high jumper

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westco wrote:

I finally got my '78 out of the shop and out on the road :clapper:. So far I've got 400 miles and it runs pretty well. Thanks to you who helped with the carbs and rims. :waving:. It has a couple of issues which I'm trying to get solved.

1) The front end likes to do a jumping jack thing from 25 to 35 mph. Itappears like the forks are solid and it bounces up and down on the tire.I changed fork seals during the"ressurection".I've put in the high dollar fork oil in lieu of ATF. No effect. Dropping the air pressure down to 28 psi from 36 in the front tire helped a lot butsome jumping is still there. A local mechanic suggested a GOLD valves in the forks, but at $180, they are a pretty expensive fix. The solution I'm using now is just get above 35 mph as fast as possible... cheap enough. but ignores the problem. Do any of the Guru's havean answer? There have been a couple of threads on this but it doesn't seem to have been resolved.

2) At 75 mph the Vetter gets bouncing around. The front end is solid but it appears the fairing is getting into some kind of resonance with the wind burbles. I've checked the Vetter web site, downloaded the original installation instructions and checked out the fairing. It's properly installed and is in good condition. Has anyone else experienced this situation? I'm thinking about some kind of brace. Has anyone done a brace?

How fast will these things go? I stopped at 80 mph because of the fairing and I didn't have a lot left, but I am at 4500 ft. The books say it has 78 HP, but it feels more like 60 to 70, judging from my other bikes. (runs just like an evo powered Harley)

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Gary, that bouncy front end seems to be a common problem on some early Wings.. It can be caused by heavy (too thick) fork oil, too much air pressure in the forks (if you have that option),, worn fork slider bushings,, plugged fork internal valving,, internal springs that are dragging the tube walls,, the brake anti-dive valves malfunctioning (if you have that option),, or anything that can cause stiction (sticking & releasing of the fork lower legs)..

On the other posts you read there might have been no full solution so the poster didn't respond back..

My personal 1200 went for the longest time with no front bouncing,, then it started once in a while,, then pretty regularly,, then most times below 35 MPH..

I did a fork oil change with no lasting effect,, then tried some very special slippery lube on the upper fork tubes to reduce friction (that helped a little but it was still there),, then dropped the fork air pressure to 0 & changed the fork oil to a 5W30 synthetic motor oil & the bouncing went away.

With the fork air pressure at 0 the handling was suffering so I removed the springs & made 12mm brass spring spacers that also allowed the 2 piece spring to stay centered in the tube.

At the moment I am using those spring spacers, about 2 psi of air, 5W30 Mobil 1 synthetic motor oil & the fork action is very smooth with little if any stiction in the sliding action..

Theabove has been working for a while now & about 2500 miles.. This winter I plan on pulling the forks apart & installing new slider upper bushings & new seals

On my personalbike I believemost of the problem was caused by stiction of theupper fork seals that was additionally aggravated by adding air pressure that forced the seals to grip the tubes even tighter.. Once the vehicle speed is increased above 30-40 MPH the suspension force is changed in frequency & amplitude so the stiction was (is) less of a problem there..

Not sure if the above will help you but directly but it shows what I tried & what seems to have worked for me..

On your vetter bouncing around,, look to a wheel balance problem,, then look at that fork stiction you have,, then possibly youare missing a fork dampening weight.. Not sure on your bike but some of those early Wings used a bigdampening weight inside the fairing to dampen some of that bouncing..

Twisty

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I was sure hoping to close out this thread this weekend but it just didn't happen.

1) I changed the fork oil to Mobil 1 , 5w30 synthetic. it had no effect, the GL1000 still likes to jump up and down at 30 mph.

2) I removed the springs and coated them with STP figuring that if it was stiction of the springs, it was stop as long as the STP hadn't worn off. I used to use STP as a case lub when full length resizing cartridge brass, it really reduces the friction. It had no effect.

3) I fabed two 12 mm spacers and placed on top of the springs. They had no effect either.

I got this bike from a neighbor who purchased it new in 1977. I stopped by and let him take it for a spin and he said he had never seen it do anything like that before. They sure must be touchy to something. I guess the trick is finding out what that something is.

The tires are new and were balanced,

Any other sugesstions? I see a guy had some progressive springs on EBay, but his feedback was pretty poor so I didn't bid.

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westco wrote:

I was sure hoping to close out this thread this weekend but it just didn't happen.

1) I changed the fork oil to Mobil 1 , 5w30 synthetic. it had no effect, the GL1000 still likes to jump up and down at 30 mph.

2) I removed the springs and coated them with STP figuring that if it was stiction of the springs, it was stop as long as the STP hadn't worn off. I used to use STP as a case lub when full length resizing cartridge brass, it really reduces the friction. It had no effect.

3) I fabed two 12 mm spacers and placed on top of the springs. They had no effect either.

