Rev box yes? or no?
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With a basically stock 400ex, you will not benefit, from the use of a rev box. The engine only build power till about 6500rpm. The stock box goes to 8500(?) or something close. It will help keep it from cutting out when the wheels are in the air, but thats about it. The aftermarket rev box I had on my 400ex, made it harder to start. It was near impossible to get it running when cold outside.
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