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Discussion Starter #1
I have 99 Ninja 500R. It has a vance & hines dual exhaust that the previous owner installed (separate headers coming off the engine merging into one tail pipe.)

It runs smooth in 1-3 gears at any throttle position. But in 4-6, around 6k rpm, it seems to hiccup and sputter and hesitate. Could it be the exhaust? Or is it more likely the intake?

any answers would be appreciated.
thanks
 

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I just had the same exhaust installed on my 01, and it does the same thing from about 5500-6500. No solution, but my mechanic suggested that it may be an aspect of the pipes themselves... I'm fairly certain it happens in the lower gears as well, you just don't spend enough time in that RPM range in those gears to really notice...
 

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Discussion Starter #4
I kind of figured it was probably the exhaust. Engines in bikes as well as cars rely on a certain amount of back-pressure from the exhaust. If the exhaust is too open, it can certainly cause problems. And I am sure it is way too open, judging by how loud it is.

I am thinking of getting a stock exhaust put on. I hate how this one sounds. It is just too loud, and I am tired of getting those looks from people. It actually sounds like a Harley. And I hate Harleys.

I have always been told these aftermarket exhausts hurt the power output, and now I am convinced. The first time I passed someone on a two lane road, It was a little unnerving to get hesitation from the engine while you are right next to a car in oncoming traffic!

thanks for the replies

by the way, does anyone know what the stock power and torque is of this engine? Why dont they publish power output numbers anymore?
 

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If it is seems to bog down, your engine could be starving for fuel. Talk to the tech support of the pipe you purchased, In some cases they will recommend a stage 1 or 2 jet kit. Also when the pipe was put on were the carbs adjusted? May be a small adjustment.
 

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Has the bike been properly rejetted? If not that'd explain why it runs poorly. Make sure you aren't running a stock setup on the carbs. You need a stage 1 kit for full exhaust w/ stock air intake system.
 

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Discussion Starter #7
The bike is exactly how it was when I bought it. I dont know what the guy did. He probably just had the exhaust put on and that was it, from what he told me. How much is a jet kit? I dont have the time to or know how really to install that stuff. How much would a dealer charge? If it is less than $1000, I would probably just have a dealer do it. I was thinking of taking it there anyway to have a different exhaust put on, or see if they can fix it.
 

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A jet kit usually runs 70-100 bucks, I saw a dynojet stage 1 & 3 combo on ebay last night, might wanna search for ex500 on there and see if you can still get it. A dealer should charge about $300 bucks to install a jetkit and tune the bike in. But you should be able to get a price quote from them easily enough.
 

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To install the jet kit is not difficult if you take your time, even for a novice wrench. Its a matter of loosening up the clamps that hold your carbs, disconnecting them, drain the gas from the carbs and installing the new parts. If you want some pictures I can help you with that!

Retail the kits are 85.65 for 87-04

http://www.dynojet.com/carbjet.shtml
 
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