Here I go Again - Darksiding an 87 1200

[brianinpa]

I have always said that I will try anything once and if I like it, I'll do it again. When this dang quarantine crap has me working my tail off at my full time job but my part time job has come to an end, so I have lots of time on my hands, so I am spending a lot of overtime money and time on my bike.

When I built my 81 1200 I put a car tire on the rear of that bike and it moved it to the 87, and also the 84 Standard. All totaled, I have just a little over 17,000 miles on that tire on the three bikes and it is soon time to replace it. The only problem I have with it, is that it is an 84 wheel so I wanted to do the same to the 87 wheel.

Good grief I forgot how much it took to remove all of that bead hump...

Now... every time I thought I was close, I had to mount the tire and TRY to inflate it. It was easier years ago when I was a few years younger.

This is where I was at when I was able to finally get the tire to inflate and seat the beads. One last time mounting the tire and blow it up one last time...

Yep, I think I'll like that!

arty:

 

[Rednaxs60]

Looks good. Like the tire profile.

 

[DaveKamp]

Cool! I've been considering this for my '84 Aspy... where'd you get your tire?

 

[brianinpa]

Ordered it through Walmart. I bought two right away and only spent $104.

 

[dan filipi]

I was surprised to read under 20,000 miles from your CT. Is that all they’re getting?
I mean, I get 40-50,000 miles from my auto tires and sometimes more.

 

[brianinpa]

I think if the tire was a higher quality car tire I could get more out of it, but the tire that I have on the Standard now isn't the highest quality tire made. That one is a "Classic" All Season Radial meant for a VW. I still if I stretched it, I could get another 3,000 miles out of it. The interesting thing is that the shoulders of the tire are not showing wear that I would have expected from being on a motorcycle. Most of the wear that I have is the flat tread of the tire.

 

[pidjones]

I only get ~18000 miles out of a run flat car tire on my '06 1800. But that is more than twice what I get from a MC tire on it. We usually run soft winter compound tires on the 1800s, which could be a reason for the mileage. If I ran one of these on the front of a FWD car without rotation, I doubt I would see 30000 miles out of it.

 

[brianinpa]

pidjones » Sun Apr 26, 2020 2:01 pm[/url]":1ce5floz]
I only get ~18000 miles out of a run flat car tire on my '06 1800. But that is more than twice what I get from a MC tire on it. We usually run soft winter compound tires on the 1800s, which could be a reason for the mileage. If I ran one of these on the front of a FWD car without rotation, I doubt I would see 30000 miles out of it.

If I get 20K miles out of a rear car tire, that is 3 times the mileage out of a MT.

 

[DaveKamp]

The reason why a motorcycle tire wears in the center, is because that's where the greatest combination of contact time and force is concentrated. While I'm not afraid to lean a motorcycle, I certainly do NOT subject them to the aggressive cornering that I do on my bicycles...

But I spend most of my riding time upright, in straight lines, accellerating and stopping. My rear tires naturally develop a worn center, and substantially less wear on the sides. The handling ramifcation is obvious... when a greater lean is necessary, as I progress in lean angle, the rolling radius of the tire INCREASES (because of the ledge) and it causes the bike's rearend path to change. It feels like I'm sitting on a dirty diaper... so I replace the tire.

The part that people don't realize about car vs. motorcycle tire applications- In a turn, car tires 'tuck under'... they deflect in the OPPOSITE direction... of what a motorcycle tread does.

When you see a car tire worn in the center, it's basically because tire pressure is 'too high' for the rolling load... and the typical response is to lower the tire pressure.

You can't arbitrarily do that in a motorcycle, because standing still, the tire's SHAPE is determined by tread width, aspect ratio, and tire SHAPE... but rolling, it responds SUBSTANTIALLY to centrifugal force. In an automotive application, that force is not significant enough to impact how the tire supports the vehicle's weight, but on a motorcycle, it does a WHOLE LOT.

If you want to try a risky experiment, lower your motorcycle's rear tire pressure to about 5psi, take it out on the highway, get it up to about 75mph, and look down at the rear tire... or better yet, mount a video camera and watch what centrifugal force does... the distance from ground to rim climbs right up... and the more supple the motorcycle tire, the more centrifugal force makes it respond. On an automotive tire, that centrifugal force is very substantial, because the tire's intended shape is a flat face, and the tread belts are made with that intention. Motorcycle tires are intended to have a curved face, so they're not as supple in that plane.

