Motorcycle Repair: YZ125 2001 Intermittent Problem, castrol tts, vacuum hose

Question
YZ125 2001 Intermittent Problem, Normally it runs fine but occasionally it bogs down with symptoms similar to fuel starvation. Have tried cleaning the fuel system from the tank down including overhauling the carby. Running Premium Unleaded and Castrol TTS synthetic. Had similar symptons on my sons last bike a CR85 but only when it was hot and found a problem in the ignition windings that only showed up on an Ohm meter when the windings were hot. With this bike it can occur even when the bike has not long been started. I have not checked the electrical system as yet, except plug changes and would appreciate any information you could supply regarding Ohm meter readings. Any other suggestions would be appreciated. Jim Whitfield.  

Answer
Hi Jim,

You're on the right track. I suspect a pinched or collapsed fuel or vacuum hose.

Also check for obstructed carb, tank, or pertcock vent obstruction.

Disassemble and clean the petcock if necessary. It varnishes, too.

I don't have specs for electrical components. Buy or borrow the service manual. Check on line for websites dedicated to the YZ.

Respectfully,
Mark Shively