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Discussion Starter #1
In town, at speeds from I'll say 30-50mph in 3rd & 4th gear, I experience that engine thing where it is like lugging then surging. It's hard to explain. I've been told that it's a common thing, but that a Power Commander is supposed to help with it? The thing is, my bike has a PC and it still does it. I've tried experimenting with gear selection, but I don't want to have to keep the revs high all the time to overcome it. Any thoughts or suggestions?
 

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That is way too tall a gear for those speeds, especially if you have stock gearing, +2 and -1 I'm usually barely clicking into 3rd when I'm reaching 45/50mph. The rc51 engine performs pretty poorly at anything under 4,000rpms.

In town, at speeds from I'll say 30-50mph in 3rd & 4th gear, I experience that engine thing where it is like lugging then surging. It's hard to explain. I've been told that it's a common thing, but that a Power Commander is supposed to help with it? The thing is, my bike has a PC and it still does it. I've tried experimenting with gear selection, but I don't want to have to keep the revs high all the time to overcome it. Any thoughts or suggestions?
 

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My RC51 has no problem maintaining 2500 rpm all day long. I'm often below 4k rpm just to keep a low profile. There is no normal issue with driving the RC51 engine below 4k rpm. Only PC maps, etc.
 

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The rc51 engine performs pretty poorly at anything under 4,000rpms.
I disagree, the engine performs fine above 2500rpm with the correct tune. No need to rev the piss out of your engine to operate at 25mph in town. The more rpms the shorter the lifespan of the engine.

Surging and lugging are generally created from lack of fuel. If after sending the map to your bike and you still get surge, open the pc table and increase the fuel % at 2000 and 2500 rpm at 2% and 5% throttle ranges by 1 and try it. Only increase by increments of 1 until you find the sweet spot. Unless the surging is very bad then increase by increments of 2. If it gets better your headed in the right direction. Just takes a little bit of time and trial and error to get it right.
 

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I disagree, the engine performs fine above 2500rpm with the correct tune. No need to rev the piss out of your engine to operate at 25mph in town. The more rpms the shorter the lifespan of the engine.

Surging and lugging are generally created from lack of fuel. If after sending the map to your bike and you still get surge, open the pc table and increase the fuel % at 2000 and 2500 rpm at 2% and 5% throttle ranges by 1 and try it. Only increase by increments of 1 until you find the sweet spot. Unless the surging is very bad then increase by increments of 2. If it gets better your headed in the right direction. Just takes a little bit of time and trial and error to get it right.
I'll give that a shot, but aren't big twins by nature snatchy at low rpm's? And man, I do laugh a bit at the thought of cruising around on a rc51 at only 2,500rpms, wtf!? :eek:

To the OP, increasing the idle speed can also help.
 

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Discussion Starter #11
My 2 cents is here http://www.rc51forums.com/forums/showthread.php?t=17961 two threads that I feel that may have the same cause

James
Is it easy to disconnect the PC for a short period of time to test the bike without it and see if the problem goes away? And when I say easy, I mean unplugging a wire or wires under the passenger seat where the PC is, not removing the tank, etc. The thought of that makes me cringe.
 

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To bypass the PC, you need to raise the front of the tank, support it, then look near the rear of the tank, on the bike's left side for the big grey connectors. figure uot which plugs belong to the bike, and reconnect them. leave the PC plugs there to the side.
You don't have to remove the tank. But do be careful when lowering it back down so you don't pinch wires or hoses.
 

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It is kind of a pain in the ass to get to those wires. Not a huge pain, but not exactly something I would try on the side of the road.

It's way easier to just get a zero map and load that onto the PC.

Like I stated above, PC's don't magically cure problems. Getting the bike tuned will work. Getting an exhaust and a PC are only part of the equation.
 
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