BMW K bikes (Bricks)

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1Back to top Go down   Uber heated grips for < $50 Empty Uber heated grips for < $50 on Tue Apr 22, 2014 5:55 am

duck

duck
Life time member
Life time member
A few years ago for my K1100LT, I bought a small PWM (pulse width modulator) for about $19 on Fleabay to replace the HG switch on my LT. I built it into a BMW switch blank on the dash and hooked up the output not only to the heated grip elements but also to a 3mm diffused LED right above the knob so I’d know it was working and to make the knob easier to find when riding in the dark.

Uber heated grips for < $50 Varhea5

Uber heated grips for < $50 Varhea4
 
I know it doesn't sound like a huge improvement over hi/lo/off but I found it really nice to be able to dial the HGs in right where I needed them. Plus it eliminated the risk of the BMW low setting resistive wire melting its insulation off and causing a short – which had already happened to me once on that bike.
 
A little while later I was surfing Fleabay and came across a “12V 8A LED Dimmer” (it’s just a PWM) for only $3 shipped.  Having been spoiled by the variable HGs on the LT, it was a no-brainer to buy one and install it on my K1100RS.  Given the price and coming from China, I was a little skeptical about quality but I installed it a couple of years ago and it still works great.

Uber heated grips for < $50 Vhg.dimmer

Uber heated grips for < $50 Varhea3
 
Fast forward to 2014.  When I rejuvenated the K75 turbo it didn’t have heated grips so I installed some Symtecs operated with an OEM switch. Unlike the BMW setup, these have two heating elements on each side, high and low.  Although I’ve installed Symtecs on several previous Ks and had good results, this K75 has a C fairing with no hand protection from the elements so I found the high setting to somewhat lacking when it’s rather cold out.
 
I decided that the solution was to hook both high and low elements up to the output of a PWM in order to be able to get more heat out of the Symtecs but without putting both at full-time 12V which would probably be way too hot or possibly melt/warp the plastic throttle tube.
 
When you open up the $3 PWM, the controlling potentiometer on the front of it has three wires going to the PWM circuit board. As I found out when I did my K1100RS, all you need to do is lengthen those wires from the controller knob potentiometer to the circuit board and find a spot to hide the circuit board.
 
On that bike I just mounted the original box under the right knee pad vent where there’s plenty of room. On the K75 with a C faring there’s not a lot a free space so I decided to put the circuit board in a 2 3/4"  x 1 5/8" x 7/8" plastic “project box” that I could stash under the tank since it doesn't take up very much room.

Uber heated grips for < $50 Varhea7
 
I had to cut the sides of a switch blank to make the knob’s potentiometer fit in the switch blank. I covered it up with black electrical tape before I finished.

Uber heated grips for < $50 Varhea6
 
So the K75 now has not only variable heated grips but a way to get the Symtecs a little hotter when needed.  Just in time for summer….LOL.

Uber heated grips for < $50 Varhea9

If you don't like DIY projects then you can use something like a Heat-Troller instead to get variable heated grips.

The best price for the Symtecs these days is here: PowersportSuperstore.com



Last edited by duck on Wed Apr 23, 2014 5:45 pm; edited 1 time in total


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

2Back to top Go down   Uber heated grips for < $50 Empty Re: Uber heated grips for < $50 on Wed Apr 23, 2014 1:16 am

AJ.Valente

AJ.Valente
Life time member
Life time member
Yea, Duck. Great job as usual. 

On your recommendation I bought some Symtecs and found the blue/white high/low circuit was different on the Symtec drawing than from yours. I don't know if you ever noticed that.

Anywhoo, I wired the high circuit to the stock harness and left the low alone. There's a resistor in the OEM harness that works to limit the current making for two levels of heat. At the time I thought of wiring both the blue and white together in parallel as you have done, but decided against it.  I figure if the one circuit burns out I've got a spare.   :@:


__________________________________________________
'98 K1200RS Marrakesh Red

My old K100 RT Pics and Mods
    

3Back to top Go down   Uber heated grips for < $50 Empty Re: Uber heated grips for < $50 on Wed Apr 23, 2014 1:48 am

duck

duck
Life time member
Life time member
@AJ.Valente wrote:Yea, Duck. Great job as usual. 

On your recommendation I bought some Symtecs and found the blue/white high/low circuit was different on the Symtec drawing than from yours. I don't know if you ever noticed that.

Anywhoo, I wired the high circuit to the stock harness and left the low alone. There's a resistor in the OEM harness that works to limit the current making for two levels of heat. At the time I thought of wiring both the blue and white together in parallel as you have done, but decided against it.  I figure if the one circuit burns out I've got a spare.   :@:

No. My wiring is correct.  Here's how a rocker switch works: When you flip the switch down, it connects the top terminal to the center terminal. When you flip the switch up it connects the bottom terminal to the center terminal. The white wires (connected at the bottom of the switch) are for the high setting elements and the blue (connected at the top) are for the low setting.

Uber heated grips for < $50 Symtec10

The orange wire in the BMW circuit intermediate wiring harness is the resistive wire for the low setting. Since you don't need that part of the BMW wiring it is perfectly safe for you wire up the low on the Symtecs.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

4Back to top Go down   Uber heated grips for < $50 Empty Re: Uber heated grips for < $50 on Wed Apr 23, 2014 4:56 pm

AJ.Valente

AJ.Valente
Life time member
Life time member
I assumed yours was correct and that the white wire was high temp side.  Cool

Readers should note to use Duck's diagram over the Symtec if wiring from scratch.


__________________________________________________
'98 K1200RS Marrakesh Red

My old K100 RT Pics and Mods
    

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