Fitting a Koso or Acewell speedo. Potential problems?

[Ruby Racing]

Hi guys. This is only my second post, I have introduced myself in the correct area already so please don't shout at me.


I have done some searching but can't find the definitive answer, so maybe someone can give me lowdown.


I was planning to buy a crashed 2001 FZS600 as a project bike. Of the things I want to do is change the speedo to a Koso aftermarket unit and fit USD forks. From my searches I see that I may have BIG problems due to the speedo drive on the front wheel, the speedo and the TPS all needing to "talk" to each other in order for the bike to run correctly. If that is indeed the case has anybody managed to do away with the OE speedo and the speedo drive without encountering any running problems? If so how do you do it?


I notice the Fazer pictured at the top of this forum has USD forks and so maybe the problem can be got around? Or is that picture just a Photoshop job?


I told the seller that I'd give him an answer within the next 24 hours so would be grateful to hear from anyone who can advise me.


Thanks.

[kebab19]

The forum photo above is just a composition of all the different Fazers

I believe  owners in Japan have managed to bypassing the speedo / TPS setup, although how to do so is not common knowledge here (unless everyone keeps it to themselves).   

[Ruby Racing]

Thanks for the response Kebab19.


So does the bike run really badly if the speedo or the speedo drive is missing? Can you describe exactly what happens?

[Fazerider]

I've had the speedometer sensor pack up on me once and also made the mistake of mis-routing the cable so that passing brake bolt heads wore through the insulation and started giving me readings of about twice my actual speed. I didn't notice any change in engine performance on either occasion... though, to be fair, I was just commuting to and from work and might have missed a minor change in engine power so maybe others have noticed a difference.
What do you plan to do by way of a new sensor? If you know anyone with some electronics design skills it should be fairly straightforward to knock up a circuit to translate your new sensor pulses into something that matches what the old one produced.

[Ruby Racing]

The Koso clocks come with a sensor that reads the bolts on the disc to give a speed reading, so I'd be doing away with the OE speedo/rev counter and the speedo drive in the wheel. Hence my concern the bike will run like a bag of bolts without these items, judging by the topics I've read. Just need to know how bad it is really. The bike I'm interested in has bent forks which wasn't a great concern as I'd be fitting USD forks. However if I buy it I may need to get standard forks so that I can try and solve this riddle. An extra expense I could do without.


I really need to know what exactly happens when these two components are removed.