Can 1983 Honda VT-500 Meet the Vetter Challenge?

[redyaris]

The point of no return has been reached. The suport bracket for the front body work tacked to the steering head. At this point it is only tacked in place so I can check that every thing fits. Later today it will be welded in place. getting it close to straight took some time. This is the spot normaly occupied by the headlight, horn and electrical junction box. I may have to modify the wirering harness, control cables and brake hoses, but I hope not...

[low&slow]

No risk... no reward! Looking good! Thanks for the update

[redyaris]

Had a learning experiance at the motorcycle wrecker on Thursday. I was looking for a longer tachometer cable for the Honda VT500 and discovered that every wrecked Honda motorcycle had the same two cable ends, no matter what engine it had, which made them all interchangable.

[redyaris]

Some more pics of recent slow progress. You can see the basic shape the cargo rear end will have. In a week or two I may have the side and top panels cleco'd in place.

[redyaris]

The next major problem to be solved is the airflow rate through the stock twin CV carbs. My suspision is that at 100km/h - 110km/h in 6th gear the carbs are running on the off idle cuircit, due to the low demand for power resulting from better aero and gearing. My prefered options are make an intake manifold for a single stock CV carb, or find smaller carbs at a low enough price. Some posible candidates are two CV carbs from a 600cc 4cyl sport bike.
The problem for the single CV carb option is the space available for the manifold, eather the shape is very cramped with poor flow or the carb has to be relocated further away, which would involve relocatings lots of other stuff.

[beatr911]

Redyaris, I'd stick with finishing the aero at this point. Seems that aero should produce the biggest gains anyway.

For detuning, introducing hot air would have the effect of reducing the density, therefore the amount of air entering the engine with the current carbs. I'd guess maybe only a 5% reduction though.

If you really want to change carbs and can fab up a reliable manifold, the Virago 250 carb is downdraft and small enough to suit your needs. Long manifolds could be good, especially with heated air, it allows more time for the atomized fuel to become vapor.

[redyaris]

beatr911
thanks for the suggestion I will look into the Yamaha carbs. I will finish the aero before any work on the fuel/air inlet system. The project seems be be going slower than I would wish, and may not be ready for Carmel, in which case I will bring the Suzuki GS500 and see what it can do under Vetter Conditions. I am sure of having the body work done by May, but it is the small details that seem to come out of nowere that are the stumbling block...

[redyaris]

It would apear that the Virago 250 has a single carb. which feeds both cylinders. So the idea now is to make a intake manifold for the VT500, then attach the Virago 250 single downdraft carb, but only after the aero project is finished.

The issue I am dealing with now is the conflict/interfearence between the exhaust systems large exits and the aero body work. What I have in mind is to remove the OEM two secondary "mufflers/resonators" and conect shorter/smaller exit tubes from the main central muffler, which do not interfear with the body work.

Update; I just finished removing the 3.5kg [7.7lbs] of stock exhaust parts that interfeared with the aero body work and replaced it with 0.5kg [1lb] of my home made exit tubes. so in helping the aero I have also managed to save 3kg mass.

[beatr911]

Congratulations, you just offset part of the added weight for the aero parts.

For the exhaust exit, if you are relocating it anyway, piping it to exit behind the rear tire or at the trailing edge, the exiting gasses will play a small part in filling the low pressure void thereby reducing drag. I seem to remember a picture of a faired NSU that did this. Just thought it was a neat idea.

[junkyard]

My girlfriend buell gets 70 mpg all day with no mods. It should be possible.