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Tach problems

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23K views 22 replies 14 participants last post by  20r100  
#1 ·
My tach has been having problems.....when the motor is on or off....the tach will jump from 0 to 7 and just bob around. between the two for a while. When the motor is on it will work sometimes then drop to zero or as it approaches 7 it will freeze at 7 and then drop to zero again.
I originally thought it was a weak battery but i changed the battery with a new one that they said was fully charged. I thought maybe the stator was not putting out enough power but i have used the battery for two weeks now and it starts everytime. So i have no idea now what the problem is. please help.
 
#2 ·
Its logging a fault look in the manual and see what the 7k fault is
 
#3 ·
If you check your manual it will be a exup fault. Mine did the same thing and the repair manual suggested to check exup wiring. For me it was a faulty exup servo motor (located beneath fuel tank). I found this by trial and error as I borrowed a servo motor from another bike and plugged it in tacho behaved normally. To verify if you have the same thing prop up the fuel tank (leave the rear pivot bolt on) so you can see the servo motor and turn the key. The servo motor should rotate. Or. Pull off the lower fairing and remove the shiny EXUP cover on the exhaust collector and turn on the key and you should see the exup valve pulley rotate. Hope it helps.
 
#5 ·
Exup problems

Thanks for the help....so i am pretty sure it is the 7k fault which is the exup. i bought the bike used and i think the guy took out the servo motor.....cuz i see the two wires for it near the clutch wire down near the pedals....so is there anyway i can fix this 7k fault if i dont even have a servo motor...i think he took the whole thing out....is there a cheap fix that i can maybe do myself?
 
#8 ·
I was reading on that sams servo replacement page that you can just do a 7.5 ohm resistor between the blk red and white red wires to solve the problem except for when the engine is on, this seems like a quick fix, do you think it would work? also where could i find these wires that go to the servo motor? is it under the tank? thanks
 
#11 ·
Repair the exup system to work as designed, your bike and you will be happier.
 
#12 ·
I jumped the wires together and it fixed the tach problem except when it first starts up and if i hold down the clutch for an extended period of time. However i really want to know, without that exup valve, does the bike lose power in lower rpms and sputter? because i changed to a full exhaust and took out that exup valve and i had the carbs synced and jetted and cleaned and it still has that problem in low rpms, is this because of the exup valve gone?
 
#13 ·
I was ridind my bike yesterday and looked down at my tac and saw it was acting wired. It will sit at 0 and then jump up to 7 sit there and drop down to norm. then do it all over again. WTF is up with that, is it a code or lose,ground wire, survo???? help me out guys. Thanks....

I pulled my tank back anf turned the key to the on postion and the servo or the exup did not move. dose this mean the servo is bad or the flap sezed shut or ???? the cables look to be tight. thanks....
 
#15 ·
I was ridind my bike yesterday and looked down at my tac and saw it was acting wired. It will sit at 0 and then jump up to 7 sit there and drop down to norm. then do it all over again. WTF is up with that, is it a code or lose,ground wire, survo???? help me out guys. Thanks....

I pulled my tank back anf turned the key to the on postion and the servo or the exup did not move. dose this mean the servo is bad or the flap sezed shut or ???? the cables look to be tight. thanks....
Try rotating the valve by hand. The EXUP valve tends to get rusty and seize up. Could just need a lube.

Mark
99 R1
 
#23 ·
i do not have the maintenence manual yet can anyone explain to me how to repair the throttle position sensor or replace it becaue my tach is jumpin from 0 to 3k and back when i have it plugged in