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Discussion Starter #1
Has anyone experienced a problem where the engine tends to stumble / bogg a bit when you are normally starting from a standstill? This is from 1,100 - 2,500k~ . I am not sure if this is because I have installed a yoshimura bolt-on pipe. Would this change in exhaust be the cause of this studdering / hesitation problem?
 

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It may be due to the new exhaust output but it's just a bolt on so doubt it. How many miles are on your o4'? And anything under 2000 rpm's for a Gixxer is starving the BEAST!
 

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Mine does the same thing, started when I installed a yosh trs. I've heard of others doing the same thing. Let me guess, when you start it cold and it's warming up, it goes into a really lopey idle too? I've gotten used to it, but you could probably improve it with a pc.
 

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It has about 8,900 miles. I have changed the oil regularly, but have never changed the air filter. Ive put a lot of miles on it since last summer.
 

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Discussion Starter #5
YES, exactly... when its cold it feels like its more likely to studder, then i press the gas more and then it takes off normally.
 

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All engines need more fuel to run when they're cold, so they in turn run lean. If it goes away when it's warmed up, then it's normal. No biggie.
 

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What's your idle set at
After the yosh TRS it dropped to 900 or so
I had that problem until I adjusted the idle up to 1300 when warm
Helped allot
 

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Discussion Starter #8
My idle is at about 1,350 more or less. The hesitation still continues even after the engine is at operating temperature.
 

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Discussion Starter #9
Guess I will be installing a PCIII usb in the near future, any of you guys got one?
 

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Mine does the same. It has no power off the line, then likes to expload at around 3000 or so ever since my TRS. A friend told me it is running lean now, and that someone with a Yoshi box could "give it a +5 in the mid and the low" and it would be running like a champion again. I haven't done anything to fix it yet...
 

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No problem with my 750. I did install a PC3USB though along with a Two brothers pipe & map. It will lope a little cold, But goes away completly as soon as it warms up.
 

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Mine is the same way, at start up its a bit lopey then calms down as the temp raises. I notice a stumble too with my yosh trs bolt on. Mine has a tendency to sound like it is going to stall if I let the clutch out in 1st completely but not give it an throttle, almost just coasting??? I know my friends 04 R1 cruises fine with no throttle in first at about 7 or 8 mph. Any ideas???
 

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Like many on here have said you have to raise the idle up, I raised mine to 1400 based off of others suggestions and it works great. The reason that the bike runs rough when cold is because it hasnt had time to set it's self in closed loop meaning the oxygen sensors havent heated up enough to be used so the computer puts itself in open loop. Basically open loop is set parameters in the computer to comand the fuel and ignition timing. Once the O2 sensors have heated up enough to become active it will go into closed loop where it will run based off of real numbers from the exhaust and that allows the computer to adjust and run smoother.

It is nothing new or anything to worry about, open loop will always run rougher than closed loop. Since the muffler is allowing more airflow this will cause the engine to stumble a bit at lower RPMs, just raising the RPMs will make it idle smooth. Refer to your owners manual for idle adjustments, it's very simple and will take you about 5 minuets if you have never done it before.

Good luck!
 

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Just to let everyone know and to finish up this post because it was helpful. I had the same problem. I have a yosh trc slip on and i kept getting a stumble. I pulled the plugs and could tell it was running a bit rich. (the plug ends seem to be black. Also, it smelled like alot of gas whne idling) Anyways, i pulled the plugs and put new iridium plugs in and this cleared the problem completely. Hope this helps!
 

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These engines have no torque at lower RPMs. Of course they're going to stuble down low. Stop taking off like a grandma and keep the RPMs above 2500-3000.
 

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Like many on here have said you have to raise the idle up, I raised mine to 1400 based off of others suggestions and it works great. The reason that the bike runs rough when cold is because it hasnt had time to set it's self in closed loop meaning the oxygen sensors havent heated up enough to be used so the computer puts itself in open loop. Basically open loop is set parameters in the computer to comand the fuel and ignition timing. Once the O2 sensors have heated up enough to become active it will go into closed loop where it will run based off of real numbers from the exhaust and that allows the computer to adjust and run smoother.

It is nothing new or anything to worry about, open loop will always run rougher than closed loop. Since the muffler is allowing more airflow this will cause the engine to stumble a bit at lower RPMs, just raising the RPMs will make it idle smooth. Refer to your owners manual for idle adjustments, it's very simple and will take you about 5 minuets if you have never done it before.

Good luck!


These bikes (from the factory) don't have oxygen sensors.
 
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