85 GL1200 with motorvation formula II
Posted 9/2/2015 10:16 AM (#86078)
Subject: 85 GL1200 with motorvation formula II

New User

Posts: 4
Location: Three Rivers, MA, USA
Good morning All,
I have a 85 GL1200 with a Motorvation formula two. I am about ready to reattach the side car and was wondering what the recommended tire lead, wheel track, toe in and frame height is for this particular set up. Any advice is appreciated. Thanks in advance.
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Posted 9/2/2015 12:52 PM (#86081 - in reply to #86078)
Subject: RE: 85 GL1200 with motorvation formula II


Posts: 81
Location: south of the moon
when I was looking for almost the same info,i found all the info anyone could ever want by using the search function or read any one of the many books that are free on this site, there is not one easy or "one size fits all" answer , every rig is different, or just call motorvation. good luck

Edited by moonlite 9/2/2015 12:54 PM
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Posted 9/2/2015 5:58 PM (#86084 - in reply to #86081)
Subject: Re: 85 GL1200 with motorvation formula II

Extreme Veteran

Posts: 420
Location: Michigan - Kalamazoo
Welcome Mazz!

Here is the link to the books that Moon mentioned: http://www.sidecar.com/links3.asp

Your mileage WILL vary, but in general lead is about 10% - 20% of your tug's wheel base. Tow in the sidecar wheel between a half inch to an inch, then lean the bike out about 2-5 degrees. The books will explain the best ways to make these measurements/adjustments.
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Posted 9/2/2015 6:02 PM (#86085 - in reply to #86078)
Subject: Re: 85 GL1200 with motorvation formula II


Posts: 4833
Location: Boise, Idaho
I go one degree plus with bike and sidecar normally loaded for lean-out.

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pago cruiser
Posted 9/5/2015 12:26 PM (#86105 - in reply to #86078)
Subject: Re: 85 GL1200 with motorvation formula II


Posts: 34
Location: Tucson - its a dry heat
We've had an 84GL1200 with the same Hack for several years and maybe 40,000 miles. Its a great combo.
I use 8" lead, 6.5-7" frame height (level), 0.5-0.625" toe in. Sorry, I have the hub/wheel off the hack frame so I can't provide an accurate wheel track. But from the GL1200 rear wheel nearside rim to the outer edge of the hack frame it is 47.5". IIRC, the outside rim-rim distance was about 54". If you can wait a couple days I can verify, but we are getting ready to leave on a trip right now.

A couple comments about the rig.

1. If you have the aluminum hack wheel, it is really hard to get the wheel holes centered on the bearing hub studs. Motorvation used a "universal" 4 bolt wheel pattern, with the result that the holes are elongated to fit various wheel stud diameter patterns. And even though you can get the hack wheel balanced on a tire machine, you may still have a high speed shimmy, as the elongated holes make it it almost impossible to center the wheel EXACTLY. This problem just occurred on my 2nd Motorvation hack, currently being attached to Valkyrie. I ended up pulling the GL1200 hack hub (5 bolt) to put on the Valk. The 5 bolt hub has a chrome steel wheel with "standard" bolt holes and lug nuts.

2. Keep an eye on the alternator voltage. The alternator is a weak link in the bike. And requires pulling the engine to replace. I have read that acids in long-use, or maybe over used oil makes the alternator fail, as it is cooled by the oil sump. I have about 50k miles on our GL1200, change the oil every 2000 miles, and have a digital voltmeter installed to monitor. Have never (yet) had the problem.

3. Strongly suggest you do the 3-wire stator wire upgrade while in your garage, rather than a repair at the side of the road (assuming you are carrying the parts...). Upgrading the regulator to one from this place is a really good idea. http://www.roadstercycle.com/ I have used his mosfet regulator and wiring on a few bikes. Good quality, and gets rid of the GL1200 corrosion prone wiring connector.

4. When your handling gets weird at speed (it will), look close at the rear wheel bearing housing. Unfortunately, this part is under-designed, and will eventually fail on every GL1200 made. The bearing housing is about 1/4" aluminum, and eventually goes egg shaped, allowing the bearing to wobble. Late (84 and 85) wheel had a steel sleeve around the too thin aluminum bearing housing. The steel helps, but due to the pumpkin/wheel design, the only way to provide room for the steel sleeve is to reduce the thickness of the aluminum. If/when the now remaining aluminum hub is stressed enough (like with a sidecar), the failure (a separation of the bearing housing from the hub) will be catastrophic. The solution is to fit a GL1500 rear wheel. Not hard, but it takes maybe a day, and makes all these issues go away. There was a gent several years ago who did a little write-up that I used as a basis. Printed and scanned it a few years ago, as it took me awhile to find it. Let me know if you want a copy, and I'll try to dig it up the next couple days.

5. I found I needed the steering damper (from Motorvation) to get rid of a 20-30 mph handlebar oscillation. Problem solved.

Oh, and once you get it on the road, be careful at freeway speed. No general problems travelling 3 up (canine, wifey, youself), with travelling gear, on a good freeway. But if it's a good secondary road, and then it rapidly deteriorates to bumps and rapid undulations, the sidecart suspension can get bouncy. There is no shock on that torsion bar. If you were doing 75 in a 65, in rapid time you will need to be going 65... I have talked to Gary at Motorvation a few times on this issue, and one of his "back burner" projects is to try and fit a shock to the torsion bar.

Good luck.

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Posted 9/8/2015 10:22 AM (#86128 - in reply to #86078)
Subject: Re: 85 GL1200 with motorvation formula II

New User

Posts: 4
Location: Three Rivers, MA, USA
Thank you to everybody for the responses.
Pago I set up as you stated and it seems to be working great now. My wife is not amused at how easily we can fly the chair but she will get used to it. I think i have to play with the alignment just a bit more as i can easily tak e one hand off but if both come of she gets a hell of a tank slapper going on.
And you were right about it getting bouncy....That was fun. Have a good one all.
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Posted 10/1/2015 4:34 PM (#86370 - in reply to #86078)
Subject: Re: 85 GL1200 with motorvation formula II


Posts: 299
Location: Savannah Ga
My wife is not amused at how easily we can fly the chair but she will get used to it.

I'm surprised to hear that, I have the Motorvation II on my 1500 and I have to make a real effort to lift the car
if you don't have easy steer or raked steering you can adjust your fork tubes up in the tree some and it will make the steering easier. I moved mine about 10mm and could really tell the difference
even with that I had to add the damper to mine as well
the more air you put in the rear shock the more stable it will ride.
look at you torsion arm and see if it is the original design with the square tube or if it is the newer spline design. if it is the older one I would seriously consider sending it to Gary and let him convert it
I had the old style and it popped on me in a left hander coming off the highway, no crash but I just about needed to change my drawers
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