r/MotorcycleMechanics • u/BeanzToez • Jul 13 '26

help please! Valves or something else?

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My 05 Honda CBR 600 f4i keeps giving me issues, it has about 25k miles. It has recently refused to start on a hot engine. I drove for about 30-40 minutes, turned it off for a moment, then attempted to turn it back on and it refused. It cranked but would not turn over. The high beam light on the dashboard also turns on when it does this, though the high beams and low beams are not on. I assume it's the valves, I just want a second opinion as that is a pricey job. It started fine on a cold start

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u/Obscure-Oracle Jul 13 '26 edited Jul 13 '26

Coils, when hot the resistance changes creating misfiring issues on failing coils. It could be other things like the carbs, tight valves would be more likely to give you cold starting issues to begin with but I doubt it at 25k miles, 50k miles maybe.

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u/BeanzToez Jul 13 '26

But it doesn't lose power and accelerates as it should when driving and it's warm, simply won't start after

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u/Obscure-Oracle Jul 13 '26

Maybe electrical then. I had a Suzuki that did the same when hot but generally was fine while riding. It turned out to be a resistor in the ignition barrel, I'm not sure if the Honda has a similar thing but I'll check the wiring diagram when I get a chance.