I installed a digital hourmeter/rpm gauge to my 400EX. Problem is the rpm is off by a factor of 2. Instead of 1300 rpm I get 2600 rpm at idle. Can the 400EX engine spark every revolution? Sounds crazy but I can't explain it. Please post if you know the answer.

 

yes,the 400ex sparks on every revolution .I am doing some research on finding a tach for atvs that read the right timeing. I will post what I find .

 

If this is true, a 2-cycle RPM gauge do the trick. What is Honda's reason to spark every rev?... emissions or performance? Does anybody else do this on 4-cycles?

 

all 4 strokes do this . they have a pick up coil by the flywheel that receives a signal on every rotation . they are called the fireing spark and the dead fireing spark.

 

None of my bikes do it. 91' XR250, 96' XR400, 86' 200SX..they all read right. I have the tiny tach model 4962nr* made for single cylinder 4 stokes. it does read wrong when the rev limiter kicks in.. goes from 9,000 to 5,000 RPM
Joe

 

Where did you guys get your tachs? What model? How hard was it to install? Thanks!