 

[Ohara]

How did you remove the material from the rim? Looks like a ginder.

 

[brianinpa]

Angle grinder with a sanding wheel.

 

[DaveKamp]

Yep- that's my choice of weapon for aluminum, steel, wood, and fiberglass (but only on cold days, with a Tyvek suit on... it's itchy!)

To get a really nice result on round things, the best way is to rotate the workpiece while holding the tool steady. I have a fairly large lathe (26" swing)... I've placed wheels in the chuck, and faceplate (just depends on the wheel), and used bits of metal welded, bolted, or clamped, and for the 4" angle grinder, the side-handle hole with an appropriate size bolt, and I lock the grinder ON, but power it through a cheap motor-speed-controller (Harbor Freight), then rotate the lathe spindle at slowest speed, and gently feed the grinder in. I use this same process with die grinders to do odd bore cleanup and profile changes on cylindrical parts, I actually made a toolpost fixture for one of my die grinders because it'll reach in really deep...

But for taking that lip off, it doesn't take fancy machinery... an old pair of wood sawhorses and four deck-screws will hold the axle bolt. Have a friend rotate the wheel by hand, steadily, while you hold the grinder steady, and it'll be dusted-off in just a few rotations.

 

[Rednaxs60]

Nice friend to do all the work! :hihihi:

 

[brianinpa]

I wish I had a lathe! What I did was make a simple jig to hold the wheel and let the wheel rotate as I let my leg slow the rotation.

 

[Ohara]

Thanks for the info, when the time comes I will make a stand. Fairly new rear tires now but they won’t last long...

 

[pidjones]

To reduce the center wear and to improve ride quality, many GL1800 darksiders run at ~28-30 psi in the rear (normal MT is 40 psi) - some quite a bit lower. But they ALL recommend (since we primarily run Run Flats) that a TPMS be used. Several have reported punctures that took them to 0 psi but took many miles to become apparent.

 

[ChickenWing]

I have always said that I will try anything once and if I like it, I'll do it again. When this dang quarantine crap has me working my tail off at my full time job but my part time job has come to an end, so I have lots of time on my hands, so I am spending a lot of overtime money and time on my bike.

When I built my 81 1200 I put a car tire on the rear of that bike and it moved it to the 87, and also the 84 Standard. All totaled, I have just a little over 17,000 miles on that tire on the three bikes and it is soon time to replace it. The only problem I have with it, is that it is an 84 wheel so I wanted to do the same to the 87 wheel.

Good grief I forgot how much it took to remove all of that bead hump...

Now... every time I thought I was close, I had to mount the tire and TRY to inflate it. It was easier years ago when I was a few years younger.

This is where I was at when I was able to finally get the tire to inflate and seat the beads. One last time mounting the tire and blow it up one last time...

Yep, I think I'll like that!

arty:

 

[ChickenWing]

I have always said that I will try anything once and if I like it, I'll do it again. When this dang quarantine crap has me working my tail off at my full time job but my part time job has come to an end, so I have lots of time on my hands, so I am spending a lot of overtime money and time on my bike.

When I built my 81 1200 I put a car tire on the rear of that bike and it moved it to the 87, and also the 84 Standard. All totaled, I have just a little over 17,000 miles on that tire on the three bikes and it is soon time to replace it. The only problem I have with it, is that it is an 84 wheel so I wanted to do the same to the 87 wheel.

Good grief I forgot how much it took to remove all of that bead hump...

Now... every time I thought I was close, I had to mount the tire and TRY to inflate it. It was easier years ago when I was a few years younger.

This is where I was at when I was able to finally get the tire to inflate and seat the beads. One last time mounting the tire and blow it up one last time...

Yep, I think I'll like that!

arty:

Same type of tire I have, kinda rounded and flat for straight riding

 

[joedrum]

One THING is for sure Brian ...One of the modds ever for a 1200 ...your gig is great ...the hooch bike. Would pull the front wheel off the ground after this mod it had so much traction