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Discussion Starter #1
stock pipes to after market pipes...what are the common issues with the bike's performance? I'm new here and I just picked up a 92' ex500 w/ 30k miles and it came with a 2:1 yoshi pipe. The bike idles good and pulls strong up to 80mph then the speedometer needle just stop climbing. In fact if I open the throttle all the way, the needle actually drops down to the 70's. However, when I hold the throttle open at 90%, the needle very slowly crawl towards 90mph. Do you think it may need re-jetting? Where is the air/fuel mixture screw located?

Any feedback is appreciated!
 

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It sounds like your carbs need cleaning. Your main jet is probably clogged with crap.
 

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Discussion Starter #4
Not sure if the bike has a fuel filter but it starts right up hot/cold, idles well, no hesitation and pulls strong or normal for this bike but the speedometer just seem to stop or very gradually climb after 80mph. This is a new bike for me and it doesn't come w/ any manual so I can't even trouble shoot it via the manual. I just thought that it's strange for a bike like this to ride smoothly and pull strongly until 80mph and then stops pulling. Anyone still have their stock pipes and want to give it up? I would like to go back to stock to see if it cures the issue or not...I'll pay for shipping.

Thanks for the feedback!
 

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If you just rip the throttle, from idle to wide open in neutral, does it choke and sputter? Does running with the choke on make it better/worse?

I keep leaning toward the idea that a previous owner may have overjetted it and it's running too rich at WOT, but I'm not sure of anything.
 

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Discussion Starter #7
Hey Nick,

those things are fairly easy to try and I'll try it but will running with the choke on at freeway speeds damage the bike or flood the fuel system?
 

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It will help building carbon residue in the chamber, eventually you'll have to replace the spark plugs..
 

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I'm pretty sure this is the case (I'm only not sure if our bike uses more fuel or less air).

Old school: the choke allows less air through - bike runs richer.
Newer tech: it's a fuel enrichment circuit that adds fuel to the mix - bike runs richer.

Either way, all you're doing is using a touch more fuel per cfm of air. I just wanted you to try it to see if it made a difference. If you turn it on and the bike does the same thing but worse I'd think you're set too rich. If you turn it on and the bike acts a little better then you're probably on the lean side. It just came to mind because it's how I finally figured out that the problem with my KZ was that the needles were too low and the engine was starving.

It won't hurt your bike, especially not short term for testing purposes. Even the idea of carbon residue only applies to a properly tuned bike driven with the choke on unnecessarily. If the bike is in running rich you're going to get residue anyway, and if it's running super-lean then you might burn up and or melt parts.
 

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Discussion Starter #10
Hey guys, I put a bottle of techron fuel cleaner in the tank and it seems to run better. I might not need the pipes but we'll see.

Thanks for all the feedbacks!
 

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Are you looking for pipes because you want to go back stock, or just to see if it fixes it? If it's just to try and then go back to aftermarket then I'd just recommend saving your time and money. There are so many bikes running aftermarket exhaust that it's obvious that it's possible, it's just a matter of tuning yours to match.

If you're worried about tearing into the carbs, don't be. There are enough how-tos and helpful people on the forum that you can find plenty of help getting things lined out. Back shortly after I got my KZ I sent the carbs to a local guy because they were dumping gas and needed a rebuild. $75 later all that S.O.B. did was strip the paint off the bowls and sync covers and put in the new parts (that I supplied). They still dumped gas and now the bike needed more work. I found a buddy who knew his way around them and he'd tell me what to do and I'd do it. Once I had been into one of them I realized it's a piece of cake, I was just afraid to dive in because it was foreign to me. What's even better is these things only have 2 carbs to mess with, the KZ has 4 :p.
 

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lets see... muzzy sytem, k&ns, dynojet stage 3= ran like crap
jardine sytem, stage 1 jetting and uni air filters= runs superb
 

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Discussion Starter #13
Nick D said:
Are you looking for pipes because you want to go back stock, or just to see if it fixes it?

Yeah, the main reason is i just want to see if it'll fix the issue. I'll let the techron cleaner run through it's course to see if it'll solve the issue.
 

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it won't completly solve the problem. It won't get all the little crud from the jets trust me I've tried many times because I'm to lazy to take them off and clean them.
 

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When you change your full exhaust system, it is always recommended you re-jet the bike. Occasionally, you have to do this with slip-on pipes as well. You'll know within the first ride. Look for the telltale signs: Stalling, sputtering, lost horsepower.
 
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