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Project 900
 Nichols Motor Mount Bolts

The idea that engine mounting bolts could be a "performance modification" may at first glance seem odd.  What effect could such seemingly innocuous pieces of hardware have on how a motorcycle handles? Understanding a little about motorcycle chassis design in general, and Ducati chassis design in particular, can help us understand the theory behind the answer.

In Theory...
Back in the 'old days,' before the advent of the modern sportbike, motorcycle chassis design was more an art than a science. To many motorcycle designers the chassis -- or frame -- was merely a way of connecting a bike's many assorted parts.  The fork was connected at the front, and the swingarm (or, earlier, the rear wheel) was connected at the back.  The motor and transmission, the generator, the fuel system, etc., were supported by the middle.  Not surprisingly, then, overall rigidity was often poor. 

Did this lack of rigidity effect the motorcycle's handling?  Yes.  When, for instance, the front wheel went over a sharp bump any energy not absorbed by the suspension was transmitted to the frame.  Under this load the frame flexed, momentarily putting the front and rear wheels out of alignment. This moved the motorcycle off its line. On some machines that flex moved like a snake down the chassis to the rear, and then back up to the front, introducing a wiggle or a wobble into the bike's handling.

The author personally remembers riding a 1967 Suzuki where this motion snaked back and forth for a full second or more, making every severe bump (diagonal train crossings were the worst!) an adventure.  Indeed,  the feeling this frame oscillation produced was so "exciting" that on long, boring, stretches of highway,  he would occasionally give the handlebars a good 'tweak' just to liven things up!

Modern motorcycles -- especially high-performance sportbikes -- rarely, if ever, react quite so dramatically.  That, in part, is because their frames are truly rigid. This is certainly so for the frame on a Ducati 900SS. 

The reason the engine mounting bolts enter the picture is because the 900SS's frame is a pivotless design with the swingarm attached to the engine.  Thus, any flex or motion between the engine and the frame will make the overall chassis less than completely rigid. That, of course, would negatively effect the handling. 

In Practice...
It is to prevent that possibility that the Nichols Motor Mount Bolts were created. They are  stronger than the original bolts (heat-treated steel; nuts are titanium), and are machined to  eliminate any excessive gap between the stud, the engine, and the frame.  Because they are threaded at both ends, they can hold the engine to the frame more tightly.

In theory, then, these bolts can make a difference in how the bike handles. But, in the real world, would they make a difference for a street rider? That was the question DUC wanted to answer.

For the test we used our Project:900 mule -- a 1993 900SS, with about 35,000 miles on it's odometer.

Nichols Manufacturing provides simple step-by-step instructions for the Bolts installation.  (They say that the work can be done with hand tools in about an hour.) Since our test bike's engine was out of the frame anyway for other work, we asked the mechanic to reinstall it using the Nichol's Motor Mount Bolts.

The first rides  after installation were at a moderate pace. There was a subtle, but noticeable, change in the machine's handling, and -- particularly -- in it's feedback of the road. It felt tauter. It was also more predictable. During subsequent rides, taken at a quicker pace, these effects became more pronounced. 

The difference was really brought to my attention by that old chassis-flex bugaboo: the diagonal railroad crossing. By way of comparison, let me describe the way my old Suzuki would respond to that stimulus.

That machine would not only be sent off-course by the combination of high and low speed compression that a diagonal 'humped' crossing provided, but the induced gyrations would literally last for a few seconds. ("Wump, bam!, wiggle, wiggle, shake") 

Even completely stock the Ducati would not do that. But, as its over-damped front end went over the hard edge of the tracks the bike would be momentarily deflected, and then take, maybe, a quarter of a second to settle down. ("Bam!, wiggle.") 

With the Nichols Motor Mount Bolts installed reaction to the bump was reduced. The initial deflection was still there, but its effect was momentary. In other words, the "bam!" was still there, but no wiggle or shake followed. 

During the 500 miles entailed in this test I mostly rode on very familiar roads. Often I found myself taking note of differences -- improvements -- in the way the bike reacted to the road's various twists, turns, and bumps.

The above strongly suggests -- albeit, in a  completely subjective way -- that there was, indeed, some flex or motion between the 900SS's motor and it's frame with the stock mounting system. An examination of the  removed original bolts seems to confirm this. As seen in the accompanying photo, they show definite signs of motion-induced wear. 

In Conclusion...
The stock 900SS is a fine handling motorcycle. The Nichols Motor Mounting Bolts make it handle even better. At moderate speeds they make the bike track truer over bad pavement.  As speed picks up so does the improvement in the handling.  This -- coupled with increased rider feedback under all circumstances -- make them, in the opinion of this reviewer, a worthwhile modification. Seldom will $200 and an hour of shop time buy so much.  

-DS

Motor Mount Bolts
Part # mn2           $199.95

Nichols Manufacturing, Inc
913 Hanson Ct. Milpitas, CA
(408) 945-0911

www.nicholsmfg.com

 

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