Sputters Before 3000rpm Then Fine.


05 limited ed. Motorcycle starts great runs fine but when i engage clutch it wants to sputter and die.. I have to rev about 3 grand to get it to launch.

Mechanic has had it for a year and replaced everything. When i launch and it doesnt die, it runs really rough til about 3 grand then it runs great!

When i first start it cold it runs perfectly, its only after it warms up when it does this. Tps replaced,fuel pump,new plugs ,new battery, new coils, oil change,throttle body completely taken off and send to racing company to be cleaned and diagnosed...came back nothing wrong with injectors at all...new ecu, new alternator,

It did sit outside in the rain for a bit before this happened but have had the tank drained and fresh gas put in.
Another thing i noticed before this started was I could never be able to take my key out while running and now it pulls out while running... Dont know what that affects.

Picked it up after a year still unfixed!!!! HELP!!!!!!
Im not wanting to take her to the dealership and get a rapin.


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Since you have had everything replaced I am not sure what you have going on. Maybe some of the mechanics on the board can help. I would be trying to put some seafoam through it, but from what you have done it does not sound like it would do any good.


New to forum, but not to bikes & just got my 1st Busa 2008 one month ago. It ran good but there was a hesitation from 1st to 2nd a couple of weeks ago, only one time, so I was just monitoring the incident. However, yesterday I decided to take it out on the freeway & open it up, but it couldn't get pass 6,500 rpm, so I thought there might be a rev limiter, wrong! So I decided to pull the gas tank & pull out the fuel pump & fuel filter, I was expecting slightly dirty fuel filter but it was completely clogged. The one on the left is what I pulled out & the one on the right is a new one, big difference. Replaced it & was 99.9% sure this was the issue & decided not to replace the OEM fuel pump (crossing fingers because I have only 8,700 miles).
So I rode today, although there was a lot of traffic, I was able to open it up to 9,000 rpm still pulling without any issues.
Outwardly, my bike looks perfect, however, the previous owners (2) didn't do much maintenance on the bike so I am slowly fixing issues I find. Aloha.

David Offor

The IAPS sensor controls the fuel mixture, as does the water temperature sensor, the IAPS sensor has the vacuum tube, from the 4 throttle body, vacuum tubes going to it, you didn't mention if they had been checked/changed, so I'd eliminate them if possible, also, try and see if the throttle bodies are out of sync (I'd say that's not your problem though).
It sounds like you're not getting enough fuel, after operating temperature has been reached.
I recently had misfiring on mine and found that my fuel pump was only putting out half pressure, on one of my threads I've videoed pump and injector tests.
It's a proccess of elimination, with these types of problems.

The diagram shows all the sensors, that control the mixture and emissions, ignore the red marks, its the only pic I could find on the web.
Good luck.


David Offor

I'd get involved with your TPS (throttle position sensor), if I were you, from what I've been reading, I'd suggest eliminating the TPS, sooner rather than later, the tests are quite easy, with a multimeter and workshop manual.

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