1200 Interstae slow speed wobble

[khop]

Hello all, I haven't been on in a while I decided to upgrade from my 110 naked to a newer wing Found a 1985 12 interstate (fully dressed) in nearly mint condition. Has one issue but its a scary one. A bad wobble at 20mph. Its fine at higher speeds. Tires seems pretty good maybe 60% front 80% on the back. I've researched and am looking for some feedback on the steering stem tightness. Handlebars turn all the way with front wheel off of the ground. No grinding or roughness anywhere when you turn the bars but no resistance either. I've read that the bars should stay where ever you stop them. Any comments. Look forward to hearing your input

[Whiskerfish]

It is hard to do with a dresser but bars should fall to the stop and not bounce according to the trade schools. Me personally I like them a bit tighter than that. Mike Nixon has a very good write up here http://www.motorcycleproject.com/text/shucking.html that explains a lot of what happens.

If there is any cupping at all on the front tire that will almost certainly set off a low speed wobble. Also play with the pressures.

[khop]

What would you recommend for tire pressure? I read somewhere 35 psi in the front and 37 in the back. Also what's the recommended air pressure for the suspension? Thanks. This site is awesome.

[Whiskerfish]

I do not know that bike well enough to provide a pressure recommendation with any authority. I would find out what the factory recommended and then adjust up in 2-3 psi increments to find what you like. I know on the 1000's the original factory recommendation is way out of whack for the tires of today. They recommended 28 and with the long lasting tire compounds of today you will cup out a front long before it is worn out if you run it that low. High mileage with out cupping starts above 35 for those.

[robin1731]

Suspension air pressure is dictated mostly by you and the way you ride. Solo will be different than two up. There should be a decal on the frame someplace that shows max and min pressure. Or in the owners manual if you have one. Some came with a decal affixed to the tach face. That may be gone by now though.

[Rat]

My 1200 Standard likes 38 and 40 ...... that's for Bridgestone S11 Spitfires ......

Gord (not as nice as Metzlers) Jones

[82aspy]

If your shock/fork springs are shot, even max recommended suspension air pressure may not be enuff

[gregforesi]

Fluid levels in the forks (if it has fluid) should be even. Springs front and back need to be the same length and rating.
Spin the tires and look for run-out. A bent rim will do it too.
How is the wheel balance? Take a look and see if one of the wheels might have thrown a weight off.
To my knowledge, nobody has figured out the GL1800 problem. There was a group set to sue Honda over the steering stem bearings, but all the bearings really do is keep the post in line. The wobble comes from the wheels cuz they are the only parts that rotate. You can hide the problem by tightening the bearings or adding a steering dampener.

[Easter]

Look at that front tire really carefully, maybe raise the front and spin it in the air against some kind of pointer as you would a spoke wheel to see if the tire sidewall is distorted. I have seen this with everything from bicycle tires to large semi tires.

[jdvorchak]

I have to disagree. The stem should not be so tight as to prevent free movement. There are torque specs in the factory service manual for stem tightness and it isn't that much as I remember. All of the 1200, 1500 and 1800 had a deceleration wobble usually between 45 and 25 mph. Honda denies it's a problem but every dresser 1200 I've owned had it, including my 1800. The fix was don't take both hands off the handlebars.

Now I had a 85 Aspencade that hunted at slow speeds. I guess that could be described as a wobble. The stem bearing nut was way too tight. I think the PO had tried to correct the wobble by tightening the stem nut. Back in the day the supposed fix was to tighten the bejesus out of that stem nut. I loosened the stem nut it to the proper spec and didn't take both hands off the bars between 45 and 25.

Now if your stem nut is too tight just loosen it but this time take the top off and grease the bearing. I'm sure any grease in there is solid as a rock and long since quit providing lubrication. While on the center stand jack the front wheel off the ground just far enough to expose the lower bearing and grease it too. Let the wheel down to get the top bearing and nut on then use the FSM method for torqueing. Oh if you don't have the special socket don't worry. A pair of slip joint pliers works and all we're talking is about is tight enough to remove any free play but not so tight as to cause the bearing to bind. If you're every replaced a wheel bearing on a car it's the same principal. Tighten the nut down good and hard, to get the bearing to seat, then back it off and tighten only enough to remove free play.

[jdvorchak]

Oh and gregforesi is probably correct that it is related to the tires. My 1800 would stop the wobble, after a tire change, for about 7k miles then it was back. I've even heard some folks say it's really the back tire causing it. Everything I've read, and there are as many theories as bikes that wobble, seem to be plausible fixes. None have proven to be a solid fix. Some folk have spent literally thousands of dollars on traxion or Progressive or well you name it. They all claim to fix it and most guys, who have just spent $2000 getting the front end rebuild swear it fixed it. Of course they are going to say that. They just spent $2000 on snake oil!

Me? I'm cheap.. I just kept both hands on the bars when decelerating through 40mph... Of course then I traded the 1800, after suffering for 7 years on it, for a Harley and never looked back.

[Whiskerfish]

Slowing in the 35-40 mph range with hands off is also where it usually shows up on the 1000's. The high speed Weave I have only experienced when cornering with neutral or less throttle in the 80-90 mph range and just guessing but I think that is frame flex related. Might be back tire or swing arm related but those have been checked/fixed/changed and it is still repeatable. I have never had a serious High speed Wobble on a wing yet. Knock on wood!!

[rcmatt007]

I recall BMW's having a hand tightner on the stem to be a dampner against wobble.... first I would check everything everyone suggested, but then again, many bikes have a slight wobble

now put a sidecar on a bike and REALLY experience wobble (what is it 30 seems to be the speed) especially on slowing down

[sunnbobb]

check the torque on the swingarm bearing nuts