Inaccurate electronic tacho?

[XTlegend]

Thanks for the complement.

Maybe you will say something that will convince me otherwise - if so I will appologize profusely......

I dont know what more I can say really. I have been riding bikes continuously for nearly 30 years. I know when something isnt right. The gearing is non standard but in a way that should reduce rpm at any given speed. The tacho's reading is way too high - maybe 25%. So unless the gearbox internals have been messed about with it must be a faulty Tach. These things are just frequency to voltage converters and I believe that such circuits rely on capacitors to function correctly. So maybe there is a dry joint somewhere or whatever. Anyway, life goes on.

 

[old_chopper]

What RPM does the tach show at idle? Should be roughly 1000. What is the redline RPM on your tach?

 

[XTlegend]

What RPM does the tach show at idle? Should be roughly 1000. What is the redline RPM on your tach?

Its about 1500 at idle, and thinking about it the engine sounds as if its lower than that - I think the red line is 9500 but I'd have to check. Its a standard GSX750ES (in the UK - dont know what they called it in the US).

The thing to do would be to get one of those optical hand held rpm measuring instruments and put a spot of Tippex on the trigger end of the crank shaft.

 

[posplayr]

Maybe you will say something that will convince me otherwise - if so I will appologize profusely......

I dont know what more I can say really. I have been riding bikes continuously for nearly 30 years. I know when something isnt right. The gearing is non standard but in a way that should reduce rpm at any given speed. The tacho's reading is way too high - maybe 25%. So unless the gearbox internals have been messed about with it must be a faulty Tach. These things are just frequency to voltage converters and I believe that such circuits rely on capacitors to function correctly. So maybe there is a dry joint somewhere or whatever. Anyway, life goes on.

If you want to calculate what your tach should be reading compared to your speedometer look at this link.

http://www.robwilton.com/sprockets_gearing.html

If you want to test a tachometer, I would use a piece of test equipment. They are many types that do this like the old Dwell meter you are probably familiar with.

http://www.google.com/products/cata...log_result&ct=result&resnum=1&ved=0CB4Q8wIwAA#

maybe you will find some value in some part of the above.

If you do find you have a electronic tacho issue, the best first approach is to try and re-rejuvenate the tach by replacing potentially faulty electrolytic capacitors on the RPM board and re flowing any solder traces and joints to as well to make sure the connections are all good.

Short of that you would be looking at a replacement or a redesign of the F to V components.