LO206 stumbles on long straight

  • Thread starter Deleted member 21174
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Deleted member 21174

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I was looking at MyChron data from the last few practices and races. On a long (500) straight away that goes up hill about 3/4 of the way the RPM goes crazy for about .2 seconds. Always in the same spot, always the same pattern. RPM goes from 5900 to 4100, zig zags around, then back to the 5800-5900 until we hit the corner. Is this a sign the engine is going lean? If so should I replace fuel filter? fuel pump? Float valve? Check all jets especially pilot jet for clogs? Change float level to have more fuel in the bowl? Raise the rear of the float bowl slightly to keep it more on the level going uphill? Do momentary blips like this even matter - I don't see an impact on the GPS speed and the driver does not notice it - we only see RPM going haywire on the Race Studio graph.
 
It's just the rev limiter. I would bet that if you put the 7100 rpm rev limiter on it that wouldn't happen.
 
Try a smaller gear on the rear, try 2 teeth see what lap times do, then go up one tooth from there and look at lap times.
 
If you were dropping 1800 rpm your driver would notice it. Sounds like interference or cross talk in the wires. Do any of the wires run parallel to each other? Try to cross wires at 90 degrees.
 
Ok - so this may just be bad data from the tach? I can check the wires on the spark plug again. It's just weird that it's the same spot on the track over and over.
 
Bad data almost certainly. Make sure your wire is wrapped around a couple times instead of just clipped on.
 
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