Rake angle can be critical. Different fork springs and rider weights can affect the dynamic angle. Like previously mentioned, a more vertical angle will make for a less stable ride at higher speeds but easier to turn at low speed. I had the same problem with my 2000 KLX300 until I put stiffer springs in the forks.

Ride on
Brewster

 

Please excuse my ignorance, but what is a front rim lock?

 

About 8" over from the valve stem is another hole for the rim lock. if it's plugged you dont have one if there is a bolt sticking out you do. It is a rubber block with a protruding bolt that pinches the tire to the rim. It keeps the tire on the rim when you get a flat. Some people counteract the wobble with spoke weights. Same as getting car tires balanced. I just removed mine had a wicked shake at 60+.

 

Yes, that was what I meant, but scrap that. I double checked it more carefully, with my son's help this time, and the distance is exactly the same, both came out to 56 3/4" center to center of the axles. The first time I measured it I didn't take enough care to make sure the wheel was dead straight, so that threw the measurements off.

 

One more thing that can cause wobble would be if the front tire is noticably cupped. It can set off a wobble, which will amplify if uncorrected. It can probably be worse if any bearings are lose or worn and/or if the forks are tweeked out of straight.

 

Could you describe what sort of "cupping" on the tire I would look for?

 

it might be worth taking it to a professional suspension shop to get the suspension adjusted for his weight...they can tell you if the bike was way off for him or not...it was only $40 in california...if it's not the suspension, they can look at the other factors...and, i'm sure a pro can give a quick look to see and recommend any other fixes...

my klx250 was way off...the guy even laughed..this was after i watched hours of youtube videos and tried to adjust the suspension myself...i was embarrassed and didn't mention i had already adjusted it myself....amazingly, after they adjusted it...the bike was completely stable well past 90 mph and i felt like i could go even faster if i could...

 

I would suspect the front tire.

Never had a wobble on the Dunlop 605's. After wearing them out it was replaced with Michelin Scorpions - very unstable at certain speed on tar. Replaced again with Bridgestone Gritty. Bit better, but still gave me a few **** tightening moments.

So, finally bought Dunlop 605 and it is rock solid.

Maybe you can swap the whole front wheel and give it a test ride?

 

This is some interesting discussion. I didn`t know 1/3 of this stuff and I am curious now. My SF is very stable at high speeds. I understand I use road tires, so I am not trying to compare my SF to a S. Nevertheless, if I nudge the bar at high speeds, the front end will wobble and then correct itself. Isn`t that a normal thing to happen? I mean, it`s a single steering pivot point. I am sure if I give it a good nudge at high speeds, I`ll end up face planted on the pavement.

 

Well, Watson. The problem seems to be when it remains harmonic. It sometimes doesn't correct itself so well.