Vt500F Gearing question for strange project

[ironpony56]

I am building a small crab boat to race in our local cheasapeake bay area town. Within the regulationss the motor has to be smaller than 600cc's, so I chose a donor bike('85 VT500F). In order to get the prop pitch correct I need help with the gearing ratios on the transmission. I have search the WWW and found no specs that break down that far. Can any one help.Ratios for 1st, 2nd, 3rd, 4th, 5th gears would be great thanks.

Rusty

[02 VFR Rider]

you can try looking on this link below and download the manual or parts catalog if it is listed
Downloadable Parts Catalogs and Service Manuals
option #2 would be going to honda and cking parts catalog.

[tinkerinWstuff]

I looked in my Clymer and can only find wear limits, not ratios. Sorry :(

The long way of it would be to simply pull the left side cover exposing the flywheel and removing the spark plugs. Shift into gear, turn the flywheel over while counting revolutions on the output sprocket (removing spark plugs to make turnover easier)

But I'll guess if you got the smarts to be worried about gear ratios and prop pitches, you've probably already considered that and are just looking for the simple answer

[ironpony56]

thanks but having no luck veiwing or accessing manuals even after i just submitted aprox. 19.00. have you tried this site before?

[MrDen]

I would call American Honda and ask if they can look up that info for you. Won't cost anything, even if they won't.

[tinkerinWstuff]

Who's word are you going to take? If the information is that hard to find, you might be better off counting revolutions yourself than trust someone over the phone to give you the right info.

[donald branscom]

Originally Posted by ironpony56

I am building a small crab boat to race in our local cheasapeake bay area town. Within the regulationss the motor has to be smaller than 600cc's, so I chose a donor bike('85 VT500F). In order to get the prop pitch correct I need help with the gearing ratios on the transmission. I have search the WWW and found no specs that break down that far. Can any one help.Ratios for 1st, 2nd, 3rd, 4th, 5th gears would be great thanks.

Rusty

I know a lot about this.
You are leaving out too many facts. Like boat hull design ,boat length etc,etc.,. First if you already have a prop just leave that part alone. It is expensive to change props. If you make the engine with a chain drive you can change sprockets easier. Almost all boat engines including out boards are 2:1 gear reduction including outboards. Most outboards top out at around 5,000 rpm. You could use the motorcycle gear box too, but once you find the right gear you probably will not shift it much . You will just adjust the throttle. I would start with 1:1 on the engine to drive shaft and use second gear on the engine. IF that seems right you will just have to make sure the engine does not get too hot from being overloaded.

You will need a fan for the engine to keep it cool. At least the motorcycle engine can make electricity to run the fan and charge a battery. You also do not want gas fumes to build up in the bilge or you can have an explosion.

I have a 19ft boat with a 5.5 HP HONDA air cooled engine. It drives a regular prop shaft. Chain drive.
The Honda engine is a 2:1 gear reduction with a centrifugal clutch. It is all hooked up and ready to go but needs the actual in the water test. The prop is an Mercury outboard prop #8 pitch about 8 inches in diameter.I used a marine grade fuel tank. Coast Guard approved.

Racing a crab boat?? hmmmmm

BTW gear ratios are listed in the specifications. You can look in a shop manual or go online.

What you are doing is a very unusual project, and many may will be able to help you.
You need to go to www.woodenboat.com/forums