VF500F w/ CBR600F Tire Hugger

Hi All,

I was wondering if anyone has tackled or given some thought to removing the inner fender and fender to allow for more air flow around the engine's rear cylinder head. I've removed the fuel filter, pump and relay (went to a gravity fed system) on my '84 so I don't have much need for all the plastic in there.

I started to give this some thought after noticing that the '86 model year has additional vents added into the side panels - from this design change it looks like Honda must have started to think about ways to increase air flow for the VF500F.

With the removal of the inner fender I am considering using a tire hugger from a CBR600F as a replacement. I haven't sourced one of these but a friend has one mounted on a custom CB400F using a VF500F swingarm and it looks pretty sweet.

Any and all thoughts are appreciated!

 

I've never tried this myself. Something that stood to me about your question was that you comment about the goal being to get more airflow around the rear cylinder head. Something that I hear often misstated is that the rear cylinders run hotter than the front. While this might be true in a very precise sense, the difference in running temperature between the front and the rear is quite small. If these were air cooled engines it might be a concern, but since they have the same coolant flowing through them the temperature stays very consistent.

I think the vents were simply a cosmetic thing. I suppose we would have to track down one of the designers to know for sure!

 

flow vs temp

My thinking could be off base here so if I could ask - if the rear cylinders run a similar temperature to the front cylinders then why were the main jets on the '84 weighted with larger main's for the rear cylinders? Also, as noted in a previous post, the emulsion tubes and jet needles are different from front to rear.

Is this jetting addressing the air flow (intake/exhaust) rather than the cylinder's temperature?

Thx!

 

I put a 600F rear fender on my XX, had to widen it but for $15 on ebay it was a nice mod.

 

Ok, think about that for a while. If the rear cylinders run hotter then wouldn't they need a smaller main jet?

The reason for the different jets is not temperature, it's because front/rear the type of carb is different. One is a side draft and the other is a down draft type. I don't remember which is which, but I think the manual tells you.

As Paul Harvey would say "And now you know........ the rest of the story."

 

The emulsion tubes are different front/rear, but I think it's the jet needles that are different left/right. Explain that one! I can't.

 

carburetor design

Well noted, Thanks!

 

Front is down, rear is side.

"And now you know........ the rest of the story."

-Jake

 

jet needles

The '84 Factory Manual I have reads:


Cylinder Numbering

View attachment 10117

Carburetor Type: VD-4V Vertical & Horizontal 32mm

#1...thin needle...2VD...#105 main...#38 slow
#2...fat needle...2VA...#102 main ...#38 slow
#3...thin needle...2VD...#105 main...#38 slow
#4...fat needle....2VA...#102 main...#38 slow

Cylinder Firing Order

1-4-3-2

 

According to what you posted the needles are also the same left/right and different front/back. I'm pretty sure that's a picture of the cylinder layout and not firing order anyway.

-Jake

 

revised data

5x5, thanks!