Japanese import rpm to mph.

[run990]

I am in the process of resurrecting a japanese import vmax a 89 model.The speedometer was damaged but a virago 750 speedo had the same top speed ,the jap import has a lower top speed on the clock.
I managed to get the speedo opened and replaced the face ,I pre tensioned the needle like it was before .When I ride at 5000rpm in top gear it shows 50mph however it feels too fast going by the average traffic speed.
I saw on the Internet that the japanese model has a different final drive is this correct
Thanks

 

[Fire-medic]

I think the Japanese market bikes had some-sort of a slide extension on the top of the carb slide, to prevent its fully-opening, as a pure mechanical way of limiting top speed/RPM. Sorry I cannot offer anything on the speedo drives.

Without going out on the road, I'd think that on a USA bike, 5K rpm would be ~83 mph.

 

[sparky4123]

Canadian model would give you about 60 MPH / 100 KM/hr at 4000 rpm. Wouldn’t the Virago have a 19” front wheel which would affect the speedo gearing as well?

 

[run990]

Canadian model would give you about 60 MPH / 100 KM/hr at 4000 rpm. Wouldn’t the Virago have a 19” front wheel which would affect the speedo gearing as well?

Good thinking that man ,that may be the issue.
As a quick fix I have managed to reposition the needle so it is further up the dial.As long as when I pass speed cameras I am going slower than indicated I am happy.

 

[02GF74]

You should be able to calculate speed at given revs and gear.

Also there are gps speedometer apps that you could download to verify your speedo.

Finally you can buy a replacement speedo, more seem to be available in the US. Even with tax and import duties, it'll still work out cheaper than a speeding fine and hike in insurance due to points. It's what I did, managed to find a speedo that matched the mileage on the kmh one I had to within a few hundred miles.

 

[run990]

You should be able to calculate speed at given revs and gear.

Also there are gps speedometer apps that you could download to verify your speedo.

Finally you can buy a replacement speedo, more seem to be available in the US. Even with tax and import duties, it'll still work out cheaper than a speeding fine and hike in insurance due to points. It's what I did, managed to find a speedo that matched the mileage on the kmh one I had to within a few hundred miles.

Problem is the jap speedo has part of the restrictor system built in to it .It would mean changing the cdi and altering the wiring to suit to get round it which is a real pain

 

[MaxMidnight]

You could try a Wanted in the V Max Chat site - not that active but worth a try.
If you are happy to go aftermarket then Digital Speedo's have a fine selection.