 clutch switch polarity ?!

370 Views 27 Replies 3 Participants Last post by  Manny13
Hello !
Just picked up my first bike landed on a 1984 vt750.
Just cleaned carbs, cleaned up some electrical had it turning over good before carbs came off but no run. (Dirty tank & carbs)
Put new bars on & unplugged the two wires off the clutch switch put cleaned carbs on but then start button was not working, thought maybe it was the unplugged clutch wires just so I randomly plugged in the wires hit the start switch & poof now no electrical what so ever… Can’t find a main fuse think someone bypassed it so battery is reading zero now (new battery)

how do I find polarity on this clutch switch is my question ?! Please I help I just wanna ride
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There is no polarity with a simple contact switch like that.
You may still have the funky factory main fuse that is a metal strip and they can deteriorate and break. See if you have this small plastic box. If so, cut it out and put in a good in-line fuse holder for the 30 amp fuse.


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And if you still have the 3 yellow wire connector they can melt so cut it out and splice it back together for a good reliable charging system.


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Frick man thanks so much I’ll dive into this tonight & update you with what I find man 🙏🏻
What would make my battery go to zero though ? I’m going to the battery shop today to get it tested …
Maybe a poor connection on the battery terminals?
Did you measure right on the posts?
If it is really 0 that will probably need a new battery .

Here is a simple test when you get it running.

Put your meter across the battery and see if at rest it is at least 12.5 volts. May need a charge first.
Then watch it while you crank it for 5-10 seconds and it should be above 9.5 to 10 volts minimum.
Then while running see if it can stay up to 13.5 to 14.5 volts as you rev it above 3000 RPM.
That will tell the basic health of the battery and charging system.
You’re the man around here for 84’s hey thanks for the help. Feel like you could get paid for this haha

What would cause a main fuse to blow seems weird that it was fine before carbs, new bars & signals went on but once I put her all back together everything worked but the starter. Once I plug in the clutch switch & try to start it ….blown fuse 🤷🏻‍

I’ll be changing that main link & trying again so I’ll pick up 10 backup fuses lol (also the battery did charge up fully)
Mine had deteriorated and cracked at one end.
Probably when I was working on something around there and broke it.
Unless you see a black scotch on the metal strip .
But all the power goes through that fuse so any short on the bars when working up there around the ignition switch could do it.
So did a sweet fix on that main fuse link thinking that’s what it is, charged my battery up put everything back together turned key on got my lights on which was exciting. Went to hit the start button & phhh everything goes black again, my main fuse isn’t blown however it took my battery to absolute zero again. All this started after putting in some aftermarket bars & turn signs that work just fine but for some reason it seems like there’s a short somewhere …. Maybe a start relay any thoughts on this in super confused & it’s embarrassing to say but I’m a red seal electrician & baffled.
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Put your meter on the battery and see when the headlight comes on if it drops many volts.
Then when you crank it and the 80 amps the starter needs probably just kills it off.
Jump with a non-running car battery, so you have the needed crank amps and see how it works.
Some guys have spent hours thinking their battery is strong when it had a weak cell.
Will do swiftly I’ll get the battery tested (still haven’t) & try a car battery in the mean time. Just get a single click then my battery goes to zero it’s so weird I had the battery in my pick up this week when I put it in the truck it was at zero 4 days later 13.4v not a on a charger just on my seat ..
A battery with a weak cell may a show good surface charge until under load.
Your starter draws about 80 amps so it is a good indicator of how strong the battery is crank amps .
Your truck starter may draw up to 150 amps, that is why car batteries are big .
So do you figure if I buy a new battery that there not way that it would short the battery out long as everything is fused properly ? Worried if I throw my truck battery on it that it might ruin it lol then I’m dead in the water lol
As soon as you touch the last cable you are installing to the battery, if there is any big spark, stop, and back up a few steps.
But that would be rare.
Make sure your new battery is the same polarity and put her in.
And that’s with the ignition key off obviously ? Just want to make sure I don’t spend $175 to just pop it with a short of some sort / potentially not have the battery shop take it back lol
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Yes key off first as you install the battery.
You might test it with the key on before you tighten the negative cable and put the negative cable on and off the post just to look for big sparks.
A smaller spark is OK since the headlight and ignition will draw power with the key on.
Just no arc welding type sparks.
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We did it swifty !! Got it idling noticed one pipe got super hot while other stayed cold for the 10min she idled & can’t touch the throttle it just falls on it’s face but I’ll try searching the forums see what I can find, thanks !!!

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Back to basics. Fuel/Air/Spark. If one cylinder is running super hot, it could be really lean, and the other starved enough for fuel that it won’t run? Try pouring a little gas into each cylinder and then see if both run for a few seconds.

That’s the plan, but you’re basically saying to take out a plug & pour gas in the colder cylinder put the plug back in see what happens? How much gas would a guy squirt in there?
My newphie mechanic says to start synching carbs & drilling/ adjusting fuel/air screws but don’t really want to start there ….
Easier to spray some carb spray into that carb or in the intake tube
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