Suzuki Burgman modification (aerodynamics + gearing mods)

[The Atomic Ass]

Originally Posted by janvos39

You are right of course on the speed of 20 Mph for full clutch engagement. Therefor I intend to shift to the second gear at approx 40 Mph outside the city.

Are you intending to go with a taller gear for the 1st gear? As in:

Old stock ratio < New 1st gear ratio < New 2nd gear ratio

OR

Old stock ratio = New 1st gear ratio < New 2nd gear ratio

I'm not sure if I read correctly, but it sounds like the former. The latter would actually allow you to get off the line better around town.

I think you might find the former uses MORE fuel in town due to having to rev the partially engaged clutch against the higher gear ratio, and also causes more clutch wear, along with very poor takeoff.

I think having a shiftable ratio for lower RPM's on the highway is a very good idea, if a massive undertaking. Please provide pics if/when you get around to working on it.

[janvos39]

Atomic,

My first new gear is actually 5% above std gearing. I expect that with riding solo on the bike (no place for a passenger) and mainly on flat roads this will not present a problem.
Std reduction of gearbox is 6.168. My new first is 5.896. The new second is 4.803.
But probably you calculated that already based on the number of teeth for the various gear wheels mentioned in a earlier post.
regards

[janvos39]

Here the pictures of the gearbox with additional gear
The changing gear mechanism is on the drawingboard. (No hardware is made yet.)

[MetroMPG]

This is getting more and more impressive.

[CobraBall]

How does it handle in crosswinds?

[The Atomic Ass]

Originally Posted by janvos39

Atomic,

My first new gear is actually 5% above std gearing. I expect that with riding solo on the bike (no place for a passenger) and mainly on flat roads this will not present a problem.
Std reduction of gearbox is 6.168. My new first is 5.896. The new second is 4.803.
But probably you calculated that already based on the number of teeth for the various gear wheels mentioned in a earlier post.
regards

Truly flat roads would certainly make it easier. It's hard to find those in my area.

Nice work on the gears, is the gear-changing mechanism going to be on the input or output side?

[janvos39]

Handling in crosswinds is comparable with an unmodified bike. Although when there is a constant crosswind the lean angle of the bike is larger probably due to the larger side surface. You get used to that.
The gear change mechanism will be on the output side. I had to shift the diskbrake some mm to make space for the shift mechanism. Still I have limited space for the shifter.

[janvos39]

It is about time to report some progress on the Suzuki Burgman project.
The project basically is twofold. Improving the aerodynamics of the Burgman and improve the engine characteristics to support good mileage.




The progress on making an additional gear is not fast, but I made some parts for the shifter. On this photo the center bar is shown that engages the two gear ratios. The banana shaped hollow part brings the movement to the outside of the gearbox. A push pull rod has to go in the aluminum housing. A cable connection then will be made to manually change the gear.
I found out in the mean time that the newest Suzuki Burgman 400 has a changed gear ratio. This is about 5% higher than older models of the 400.
So my choice for the lowest gear is now identical to this.


To improve comfort on the early morning rides to work I added covers over the handlebars. To be able to do this I had to mount the screen and the covers to the steering. By doing this I decided to give the screen a smaller angle for possible improvement of the Cd.






The last picture shows the large potential storage capacity.

[MetroMPG]

Thanks for the update, Janvos. Any new fuel economy reports?

[janvos39]

The graphical representation of the fuel used for the Burgman is put together from the quantities of each tank fill.
Since I dont have a fuel gauge this is the only way to work. I am looking at the average, which is of course also influenced by driving style , traffic conditions and weather.