Speedo reading less then what I am riding....

Anyone know if I can fix a speedometer that is reading slow? I went for a ride with my buddy on his brand new Yamaha Roadstar and my speedometer read 40 and he told me we were going 50 the whole time. I already changed the cable out and it did not help.

The bike is an 82 Yamaha Maxim 750.

Thanks,

Tech

 

A good clean and lube will probably fix it. The mechanical tachs and speedos tend to "gum up" and get sluggish. Everything you never wanted to know about Yamaha mechanical instrument guts: http://xjbikes.com/Forums/viewtopic/t=15303.html

 

A+ on the cleaning, just the slightest nothing in there will Gum up your day *Cough and possibly 3 speedo cables

 

thanks guys, will look at that and get right on it!!

 

what about the Gear unit at the wheel that the cable goes in to?

 

Are you running a stock sized front tire?

 

Maybe his was off. Best way to check is a GPS if you have it or access a speed trap if you can find one. Cop friend with radar/laser would work also. Many motor cycles read high (speedo faster than actual) so his might be high even brand new. When I redid mine, I had the wife check me. She said I was going 10 faster than I read. I felt like it was close (before I redid it it was always high). A check with a GPS and a speed trap showed the bike now balls on. (Explains why everyone is always passing my wife on the road!)

 

Front tire is stock size, yes. I will have my wife follow me in my little pickup and see what it reads.

 

That happened to me... turned out to be the speedometer cable.

 

I have this exact problem on the 750 I just bought. Glad to see the answer on how to fix it here. I'll start by cleaning the cable, and then go from there. I'll have to have the speedometer apart anyway, cuz the bulbs for the speedo and tach are both blown.