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GK13 10-20-2014 01:12 PM

Burgman 400
So, I'm as new to this as one can get. I've changed my oil over to fully synthetic in both the engine and final drive. I installed 19gram Dr. Pulley sliders in the cvt along with a new belt. Can't seem to find an aftermarket clutch so any suggestions? I am at 75 mpg usually. I mostly highway ride. I just put on a custom exhaust that has it way less restricted. And by doing that, it tends to smell like gasoline. I think it's dumping more gas than it need to since there's no O2 sensor for my model. Yes it's FI. I'm looking at what I can do to make it more aerodynamic to cut resistance too. Any recommendations are much appreciated.

Grant-53 10-20-2014 02:06 PM

There are some great threads here on motorcycle aerodynamics. Start by looking at for the latest developments in full body fairings. Decide if you are inclined to lean forward or backwards to lower your profile. The nose piece needs to be fairly stiff to resist the wind pressure and the bulkhead just behind the rider can be plywood or honeycomb aluminum. I like using sailplane fuselage plans to get a good shape. See or look for free sailplane plans.
The dealer's mechanics may be familiar with adjusting FI to aftermarket exhausts or they may know some tuners that race prep engines. Check with on their Powersport projects for scooters too.

GK13 10-20-2014 03:11 PM

Ok. So looks like what I want to do is streamline the front wheel. Any idea how to do this and still be able to turn the wheel? Also where it won't look too bad?

nickec 10-20-2014 03:52 PM


Originally Posted by GK13 (Post 451096)
... where it won't look too bad?

People's tastes vary. Compare these two profiles:

Which do you prefer?

Regarding ability to turn the wheel: There are three issues

1. Will your steering move unobstructed inside your fairing?
2. Will your wheel fairing interfere strike, rub, or damage your body fairing?
3. Will your wheel fairing so strongly affect air flow that balance is upset?

The first two can only be solved by measurement and trial-and-error. Consider using cardboard, zip ties, and duct tape to avoid remaking expensive parts. Once you have a good shape, transfer dimensions to your final materials.

Issue three is problematic. The size and shape, and the interaction between fairings causes great variation in balance upset. Only actual testing will tell you if your solution is viable. It seems to be true that many avoid separate fairings, opting for only a body fairing, to avoid balance upset complications. However, note that the two images above both include two fairings. The very high speeds of the two machines, and the predominant need for straight-line operation (less steering), may explain the design choices.

GK13 10-20-2014 03:59 PM

I'm really not sure what I could do to make it more aerodynamic and cut the wind better. I have a taller windshield on it already. I'm gonna try and call around about the FI adjustment.

Grant-53 10-20-2014 04:06 PM

The three issues have been addressed in several threads. The best practice for road bikes is to form a shell and cut a "smiley face" opening for the tire to move lock to lock. Vetter details this very well in chapter 54. A faired wheel needs to have its center of pressure behind the steering axis for stability. Much of the design work can be done using a half scale cardboard model.

Many of the contributors began by lowering their body position and changing the front fairing/windscreen. Next step was filling in the space behind the rider.

GK13 10-20-2014 05:01 PM

Ok. So I want no open space behind me?

Xusn96 10-20-2014 06:06 PM

looking at those two salt flat bikes and their half fairing wheels got to thinking why no one has thought of this:

or maybe they have, I envision the forward half mating in an aircraft door sort of way or simply overlapping the rear half. it's a simple crude drawing but you get the idea.

Grant-53 10-23-2014 10:23 PM

Wheel cover discs and wheel fairings can work on the front only if the center of pressure is BEHIND the steering axis to prevent wind induced steering.

Grant-53 10-25-2014 06:38 PM

Once you decide on the position of your shoulders, the rear fairing tapers down at about a 4 degree angle. The bottom angle is usually up 8-10 degrees. With a scooter your wheelbase is longer than a motorcycle (62" vs 56") and your CG is lower and further back. Make the tail as long as you feel is practical for your situation. At 30" wide, a 5:1 ratio puts your total length at 150" or 12' 6".

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