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UPDATED INFO How I did it - Poorboy Conversion for 82 GL1100

109920 Views 285 Replies 61 Participants Last post by  CrystalPistol
This is not originally my idea, I have seen Alternators grafted onto many different vehicles over the years.

I was not happy with the limited electrical power of the stock charging system of my 82 GL1100 Aspencade. When I realized the limitations of the GL1100 charging system I went looking for ideas. I did a little searching of the internet for info, I found several references to the “poorboy” kit. I wanted to know what it looked like so that I might be able to build my own. At the time I just gathered the info I needed to build what I thought might work without keeping track of where I got the info or who’s idea it was. After all I was only going to build the one for myself.
(edited)Don “Poorboy” Pigott came up with a kit that fit the GL1200 , this kit does not work with the GL1100. Some of the info I got was from Dan Filipi over at Naked , who did this to his 83 GL1100. My thanks go out to these two men for their pioneering efforts.

It took me many hours to come up with solutions to MANY little issues. If you do this conversion yourself,even following my method you will see what I mean. This is a guide to do it yourself NOT a guaranteed Step by Step (insert legal disclaimer here).

Is it worth it? You bet it is ,I have more electrical power than I can use now. Like running the heated vest,grips,stereo,highbeam headlight,two 50 watt driving lights,two 55 watt ditch lights,cig lighter,trailer with electric cooler ALL AT THE SAME TIME!!!!

This conversion is designed to use a specific alternator,others may work. I found mine at the auto wreckers after opening several hundred hoods. The winner is a Nippondenso unit from a 1988 Pontiac Firefly Turbo 1.0 liter .

It measures 130mm or 5-1/8" from front of pulley to the rear of the unit and100mm or 4" in diameter. On the bottom of the unit the rear mounting foot is a stamped steel unit that can easily be unbolted and discarded.

No cutting required like the Geo Metro Alternator. I paid $25 and had a shop rebuild it forabout $100 he even painted it satin black before assembling it ,cheaper than one from the auto parts store.

Step one: strip the bike to this level

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Pull the timing covers off and remove the crank bolt.
Grind the grade stamp off the head of the bolt.
Chuck the crank bolt in a 1/2" drill press,spin it fast to find the center by holding a 1/8" drill bit.
Your not trying to drill the bolt yet just make a mark so you can turn it overand center punch the mark.
Now use a 1/4" bit and drill the center punch mark about 3/4" deep.Make sure the bolt is square and plumb to the bit .
Reinstall the crank bolt,reinstall the timing covers with rubber gaskets,but make a notch in the rubber where it passes over the crank bolt.
This is where you will put the pilot bit of the hole saw in the next step,you may have to remove a little of the aluminum as well.The pilot bit needs to turn freely in the hole you drilled in the end of the crank bolt and NOT catch on the timing covers at all.They will shift if it catches(ask me how I know)

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Use a 1 3/8" bimetal hole saw to cut a hole in the timing covers,medium speed light pressure works for me.use cutting fluid if you have it.

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showing the 1-3/8" hole for the new pulley perfectly centered over the end of the crank.

Notice the rubber gasket is split and pulled back out of the way for now.

That should be enough work to reward your self with a nice frosty beverage.

Now remove the covers and CLEAN up the mess you made. Metal chips (even aluminum)aren't good for the belts.Remove the drilled crank bolt and save it for when you help your buddy do his conversion.
You will need to get a longer bolt to hold the new pulley .Same thread pitch but 55mm or 60mm long. I got mine free from the local Honda dealer.
I was going to use the following drawing to have one made, but my machinist was too busy and I couldnt wait .

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I used a 2" pulley from another scrap alternator and bushed the center hole down to fit the 12mm X 60mm me a 1 to 1 drive ratio .
I would have prefered to use a 3-1/2" drive pulley but couldnt find one in time. 1 to 1 works fine but doesnt charge well under 1200RPM. I get 13.5 volts at 1300RPM.

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Here's how mine looks installed, hole in timing cover is 1.375",spacer behind pulley is 1.360"diameter.
Nice close fit to help keep the road crap out.I opened my timing covers the other day to checkfor debris,Im happy to say that after 3500km./2300miles everything is clean as a whistle in there.

Now thepart that took me the longest to get just right. when you strip the bike down to start this build you will come across the top motor mounts behind the tin heat shield in front of the carbs .
You want the left one to use as a pattern,dont forget to make the "dowels" in the new piece. Materials list: about 8 inches of 3 X 1/4 inch flat bar stock about 2 inches of 9/16 inch tube for dowels. I used a Zip disc to cut mine out

Here's the pattern


That's 5/8" up and 1-3/8" over.

time for a frosty beverage here

now its time to fit things up and butcher the tin.

New motor mount first then the heat shield tin.

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For the pivot bolt I used a 10mm X about 3-1/2". 3/8 will work but the 10mm bolt is a better fit. Iused the pivot bolt from the car I took the alternator from.
Weld bolt head to new bracket,use a spacer and nut to pull the bolt tight and square to the bracket once you establish the proper length bolt. Do not use "Allthread" rod except for the mock up stage.
Adjust spacer length so that crank pulley and Alternator pulley are perfectly in line

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another view showing clearance to the carbs

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time to butcher the tin,go slow and take little bits.The alternator needs to move a fair bit so have your belt handy,I used a Dayco Polycog #5030280 . Cut just enough tin away to allow the belt to be rolled onto the pulley.Mine could have been cut less

Dont forget to unplug the voltage regulator,this can be plugged back in to use the stock system in case of an Alternator failure/belt breakage in the middle of nowhere.

Another frosty beverage perhaps?

More tin to cut

The fan shroud needs to be trimmed. To position the rad properly I spaced the bottom out 3/4".Longer bolts needed here.Use the same rad hose but rotate it slightly to get the best fit,leave hoses off for now.

Now the part that takes a bit of fiddling...........

Modifying the fan motor support requires removing the rad andfan blade and fanmotor several times next photo shows the angle bracket I welded in after cutting out the support at the 8 o'clock position.Not the new bracket fits behind the new belt and uses the stock mounting bolt holes.

nextbit of butchering......

I had to trim theleading edge of the fan itself a little the next photo shows how much I removed to clear the new belt. I cut them off using tin snips and smoothed them with sand paper.

there seems to be no adverse effectson the ability of the fan to cool the engine. last bit of butchering to do..... The lower fairing mounts need to be cut like this and then reversed left for right because you have moved the rad bottom out 3/4". This mod solves that problem.

trim them both to look like the one on the right of the photo.File smooth and paint black.

installed they should look like this

And this

Once you put it all back together you will notice that you dont have to modify the plastic at all.It does touch the alternator but only just.

Wiring is simple There are only 2 wires I used,heavyguage from alternator output to inline blade type fuseholder and then to battery positive. I have a 40 amp fuse in mine so far it hasnt ever blown. Of the 2 wires coming out of the green plug in on the back of the alternator I used the one marked " I " or " IGN " to the ACC terminal on the fuse panel. Check your work and fire it up . You should have 13.5 volts just above idle and 14.5 above 2500RPM You now have 55amps of power to run LOTS of stuff.

Feel free to use this info for yourself or to help out a friend.

If you make some money off of it dont forget where you learned it from and make a donation to this forum.

If you make a lot of money find me.....

Enjoy, Todd

Any questions?


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Has anyone thought about running the alternator from the camshaft instead of the crank? You'd need a bigger pulley but wouldn't it eliminate a lot of clearance problems?
How strong is your camshaft drive belt?:?
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