GT500 Road Racer Project

[CJF]

It could work, but I am wondering if the lighting charge coils would provide a pulse for the tach to read?

[tz375]

The 6 pulse Polaris Tacho I have works the same way I believe. It's connected to the alternating current produced by the lighting coils. We tend to think of the pulse as if it came from a trigger so we tend to think square wave sharp cut off. I think these things just measure the sine waves from unrectified AC.

Do you know what model Polaris it came from and do you have a wiring diagram? That will tell us for sure how it should be wired and what drives it. Certainly the 6 pulse were not connected to the ignition system at all - just to the charge coils on a yellow lead.

[CJF]

That is how I was thinking about it and just couldn't figure out how the pulses would work (good thing I'm not an electrical engineer). What the heck are sine waves?

I know the tach was made for the polaris indy 500 model. Not sure of the year, but I think they made them in the 80's. I have looked all over for a wiring diagram, but haven't been able to find one yet. If you have seen it done this way already on a polaris tach, this one is likely the same.

How would I wire in the regulator? The GT500 regulator only has 2 wires (red/green and black). My guess is that I would run the red/green wire from the lighting coil to the regulator red/green wire like it is on the stock setup. Would I splice a wire off that red/green wire to the yellow tach wire? Where would I splice it from in order for the regulator to do what it needs to? Hope this makes sense!

[tz375]

I'm no sparky either, but I don't let that stop me.

The "sin wave" is the sinusoidal wave shape that alternating current makes, or rather it's the voltage graph of AC in that it reverses signs + to - each 360 degrees. So as it goes up and down it is sensed by the tacho as a pulse. It may need two coils but only one way to find out.

A Polaris voltage regulator is so simple it's amazing. It's just a zener diode mounted on a slab of alloy about 1.5" x 1/2" by 1/4". One side of the diode is connected to the power lead from the alternator (yellow) and the other side is grounded.

[CJF]

Here are few pics and a video of the "finished" bike without the fairing mounted. I got the jetting tuned in, just a slight flat spot at 1/2-3/4 throttle that I still need to work out. It is running real strong in the power band and that is without any porting, just 34MM mikuni's and racing chambers...plus a lot less weight.

There are a few small things I still need to do...or I should say redo. The master cylinder is leaking a little fluid past the seal where the lever presses the piston. Not sure yet what is going on, but It looks like one of the seals may be in wrong or something came loose. It works great otherwise especially with the race compound brake pads I have mounted. Also, the right fork leg bottom bolt is leaking a little fork oil past the copper washer, so I'll need to pull the wheel and tighten up the bolt. While I'm at it, I'm going to switch out the fork oil for a lighter oil. I have 15 weight in there now and things are a little too stiff up front. I'm hoping a lighter weight will help out. I also need to get the seat upholstered.

I've been blasting around my local roads (illegally ) and realized just how much I like riding this bike. I put a lot of time and effort into building it and I'd like to ride it more than a few track days a year. So, I'm going to make it road legal over the winter. My plan is to make the electrics so they are easily removed with an easy plug and play minimal wire loom and minimalist instruments and lighting. I still want it to look like a race bike, but be legal on the road. Plus I want it to be easy to convert back to a bare bones racer with minimal effort. I'm sure this will take a little creativity and sounds like a good winter project when there is 2 feet of snow on the ground...if it is anything like last winter.

Anyway, here are the pics and video. I'll post a few more pics later with the fairing mounted.













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[Suzukidave]

Really sharp and i really enjoy that performance 2 stroke exhaust crackle

[CJF]

Here are a few pics of the work I've been doing to make the bike street legal over the winter. I'm about 90% done with a little wiring left to do.

Made up a mounting tab for the tail light and glassed it into the bottom of the seat and purchased some brushed aluminum turn signals from LP. Still need to wire it up.


I shaved the triple tree and sanded/filled and painted to give it a cleaner look. Also, made up a mount for the Acewell tach/speedo.


