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What application crank pulley have you used...
I'm going to make my conversion myself---or hope too! Confusedhock: ...I just love challenges, it actually looks pretty simple with supplies I have in the garage--Junk yard $30.00 alternator--and I'm off!!--Well almost, I have one question...

Anyhow, what application pulley are you folks using for the crankshaft??

Is it just another 3 groove alternator pulley from the alternator "we" are currently hanging on these bikes???--

Or if anyone knows a direct application I would appreciate it!

I would like a slighlty larger one then what is on the alternator.--I have measured pulleys from 2"-2 1/4" on the conversion alternators at the junk yard---nipo alternators---.

thanks in advance...

#1 07-23-2007, 07:52 AM,
Mine is the same size, the gentleman who designed the idea in the first place uses the same and has possibly 100,000 + K on his bike.
If your going to sit and idle the bike for a considerable time then a larger pulley or tweaking the alternator might be a choice.
The only stupid questions are the one's that are not asked.

#2 07-23-2007, 08:10 AM,
Quote:sit and idle the bike for a considerable time

For this very reason I went with a larger crank pulley to give me a 2 to 1 speed ratio.

Quote:tweaking the alternator might be a choice

You might want to check with Vic here on this. He's mentioned a special tweak to the alternator to increase the output at lower rpm's.

A source for a larger crank pulley?
Boy I wish there was. I've looked everywhere and I havent read of anyone finding one that will fit without conciderable modification.
The first pulley I used I did the modifications myself and made a sleeve adaptor to fit the crank bolt, then stacked washers as shims. While I was looking for a better way, everyone told me Mcmaster would have everything needed, I couldnt find the right combination of shim, I.D and O.D needed.
My custom pulley vibrated enough to concern me so I had one made.
If you'd like the spec's, drop me a PM with your email address and I'll send it to you.

You can check out how I did mine at <!-- m --><a class="postlink" href=""></a><!-- m -->
Mine is an 1100 but the crank is identical. You's guys with 1200's have it easier because ther's more room available behind the fairing lowers.
#3 07-23-2007, 10:39 AM,
Hello jbc,

I have an "86 SEI fuel injected bike, live in a small town with close signal lights so I wanted a pulley that would allow for charging at idle and low speeds or stop and go traffic, my main concern was ample voltage for the computer on my bike. I designed a 1 piece pulley (the same one that Dan has) and it seems to work very well. I thought about making some of these for our members but current work schedules will not allow it so I am posting my sketch for anyone to use if they desire. The pulley is based on a 4 inch 3 micro groove design with a singular stub/pulley combination. There is also a key way cut into the pulley to help keep it in position if you so desire. If you know a machinist thats' willing to help have fun.

[Image: gl1200crankpulley-copy.jpg]

Hey Dan, I checked out your site and your pulley looks identical to mine, good job and Thanks for the kind words.
1989 GL1500
#4 07-23-2007, 11:11 AM,
Hey Joe,

Do you mind if I hand this drawing out if I want?

A few people have asked for it but I wanted your blessing first.
I'm not making any money on it, just so you know.
#5 07-23-2007, 11:35 AM,
I use a 5" v-groove pulley I found on the web. At idle my system charges at 14.1 most of the time. I can dog it down to 13.5, but even at that I never have to worry about the dreaded dead battery.

I did have to space out a little more from the crank but i just used a few washers.

I've done several long rides with zero problems.
#6 07-23-2007, 11:55 AM,
Hi Dan,

Pass it out to anyone that wants it, its fine by me.
1989 GL1500
#7 07-23-2007, 12:26 PM,
Joe, I just want to say that it's really cool that you placed your drawing out here for folks to copy. You're one classy dude and a major bonus to this site. Thank you.
Ed (Vic) Belanger - 1954-2015
Founder of

#8 07-23-2007, 05:27 PM,
Joe's a great guy indeed!

It surely took a bit of effort to get those numbers right because the pulley fit's perfect. I can attest to that.
To offer that information for free is just awesome.

I'm really, really glad it does fit because I wanted the machinist to verify the measurements before cutting, but he took everything off the drawing without checking the crank like I told him!
#9 07-23-2007, 05:48 PM,
Thanks Vic I really appericate it Big Grin , but to face facts I didn't design the pulley to get rich. I designed it because I like to tinker in the shop when I have time and it helps me relax. If this can be of benifit to our fellow wingers then why should I keep this information to myself, espically since I don't have the time to make anymore right now, work has really been keeping me busy.

In the process of making a spring compressor to rebuild my 1200s air shocks in early May, my hand slipped while working with the band saw and I spent the rest of the day in the ER getting the end of my right thumb sewn back together :oops: . Even after taking precautions and years of working in a machine shop those things can still happen in an instant.

Kinda put a damper on riding for awhile but its getting back to normal now, just numb and a little touchy. Trying to use a computer was a funny sight also :lol: .

If you want to post the print as a sticky so its easy for everyone to find its OK by me.

1989 GL1500
#10 07-23-2007, 05:56 PM,
Joe, that really sucks about the injury. I was going to give you two thumbs up but since you can't signal back I won't bother so instead I'll just say thanks again and I hope you get feeling better real soon.
Ed (Vic) Belanger - 1954-2015
Founder of

#11 07-23-2007, 06:07 PM,
Hey..thanks a TON for the drawing!........

Searching a "bone yard" yesterday came up with a 4 groove pulley obviously I'll only use 3 of the grooves, many production vehicles do this already without any problems.. It was marked:

"mazda 1.8 liter"

Which model/year I dont know--it was a seperate item I found in a bin.
It was a tentioner pulley inwhich I think it will be pretty easy to make a adapter to work for the project. The diameter is 3.000 which will make for a very safe 50%+/- overdriven condition for the little alternator. I believe by starting with a pulley already, it will make the job of making the adapter much-much easier. I have a friend that offered his help with the adapter--so we'll see how it goes this weekend.

I think people may be a little worried about the RPM these alternators turn--I can only say they see 14,000-15,000 rpm's on a everyday basis at the drag strip without ever hearing any problems...these alternators are used wide-spread for drag cars/ et dragsters.

Well I'll see how this works out and get back to all of you---man would it be nice to have these pulleys available!

#12 07-24-2007, 02:19 PM,
I've pretty much disregarded the concern about turning too fast after looking at my Suburban which is a 4 to 1 ratio. 2500 rpm at 70= 10,000 rpm.
We took a trip in it to Mesa AZ, 100 mph most of the way.
It was running almost 4000 rpm, alt speed 16,000 rpm

So anyway, as for the alt on the bike, (which I have set up 2 to 1) if anything were to destruct or if a bearing went south and froze, the belt would surely break.
#13 07-24-2007, 06:04 PM,
I spoke to the manufacturer of the little Nippondenso alternator that I have on my Wing and I was told that it has a safe maximum RPM of 15,000 So if you are using a 4" crank pulley and a 2.25" alternator pulley you are in the safe zone if you are achieving the engine's redline of 7500 RPM.
Ed (Vic) Belanger - 1954-2015
Founder of

#14 07-24-2007, 08:21 PM,
Really? 15,000 rpm eh?

That's good to know!
#15 07-24-2007, 08:38 PM,

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