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Bike consistently hesitates when I hit the throttle even somewhat hard. also consistently backfires on trailing throttle. 2004 24k miles, recently switched out air cleaner (every 6 months), spark plugs all 4 plugs @ 12k miles.
I've had the problem for about a year, I've lived with it since I usually don't accelerate hard, and I've learned to live with it. My guess its the fuel filter, any suggestions. When I twist throttle hard bikes moves a little faster then a second later, whamm it kicks in and away I go.

thanks,
Gene

The fuel filter is a good starting point. What RPM are you at when you crank the throttle wide open? You may be opening WOT at too low of an RPM.

When I hit the power band, around 4800 RPM, there's a very distinctive pull. However, hitting WOT prior to that RPM causes a slight hesitation prior to entering the power band.

Update: the fuel filter should be changed at 24k miles.

ProductUser

happens at almost all rpm

Could be a mixture problem. Have you tried resetting the computer?

Mine did this once and it was the fuel filter.

DJ

This may not solve your problem but it is always worth adding some injector cleaner to your fuel at least every 10,000 kls. Dirty injectors stuff up the spray pattern which is critical for instant response as well as mixture.

As part of my old workshop business I used to do well from cleaning dirty injectors with untrasonics (including for dealerships) followed by a flow test and pattern check. Unleaded fuel isn't as bad as the old leaded for fouling injectors but once dirty, unleaded contamination is harder to clean for some reason.

Typical symptoms include flat spots, hunting (surging), lousy fuel consumption (because a overly lean mixture causes you to use more throttle and therefore more fuel for the same performance) and down on power. Gas analysis is usually high on hydrocarbons and low on CO. This is because although not enough fuel is being delivered the bad spray pattern won't let it all burn. The results of cleaning is very obvious on a dyno.

Like I said - this may not be your problem but it is always worth considering.

http://www.seafoamsales.com/motorTuneUp.htm


Seafoam!

4 ounces in a full tank every half dozen + tanks of gas. It's a magic elixir that cures blah motors.

I'm leaning towards a fuel filter problem. i use techron every 6K miles

Could be a plug cap/coil failing.

I just discovered one of mine is failing - it's easy to check: simply start the bike and let it tickover, then pull the secondary plug cap off, if the bike starts to die then that particular primary plug isn't firing. To test the plug cap/coil swap the one you suspect to the other cylinder and recheck by removing that side's secondary plug. (obviously check both sides each time.)

What I also discovered is that if you pull the plug cap off, then put it back on, but not quite all the way, you'll hear the arcing between the plug cap and the spark plug. Be careful because there's enough juice in these bikes to jump a spark across at least an inch!

If you run the bike for a few seconds at a time in this situation then you won't do it any harm.

Check for air leaks at the joints on the intake side of the engine. Also, how is the valve lash? Check it.