Made up a mounting tab for the rear tail light switch and mounted it to the rearset bracket.


Pic shows the stainless headlight brackets I purchased and modified to shorten and pull the light closer to the forks for a better look. The turn signals are mounted off the bottom clamp using a small tab bracket.


This one shows the boyer power box mounted under the seat bracket using a small piece of aluminum and 4 screws. The turn signal relay is mounted just behind the power box. The whole thing is small and out of site.

[CJF]

I could use a little help with testing the electrics. I'm trying to test out the wiring for all the lights and speedo/tach, but can't just turn on the key and use the battery (because of the boyer box setup). I was thinking i could hook up a battery tender to the red wire or red and green wire and test out all the electrics. It didn't work. Shouldn't this work just like a battery source for power if i hook it up to the red power wire? Not sure what the red and green wire does vs the red, but I tried hooking both up and neither would allow me to power the lights. Am i missing something??

[tz375]

Looks to me like Red/Green is one end of teh charge coil going to the rectifier and Yellow/Green is teh other end and it also goes to teh rectifier. Green/white is connected to the R/G when the lights are turned on.

Red is power from the battery/rectifier to the main switch.

Orange is switched 12V from that main switch to every other circuit. Ign switch in the ON position connects Red and Orange plus it connects Brown Tail light circuit to Gray parking light.

Orange goes to the Light switch and when it's ON it connects (switched 12v) to Gray and to the dip switch. It also connects the lighting coil in teh alternator to the rectifier.

Howe much of the loom and stock switches do you have fitted?

[CJF]

I still have all the wires you mentioned and switches. The wiring change I made was to replace the regulator, rectifier and battery with the boyer box which contains the regulator/rectifier/capacitor in one. To do this, I am running the red/green and yellow/green from the lighting coils to 2 seperate yellow wires on the boyer box. I have the red (that goes to the ignition switch) and red/green wires (that goes to the left hand handlebar switch) both wired to the red wire on the the Boyer box. The black wire on the boyer box is grounded to the frame.

To test things, I the red wire that is going to the ignition switch and hooked it to the battery tender positive terminal (resulted in no lights). I also tried hooking the the red/green wire going to the left hand switch to the positive side of the batter tender (resulted in no lights). I didn't try hooking them both up to the positive battery terminal at the same time...should I? I'm a little nervous about messing things up trying too many things. I have no experience with this stuff.

Is it possible that a bad ground would prevent the lights from working with the test? Or am I trying to power it up with the wrong wires or combo of wires? I can tell you that when i try powering the lights each individually without being hooked to the harness, they work fine.

[tz375]

Try hooking 12v+ to the orange lead going into the left bar (light) switch and see if that works. You could also run a new ground from the headlight bucket to the frame and connect the headlight ground to that lead and see if that makes the lights work.

[CJF]

I think I may have found part of the problem. I found that i only have power coming out of the left hand handlebar switch for the orange and reg/green wires. Maybe my handy work rebuilding the switch a few months ago has caused the problem!! Need to take a closer look at the switch to see what might be messed up.

[tz375]

Do you have a wiring diagram that shows the switch connections?

[Suzukidave]

http://gt500.org.uk/manual1/wiringft.htm" onclick="window.open(this.href);return false;

[CJF]

http://home1.stofanet.dk/optik/suzuki/t500eldiagb.htm" onclick="window.open(this.href);return false;

thisis the wiring diagram i have been using. The wierd thing is that my ignition switch has different color wires coming out of it. Mine has Red, orange, black/yellow and black/white. The diagram I have (for a T500) shows red, orange, grey and brown. I haven't checked to see if the GT500 has a different wiring loom or at least different ignition switch than the T500, but it seems like it does. The rest of the loom looks pretty much the same as the t500 wiring diiagram. I'm going to pull the handlebar switch back apart and try again using a probe tester on the wire leads while I do it to make sure things are put back correct. Hopefully that will fix part or all of the problem.