Sunday, September 27, 2015

Working For Insurance Is Interfering With Playing

My first step was to find out what a motorcycle tire size converts to in an auto tire size.  Found this handy site,, that tells me without any modifications to Petunia I can go up to a 18"x4.25 rim and use a 150/70-18 tire.

Petunia is the top row listed, left-right, by model, year, front size, rear size

To convert the bike tire to something useful I need to know how wide a 150 tire is.  You get that by dividing 150/25.4 = 5.9".  So, a 5.9" wide tire should fit.  I'm sure there are many who got this far and found, like I did, this converts to something like a 175R16 using the stock rim.  Therein lies the real problem, it doesn't work on a 3" rim as the suggested rim size is 5" - 5.5".  Any size below 175, that I found, is a donut spare and not usable for high milage.

So, I went to the Harley parts site I use to look into what I could do, or what might be possible.

Schematic for a 2003 rear fork assembly

 Schematic for a 2010 rear fork assembly

Seems all of the major attachment parts, connecting the rear fork to the transmission, are the exact same part numbers, so the 2010 fork would be a plug and play replacement.  But at $950 plus tax and shipping I wasn't willing to take the chance.  

Not willing to give up I searched E-bay for a few days and found a trike shop selling a 2010 take off that had less than 600 miles when it was converted. At $170 with free shipping I was willing to take the chance that this will be the answer to putting Petunia on the darkside.  It got here this week and is only 1" wider than the stock one.  Plus it came with the axel, axel nut and adjuster cam, all the bushings, and piviot shaft.  This week when I get the stock one off I will post comparison pictures.

Another reason it seemed worthwhile is I need to pull the rear fork to replace the bushings, bearings, and the drive belt.  I know the drive belt might last another 20 - 30,000 miles, but I really need to go to a 1" drive belt and pulley versus the 1.5" setup for stock 2003 and with 85,000+ on the current belt, plus with pulling the extra weight of the pig pen, I would rather do it in the comfort of my garage than calling a tow truck and going to the dealer to have it fixed. 

Rim size is also a problem. Up to 2008 Harley rims are 16" X 3" and I need a minimum rim size of 16" x 4".  Can't find anything that works, but because I have spokes I can find a 16" x 4" 40 spoke, drop center, chrome rim.  I'll order one of these bad boys and teach myself to lace and true a rim.

To be determined issues; a tire that might fit, fender clearance, using a 5" 2009-up rim with crush drive.  Adding to my already long list of wants I am adding a tubeless tire to run on my spoke rim. Might as well shoot for the moon when doing the impossible.  


  1. That's a pretty ambitions project. Going tubeless seems to be a great idea if there is a way to do it. I used to build bicycle rims all the time and it's a fun though time consuming task. I'm not sure I would try a motorcycle rim. A cast rim would also handle the side loads from the sidecar a lot better...

  2. Richard M; I agree about the cast rim, but I don't want to change all 3 of them, plus that opens a whole other can of worms. I've never even attempted truing a wheel, but the videos on the net don't seem that hard. Worst case is I get it started and then have to take it somewhere to finish the job. I've found a couple of ways to make a spoke rim tubeless and at some point will make the choice which way to go.

  3. Hey Dude have you ever swapped out a stator assembly? That job might be in my future.

    Hope you're doing well.

  4. B D Jones; I haven't yet, but it may be in my near future. Petunia eats a battery every year for the last couple of years. I need to check the regulator and stator just like you. Since I'll have the primary torn off now would be perfect timing. I don't think it is very hard now that I have the tools to tear it all down.

  5. Here's hoping the conversion works well!

  6. Charlie 6; Thanks, I just need to find some garage time. Fall break is this coming week, so I should be able to get out there and tinker. Plus the Temperature is supposed to be down in the high 80s, low 90s.