Fork Height Adjustments - '94+ VFR750F

by Bruce Wilson

vfr This very interesting and comprehensive article was written by Bruce Wilson who has graciously allowed me to place it here. This special article has certainly cleared up some things for me. Read and enjoy!


Background - Fork Height

The VFR's (and most m/c's for that matter) are set up to understeer by the factory at stock geometry. It is a safer way to error. An inexperienced rider does not want the m/c to turn faster than he/she is giving it input. And since many riders actually give too much initial input to set up a turn, the m/c mfg. does not want the rider to run off the inside of a corner and crash. Plus, if a bigger tire were put on the back (taller) and/or a smaller diameter tire placed on the front from the profiles of the stock and/or the diameters of stock, the bike will head towards an oversteer condition. The bike "feels" more stable with some understeer and is less affected by side winds, buffeting and operator error and stupidity or ignorance. With understeer you need to hold some pressure on the inside handlebar to hold the bike on its given line, with oversteer you have to keep pressure on the outside bar to keep the bike from falling into the corner; understeer is preferable.

Riding Characteristics of Oversteer vs Understeer

That said, it also makes the bike harder to ride on a twisty road and is a lot more fatiguing physically and mentally. I feel the ideal setup (at least for me) is setting up my VFR for _very slight_ understeer. That way, with some body english applied to the inside of the corner, the bike is dead neutral. You should be able to lock your throttle, take your set with your body (body english) and remove both hands from the bars and the bike will stay perfectly on the line you have chosen. If when doing this it wants to run wide, you have too much understeer, if it wants to tighten its line you have too much oversteer. This makes an ideal mount for me and my riding style, except if I'm packing up the Givi's, tankbag and buttpack for a long trip. Then I will generally drop the forks a couple of millimeters to add a little understeer. That way, it helps to stabilize the bike with all the stuff on it and takes less effort to hold a straight line. Only a couple of mm's up or down is needed to go from everyday sport riding bike to loaded tourer to track day demon once the forks have been setup as described above.

Hope you understand a little better what I was mentioning about understeer.

Fork Height Adjustments on a '94+ VFR750F

Stock height is 39mm, which is 1.54". It's pretty much common knowledge that they understeer at this height and raising the forks 4-6mm, even up as high as 10mm improves the handling. 5mm higher (to 44mm) would be 1.73" and 6mm (to 45mm) would be 1.77". So, if you set them at 1.75" you should be right in the acceptable zone.

A Little Adjustment Tip

Once you get a desired height, tighten the upper and lower triple clamp pinch bolts (17 ft/lbs upper, 36 ft/lbs lower) on one (1) fork leg. With the front wheel and fender off, raise the other fork higher than desired then lightly snug up the upper pinch bolt just enough that the fork is barely held in place. Using a rubber mallet (or piece of wood) tap the loose fork lightly downward with the axle in place until the axle spins very freely. You then have both forks at exactly the same height, which makes for smoother fork action.

Tighten the upper and lower pinch bolts on that fork and make sure the axle is still free spinning; if not repeat above process until it is. Reinstall the front wheel, axle, brake calipers and tighten to spec (but leave the front fender off). Without tightening the axle pinch bolts, place VFR back on the ground and pump the front end up and down _without_ using the brakes, then tighten the axle pinch bolts (16 ft/lbs). Pump the brake lever to realign the brake pads, then install and snug up the front fender. (The fender if tightened before the axle pinch bolts can slightly tweak the fork alignment, adding to stiction or "static friction").

You will be rewarded with a much more compliant fork that response to road irregularities better and therefore the bike handles better. Its worth the little extra time and you can then remove and replace your front wheel at will and everything will still be properly aligned.

Plan B - Raising the Rear Section

Then Bruce had this suggestion. There was another end to this (literally) that I should have mentioned. If the thought of raising and lowering the forks to find the neutral steering "sweet-spot" seems like an unwanted or undesirable undertaking, you can easily raise the rear ride height on the 94-97 VFR's.

The top shock mount fits into an upside down U with a bolt on the upper part, which passes through the frame and is held with a 17mm headed nut. The nut and shock mount are visible under the rear of the gas tank and with a little fiddling, you can get to the 17mm headed nut by just removing the seat, but the first time its best to lift the rear of the gas tank up a few inches and prop it up (you don't have to completely remove the tank). By loosing the 17mm headed nut, the top shock mount adapter slowly starts to back away from the frame leaving a gap. If you acquire U shaped automobile front end alignment shims, you can simply slide them into the gap created by loosening the nut. Re-tighten the nut (torque spec is 33 ft/lbs but its a self locker so torque is not that critical) and you have raised the rear ride height of your VFR.

Shims come in different thickness and one that is 2-3mm (about an 1/8th of an inch) will make a significant increase in the rear ride height. Of course, raising the rear of the bike is virtually identical to lowering the front as far as effecting steering. You don't want to go too far raising the rear as you will throw off the swingarm pivot geometry. The seat will also be farther from the ground which will definitely be a disadvantage if you have short legs or feel nervous balancing the VFR with stock seat height.

But another plus to raising the rear vs lowering the front is that you will gain ground clearance rather than loosing a little by raising the fork tubes in the triple clamps. Proper alignment of the forks is very critical and should be performed even if you don't plan to change any geometry on your VFR. But if grinding footpegs is a constant problem and you can live with a slightly higher seat, raising the ride height on the rear and leaving the forks in their (approximate) stock position will still permit you to find the ideal handling characteristics.

Bruce in Tucson '96 VFR750F


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