I got this bike from a neighbor who purchased it new in 1977. I stopped by and let him take it for a spin and he said he had never seen it do anything like that before. They sure must be touchy to something. I guess the trick is finding out what that something is.

The tires are new and were balanced,

Any other sugesstions? I see a guy had some progressive springs on EBay, but his feedback was pretty poor so I didn't bid.

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Westco, was the recent fork oil you just drained out real black & gritty looking? If so leave the current oil & spacers in it & ride it for a while (find a road with bumps to force the forks to cycle a good distance).. You might have some gunk plugging the fork valve passages & it will take a while to displace that& function correctly again..

Are you running with no air in the forks?

Any scoring on the fork tubes right where the seals operate?

If it doesn't clear itself up in a short time you will probably have to pull the forks apart for inspection of the inner parts, then roll the tubes on a large flat plate glass to look for bending, & probably install new upper guide bushings..

If that bike sat fora along time in one place maybe your fronttire has a flat spot (that might cure itself with some high speed miles).. Roll the bike along real slow & look for the tire to have a flat spot as it contacts the pavement..

Twisty

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Thanks for all the feedback. To answer some of the questions, I'll fill in more detail. When the bike was brought out of retirement last month, I changed the fork seals and put a new tires on. (the old front tire was badly cupped if it means anything). Everything looked ok and the forks seemed to work. Since, I have changed the fork oil from ATF to Honda 5w fork oil to Mobil1 5w30. It has never looked dirty during changing. At around 25 to 30 mph, the forks do not slide in and out unless it hits a bump. At that speed , itbounces up and down on the front tire instead of being damped by the forks.. Near 35 mph you can see the forks start working in and out and everything is normal. No difference can be noted between the various fork oils. Stopped, I can put on the front brake and bounce up and down and the forks seem slide easily. I'm now thinking that the new seals might be just tight enough to hold things up at that frequency. I'll try running it over some rough roads and maybe try the STP on the forks around the seal area and see what happens.

I think Tony's right about the Vetter fairng. The weightcame later when Honda started making theirs. I have the Vetter Installation Manual and it doesn't mention a wieight.

I hate to say it, but it looked like snow up on the San Juan mountains this weekend. Any one planning a ride in Colorado best get a move on. Saw one riding club, probably out of Denver, with what looked to be 100 biles of all shapes and sizes heading over McClure Pass. THey were all waving and looked like they were having a great time.

Thanks to all again, Gary

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westco wrote:

Thanks for all the feedback. To answer some of the questions, I'll fill in more detail. When the bike was brought out of retirement last month, I changed the fork seals and put a new tires on. (the old front tire was badly cupped if it means anything). Everything looked ok and the forks seemed to work. Since, I have changed the fork oil from ATF to Honda 5w fork oil to Mobil1 5w30. It has never looked dirty during changing. At around 25 to 30 mph, the forks do not slide in and out unless it hits a bump. At that speed , itbounces up and down on the front tire instead of being damped by the forks.. Near 35 mph you can see the forks start working in and out and everything is normal. No difference can be noted between the various fork oils. Stopped, I can put on the front brake and bounce up and down and the forks seem slide easily. I'm now thinking that the new seals might be just tight enough to hold things up at that frequency. I'll try running it over some rough roads and maybe try the STP on the forks around the seal area and see what happens.

I think Tony's right about the Vetter fairng. The weightcame later when Honda started making theirs. I have the Vetter Installation Manual and it doesn't mention a wieight.

I hate to say it, but it looked like snow up on the San Juan mountains this weekend. Any one planning a ride in Colorado best get a move on. Saw one riding club, probably out of Denver, with what looked to be 100 biles of all shapes and sizes heading over McClure Pass. THey were all waving and looked like they were having a great time.

Thanks to all again, Gary

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Gary, careful with that STP. That stuff isn't all that slippery & can cause the seals to drag on the fork tubes.. The best would be the sperm whale oil positraction additivebut that has been replaced with a synthetic that contains a lot of sulfur so the new positraction additive is not a good choice.. What I have found best is a product called Kytrox.. It isn't available to the public as far as I know as it is poisonous..

That stiction at low speeds is not only a motorcycle problem but also an automobile problem & causes a smooth road shake at certain speeds.. Mostly caused by side load on the automobile struts.. It is the same general thing on a motorcycle as the forks sit at an angle to the load so there is great vertical load on the slider bushings that has to be overcome before they can move. Pumping the brake at low speeds induces the load in the direction they want to move so the forks move easily.. Hitting a small imperfection in the road induces the load vertical so the strut slider must not only try to move up (that increases the bushing & stiction load) but rearward & that takes a pretty good loading to move in that direction. Once in motion it should move easier as the basic stiction is overcome..

Just ride it a while & see if the low speed jouncing improves as that synthetic oil works it's way into the bushings & seal contact areas.

Twisty