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A F7 sno pro was creating 138 hp @ 7800 with D&D clutch kit for F7 stock pipe. Any rpm's over 8000 resulted in a severe drop in HP. The testing was done on a Land & Sea Dyno.

My tach is reading, in digital mode, 8160. I have a F7 Sno Pro in stock form with 153 1.5" studs. To obtain the 8160 rpm reading I had to change the secondary spring to the softest setting. I have read some postings suggesting the tachs are giving false info unless the coil is flipped over. My question is am I getting false info from the sled because I have not flipped the coil or are the darn things that inaccurate? Also, What doe AC suggest for max rpm?

Any positive reply will be welcomed.
 

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What exactly do you know about this dyno test? Was the motor (coolant & pipe) up to FULL operating temperature, such as would be in real world trail riding conditions??? This is VERY important to know! -- Roy
 

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:D Yes you are getting a false reading . Get the update done A.S.A.P since there are
other issues being corrected with this campaign such as too short of bolts used to hold
the skid frame , fasteners comming undone that hold the rail caps in .
Any failure of the above could be disasterous . Without inverting the coil, the RPM
reading becomes inacurate after 7500 rpm because of the RF interferance of the
high tension wires of the coil placed too close to the wiring harness .
 
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