Hi all,

ive been having this problem for a while now after i wash my bike.

The thing is, when i rev the bike right up it "misses" at high revs. It has to be eletrical as its just a loss of spark i think.

I washed my bike yesterday, and took the plug out to have a look at the colour (previous post), and foolishly sprayed all over with WD40 and cleaned it. put the plug in the mike ant at high revs, mising like anything. changed the plug for a new one and it was fine. Did a trial today, bike was fine. Got home and washed the bike, and its missing again . surley it cant be the plug?

any ideas guys?

max

The wash water may be making the coil leak to earth

Two systems to be concerned about. The "low" voltage side of the ignition that has the primary side of the ignition coil/kill switch/stator and the secondary side of the ignition coil/spark plug. The primary side is operating at hundreds of volts and the secondary at thousands.

The first suspect for me would be the kill switch as the stock Beta units are notoriously bad. Another suspect on the primary side would be the connectors inside of the headstock/frame junction as these are not sealed connectors and can let water in but they are unlikely to cause a short because here is quite a bit of separation between the conductors and water that is relatively pure is not that great a conductor. The only other primary side suspect is the wiring that goes to the connector that connects the stator to the CDI box. You can pull the top tank plastic piece and peek in to see if those wires have not rubbed through and check the place where they emerge by the bars to make sure there is no rub spots there as well.

On the secondary side the spark plug wire can cause problems when wet if it has any cracks or pin holes in it. This usually only occurs on very old bikes but check to see if the routing has caused any wear on the wire. The plug cap is unlikely to be an issue unless the internal resistor is broken and intermittant as there's really no place for it to short out to. It is possible to get contamination on the plug insulator that can cause high speed mifires and possibly spraying oil on the engine caused this but that is pretty unlikely as WD-40 is a pretty good insulator. Spraying it directly on the plug is probably not the best idea. If you sprayed it inside the business end of the plug that's certainly a bad idea.

As a last resort if you can't isolate the problem you can, with a dry bike, spray on what's called "conformal coating" available at do it youself type of electronics stores. Essentially this stuff is clear spray paint that has a very high dielectric strength. I'd call this a last resort though as it can be messy and is only a band aid.

Even though it dosen't relate to this problem I'll say again it's important to make sure the kill switch ground is separated from the lighting system ground as the standard grounding scheme is asking for trouble. The kill switch ground wire should be disconnected from the ground mecca at the bottom of the wireing harness and reconnected to one of the ignition coil frame lugs.

Edited February 16, 200917 yr by Dan Williams