120xr tach drops to zero around 4000rpms while driving

[chrgnu]

While picking up speed or cruising around 4000 rpms the tach will drop to zero, if i pull the throttle back alil bit the tach will jump up to the (what seems to be) correct rpm. Does anyone have any ideas what this problem may be? The engine seems to run great even when the tach falls to zero.
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[glenn property of pam]

Re: 120xr tach drops to zero around 4000rpms while driving

You may have a wire that's broke inside the insulation from being flexed over the years or a wire that's being pushed against the flywheel and shorting out.