Tuning the exhaust - Sportbike Forum: Sportbike Motorcycle Forums
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post #1 of 18 (permalink) Old 04-18-2006, 05:17 PM Thread Starter
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Tuning the exhaust

I just received my Yoshimura TRS street slip on, and I check the Yoshimura website if the bike needs any adjustment or tune up, since it'll be exhaling differently now. They suggested, "it is important to at least adjust the pilot mixture screws and shim the needles 0.5-1.0mm..." for slip-ons. Now how exactly would I know it's tuned to meet the requirements of the exhaust, how would I measure the calibration ? I am trying not to get the bike to run too rich or too lean, in fact, I like the current state of lean flow. Thanks.
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post #2 of 18 (permalink) Old 04-20-2006, 07:52 AM
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That's why you pay seasoned carb tuners like me to work on your bike.

ANYBODY can install a jet kit etc... Very few can actually tune one optimally. You have to have a certain level of knowledge for how each fuel circuit flows into the next one & at what rpms throttle positions it occurs. Most of it comes from experience & even with a dyno to give you accurate A/F ratios it is still a time consuming & sometimes complicated process to do it correctly.
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post #3 of 18 (permalink) Old 04-20-2006, 08:23 AM
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Short hijack, sorry Z.

So if I get a Micron slip-on for my bike (I know there not great, but its the best one of the 4 made for my bike that I can afford) I need to get the fuel/air mix adjusted again?

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post #4 of 18 (permalink) Old 04-20-2006, 08:53 AM
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Every bike regardless of whether it is carb'd or Fi & even with a stock exhaust needs the fueling altered to be optimal. Changing the exhaust only makes it that much worse & in more need of being corrected in almost all cases.
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post #5 of 18 (permalink) Old 04-20-2006, 09:17 AM
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Thanks for the info.

Sepias

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post #6 of 18 (permalink) Old 04-20-2006, 10:42 AM Thread Starter
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Quote:
Originally posted by Lord Duckhunter
That's why you pay seasoned carb tuners like me to work on your bike.

ANYBODY can install a jet kit etc... Very few can actually tune one optimally. You have to have a certain level of knowledge for how each fuel circuit flows into the next one & at what rpms throttle positions it occurs. Most of it comes from experience & even with a dyno to give you accurate A/F ratios it is still a time consuming & sometimes complicated process to do it correctly.
HAHA, sure, can you make a trip down south?

I am not interested in putting jet kit, it is a slip on - one of the reasons I didn't want to get full exhaust is to avoid jet kits. I just need adjust the carb mixture screws enough to match the new exhaust. Job isn't difficult, but just getting it right and to measure the difference. Would I need carbs synchronizer for it, or is there educated guesswork to figure it out?
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post #7 of 18 (permalink) Old 04-20-2006, 11:04 AM
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Just doing the mixture screws themselves is pretty easy. First thing is to make sure you have the proper tool to do them. Many Keihin carbs have a special D-shaped tool that fits the screw head. First you turn them all the way in & count the exact turns on each screw until they are fully (BUT LIGHTLY) seated. might be 1 full turn or 2.5 turns etc...

Depending onwhere they were to start with you'll probably end up turning them back out at least one full turn past that point. When done properly you will probablyhave to reset the idle a little bit to get the rpms back down to the proper idle speed when you are done. The good news is you'd be pretty hard pressed to screw anything up just messing with the idle screws as they could always be reset back to stock & you can start over if you have too
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post #8 of 18 (permalink) Old 04-20-2006, 09:28 PM Thread Starter
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Right, thanks, I understand. What's still lingering is would turning the screws make any difference? How do I know that I'm getting the results I need? Or could I just leave them as they are? As you said they may raise the idle a bit, but same could be done with the stock exhausts on. Thanks again.
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post #9 of 18 (permalink) Old 04-21-2006, 05:26 AM
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It's kind of a tricky thing, cause you have to listen to & feel the motor to get it right. You are basically looking for a good healthy lope to the motor without it being a fast idle kind of thing...

There is a pretty wide range of adjustment on the screws that will work for you even if not optimal, but if you go to far one way or the other then you will start to notice problems like hesitation at very small throttle openings, or a miss when you blip the throttle or even a strange dip in power when you upshift through the gears just as you crack the throttle back open etc... If anything weird starts to happen at very small throttle positions then you've probably gone too far on the adjustments

Oh & also stay away from K&N air filters on that bike!
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post #10 of 18 (permalink) Old 04-21-2006, 08:06 AM
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Whats wrong with K&N filters? I dont have them in my bike, but everyone seems to hate them and I'm curious as to why.

Sepias

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