speed woble

ok guys. i have just recently been riding my 79 SR 750 around and just wanting to have a little fun on the straights i open her up. well i hit 70 MPH and i get a NASTY speed woble, when i put the bike back together i used the tapered roller style head bearings but i did NOT replace the wheel bearings...could this be my issue? also i have crappy shinko tires on there

i feel like its mostly tires... before i rebuilt the bike i had different tires on there and even with a pretty unhealthy motor i could hit 100 mph. i am not certain on this but i would like to be able to hit over 75 without being scared for my life

any help would be great. and wheel bearings cant be too terrible to replace

Are the steering stem bearings properly adjusted?


Has the front end (axle and triple clamps) been properly aligned and tightened?

Is there looseness in the swingarm bearings?

Are the shocks adjusted the same? Are they worn out?

Could one of the tires be suffering tread separation?

i didnt know you could adjust the steering stem bearings...

the axle and triple clamps were put on by me as carefully as i could and torqued to spec

swingarm was torqued down and greased and there is no play forward or back or side to side

the shocks... well they are stock from when i got the bike, they arent great but they are on the same setting at least.

tread seperation? i dont know this term. they were 100 bucks for the pair...a present from my parents who thought they would get me "good" tires...its the thought that counts tho right?

The factory shop manual for your model will have the correct adjusting procedure in it. As a rule of thumb, with the front wheel off the ground, the handlebars should turn easily from side to side with just enough drag that they will not flop from the center to either side. If the nut is tightened too much, the bike will have a high speed oscillation or wobble. Worn shocks and/or worn out fork oil can cause or magnify the problem.
Tread separation is when the various layers of a tire begin to come apart internally. It is often difficult to see at first, but will eventually manifest as a growing bulge.

awesome! thanks for the help, i will adjust the steering head bolt. i believe it to be a little loose, it "flops" and i thought that was good compared to the old bearings...would click and barely move!! and i belive the fork oil is in dire needs of replacement, that will happen tomorrow

next up will be shocks

I copied this from a post from Jeff Saunders(owner of Z1 enterprises)
Motorcycle Wobble Causes

There's a LONG list of potential area that can cause this.

These are not in any particular order

Wheel bearings

Steering bearings - repack grease, check tightness

Swing arm bushings/sleeves/bearings - replace is worn, repack grease

Fork springs aging - check spring length

Unequal fork oil - if seals leak, then your damping can be ineffective

Rear shocks aging, damper leaks - if you have oil leaking from the seals, the damping is toast.

Worn Tires/Mismatched tires/tire pressures/wrong size tires
Wheel alignment - don't trust the chain adjusters - I visually align the wheels.

Bent rims/broken spokes - get the wheels off the ground and spin them - check for runout / damage

Front disc warped - check for runout

Steering & swing arm bearings are very common problems, but so are tire issues (pressure/mismatch) and wheel alignment.

i will add tires out of ballance to the list. because it happened to me. :woohoo:

the rear shocks are out of adjust for your weight/style/or shot...or the settings just need playing with for me this is 99% of under load trying to go wobbles...

Lowering front end or raising rear end typically quickens the steering and thereby exacerbates any preexisting tendency to head-shake.

Stock rake and trail are more closely preserved by raising or lowering both ends an equal amount.

Good Fortune!

imo if the stuff is set up close and you feel the wrist shut off/scary wobble...it can be checked by tossing any other set of like shocks on and repeating the move that made it wiggle before...9 outta ten it can be solved with rear shocks being better set...or just plain better works the best