I have a 1999 400 forman, it is turning over, but not starting, and no power to the coil? it ran until i went over a log and it bottomed out on the skid plate hard, kept running afterwards but once i turned it off, it wouldn't start., found a stray wire off the oil sensor, it's on again but still not working, could the sensor be shot??

SOURCE: Bike Died - No Power

i would check if you have a short somewhere.....but first make sure your battery connections are tight....gauges turning off and on while riding is usually a sign of a loose connection meaning you hit a bump or something and it briefly clips out...did the bike actually turn off??? i dunno....but that seems to be a very odd problem....take out the battery, put it on a trickle and let it charge to full cap....then reconnect making sure the terminal connections are secure and see what happens.... if that works, we''ll have to start diagnosing further, but like they always say, check the obvious first !

SOURCE: starting problems

Have you checked to see if there is a spark at the plugs? When you pull one of the plugs, if the plug is drenched in fuel then it is flooded. Pull each plug and dry it off as best you can. Let the cylinders air out for a while before you put the plugs back in.

SOURCE: still no spark to plugs even after replacing coils.

Either your pulse generator does not give right pulses to the ECU or your ECU need replacement.Find the wires that travel from the pulse gen to the ECU to check them for pulse.

SOURCE: 04 crf450.hard start when cold(25deg).kick for 10min.once it

1. First thing is when was the last time you had your valves adjusted
2. On cold start up twist about 15 times on your throttle, as you do that the accelerator pump in carb will shot gas in cylinder, I have a 2003 yx426 & 2005 yz450 have to do to both of them when cold out to get started

SOURCE: I have a 1997 Honda

In this bike the speedo is an electromagnetic type: a sensor sends impulsed to an conversion board that transforms them in a steady and proportional voltage that is displayed by an needle measuring electromagnetic indicator.
So only 4 things can go wrong with it - to check for them dismantle the speedo, lift the rear wheel, engage top gear and start th engine:
1 - the conversion board doesn't get powered - check for the presence of 12v at the speedo board.
2 - the sensor is dead - check for the 50mV signal coming from it to the board.
3 - the electromagnetic indicator is faulty - check the voltage on it , about 2,5V
4 - the board is dead - if the first 3 are ok then this is the cause.
If the indicator or the board are defective then the speedo is dead, replace it.