Hey guys, have a question about redline and top speed limiters

The Big Red One

Registered
I have a 2004LE busa with 9100 miles on it, 16/42 gearing, a full exhaust, BMC street filter, fuel programmer, marble mod, and Gregs switchable top speed de-limiter. My bike idles and runs strong and flawlessly everywhere except when I hit 10500 or abit above in 6th gear, then I hit a limiter of some type. Its geared low enough that it screams up to that rpm then hits a wall and starts lightly stuttering. I've tried switching Gregs de-limiter both ways with the same results. When I switch the de-limiter one way it changes the idle, the other way nothing is affected. But both ways it hits the same limiter at 10.5 or so like clockwork. In all the other gears it rips up to and past 11000 rpm almost quicker than I can shift. Fueling is spot on.

I'm assuming I'm hitting the top speed limiter, and that Gregs de-limiter might be faulty, but wanted some feedback from you other experienced top speeders :laugh: Greg makes an awesome product with super customer support, I'm sure if it is a faulty switch (which happens once in awhile) he'll take care of me. Just want to try and rule out hitting an early redline in 6th, or maybe the fact that I'm at 5000ft up, and a tall guy wearing a back pack might be slowing me down? It pulls crazy hard tho right up till it hits the wall and starts stuttering, so it really feels to me like its hitting a limiter of some type. I've hit the hard redline limiter before in the lower gears, and that was different than the limiter I'm hitting now. I never hit the top speed limiter with stock gearing, so I don't know where it hits and what it feels like. Any help from you pro's would be awesome :thumbsup: :beerchug:

I'd like to get it to pull to the true redline in 6th, with the 16/42 gearing and the early limiter its no fun when your buds pull away on top end. I know I still won't have stock gearing top end speed, but the extra revs I'm losing now will be all I need to keep up on the shorter high speed straights we hit :laugh:
 
sounds like the switch is bad to me...or it isnt hooked up properly. Take an ohm meter to the switch. put your probes on the two poles. Set the meter to audible. Switch the switch. if it doesnt change sounds then its a bad switch.
 
Why don't you remove the switch and use ECU editor to remove top speed limiter and raise the rev limiter a bit.
 
Regardless of what's working or not working at a point you out do the valve train and the valves will begin to float. The torque curve dies around 10.2-10.4 so why exceed that ?
Talking Gen I
 
Thanks for the info guys :beerchug: I might try and check the switch like you suggested Viper, but I have to admit I'm starting to lean towards the ecu flash I think....lots of cool things to do with that :thumbsup:
And dad, I love the pull of the 16/42 gearing, but where I live we have lots and lots of straight flat desert highways, and we end up doing a fair amount of top end blasts. With my current gearing and the 6th gear limiter, my top end is pretty much nuetered. I need more :laugh:
I wish the busa was like the 14, the 14 runs the top speed limiter off the speedo, so all you need to fool it is the new V4 speedohealer with 2 settings. One setting is for an accurate speedo, the other you set to read low, and shazaam.....limiter gone :thumbsup:
 
The limiter isnt going to affect the redline.Thats controlled in the ecu and will need to be changed via editor.To be able to gte more, then engine mods are in store but why.What is the factory gearing of the front sprocket.The rear is 42 right??
 
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