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Discussion Starter #1
I've noticed that if I'm riding at slower speeds, pretty much anything less than 25mph, my bike will ride a little odd. The bike will lurch forward slightly or dive a bit, almost like I'm rocking the throttle back and forth even when keep my hand steady and driving in a straight line. I tested it in a parking lot, just letting out the clutch in first and letting the idle carry me, and it will still do it. The best I've narrowed the problem down to is that it will happen in 1st through 3rd gear under 25mph which is generally under 4k rpms for me.

The only modifications I have done to the bike is to calibrate my TPS to 1400rpm, and a M4 slip on. Not sure if that makes a difference, but I figured it would help to mention.

I'm still fairly new to bikes, and this is my first so I don't have much to compare to. It hasn't been wrecked so I ruled out damage. So is something possibly not calibrated/adjusted right, or is this just the nature of our torquey little twin and I have nothing to worry about? Or should I just scream around town at 90mph blasting knee and it'll never be an issue?
 

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Discussion Starter #3
It very well could be. I notice it a lot in parking lots or in traffic so I'm usually between 2-4k rpms when it's happening.
 

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I slip the clutch around parking lots just because of this. Hard to pull a tight, slow turn on a jerky bike.
 

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Discussion Starter #5
Slipping the clutch is the only way I found to remedy it, but I wasn't sure if I was just band aiding another problem.
 

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it was doing the same for me but on the highway(between 50-70mph), I used to crank the throttle to make it go away, when I remapped the power commander, it never happened again after and runs super smooth.

So I'm pretty positive its a problem of the fuel/air combination that is messed up and ruins your power delivery !!
Try putting bak your stock slip-on, and see if this problem goes away, if it does, then you need to configure your computer/ECU with the m4 slip-on, although a slip-on shouldnt affect this, but you never know..
btw what is tps?
I dont know what else to add... hope that helps
 

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I had an issue that seems similar - turned out that part of my chain was stretched out and it would alternately hit a slack spot in the chain and then the tight spot and feel kinda "pulsey". I finally figured this out by lifting the rear end, then put it in neutral and gave the tire a spin - it was pretty obvious when the tire wouldnt spin free. For me, an easy fix - Good Luck!
 

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Discussion Starter #8
btw what is tps?
Hmm...it might be worth putting the stock pipe back on and seeing if that changes anything, thanks.

TPS is the Throttle Position Sensor. It's generally off from the factory causing a jerkiness at slow speeds. The thread to correct it is here.

I had an issue that seems similar - turned out that part of my chain was stretched out and it would alternately hit a slack spot in the chain and then the tight spot and feel kinda "pulsey". I finally figured this out by lifting the rear end, then put it in neutral and gave the tire a spin - it was pretty obvious when the tire wouldnt spin free. For me, an easy fix - Good Luck!
I noticed my chain was doing the same thing you described a couple weeks back. I cleaned, lubed, and adjusted it hoping it would solve things but sadly it didn't. It wouldn't hurt to check it again though to make sure everything is still adjusted correctly.
 

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My money is on that chain - i adjusted mine and found the problem immediately after spinning the wheel to check for alignment - It spun free through the slack area and stopped dead at the tight spot. It took me a couple months and a trip to the dealership to find this - and no, the dealer couldnt figure it out. Sooo, do you power wheelie much???
 

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I think SVScott is right. I had the same problem with mine. My chain was totally fried and it progressively got worse despite my best efforts to pretend it wasn't there. It started with just doing it below 4k rpm then I went on a long ride one weekend and nursed it home while it did it at 80mph. Not my best motorcycle owner moment but the new chain made it ride like a dream again.
 

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Discussion Starter #11
I'll definitely check out the chain again then. I only have about 3000 miles on the bike and I bought it brand new so the chain should still be in good shape, but I'll give it another look.
 

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mine has an ugly jerky response between about 3 and 4k rpms. i have a scorp street extreme slipon and have adjusted my TPS. i think its running too lean.
 

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Discussion Starter #14
Ok so the chain does appear to be the problem, thanks for everyone who recommended that. I put it on the rear stand let it run in 1st gear at idle. Sure enough every few seconds the chain would jerk a little. I double checked my measurements from last time and the axle was still squared to the swingarm. So I loosen the axle, tighten the chain a little, double check the measurements and try it again. The chain is still jumping, although not as much as before. I've reached the point where the chain is a hair away from being too tight, but it still jumps a little.

I highly doubt my chain is fried after only 3k miles, but could it just be that the stock chain and sprockets suck so they are fried? Is there maybe a bind in it? I don't want to tighten it anymore, but it doesn't seem right for it to act like that. Any more ideas?

I really appreciate the help guys.
 

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I think you just need to replace the chain - I dont think the sprockets are part of the issue at hand, just a POS stock chain. I replaced mine and am about 3 years w/ no issues (except the "new" chain needs scrubbed and lubed this weekend as it is squeeky).
 

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i'm telling you though, with a slipon and a tps adjustment, i've heard alot of people having the jerkieness at low RPM's with part throttle. i am not going to spend 400+ bucks for a PC3 and a tune, so i dont know what to do. i think it just needs more fuel, but i'm not sure. especially since it doesnt happen on cold starts since it runs rich until it starts to warm up.....

my scorpion has a coupler that allows the stock exhaust to be put back on, and i'm thinking of trying that. but i've run it with and without the baffle and it makes no difference. same with the gipro ATRE, turned it off, no difference. premium and regular gas, snorkel in and out, still no difference. catalytic converter intact and removed, no difference. sucks.

honestly, i think the TPS adjustment is to blame. my chain is in perfect shape/adjustment, and it does it in neutral.
 

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Ok so the chain does appear to be the problem, thanks for everyone who recommended that. I put it on the rear stand let it run in 1st gear at idle. Sure enough every few seconds the chain would jerk a little. I double checked my measurements from last time and the axle was still squared to the swingarm. So I loosen the axle, tighten the chain a little, double check the measurements and try it again. The chain is still jumping, although not as much as before. I've reached the point where the chain is a hair away from being too tight, but it still jumps a little.

I highly doubt my chain is fried after only 3k miles, but could it just be that the stock chain and sprockets suck so they are fried? Is there maybe a bind in it? I don't want to tighten it anymore, but it doesn't seem right for it to act like that. Any more ideas?

I really appreciate the help guys.
Any chain is going to jump around on the rear stand idling in gear. With no load on the rear wheel you will see the power pulses jerk at the chain. No way is the chain bad at that mileage.

Follow the others advice and check the TPS.
 
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