problem with pipe or jetting issue?

1333 Views 11 Replies 5 Participants Last post by Big Air, Sep 23, 2002

TonyR

Discussion Starter · Jul 15, 2002

A buddy of mine just bought a white Z and purchased the full Yoshimura exhaust for around $500. When installed and jetted to the recommended size, it ran great for the first radar run then couldn't run as good again and started to (what seemed to be) misfire. Could this be a jetting issue or a problem with the pipe? We are in Michigan.

Thanks.

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Fullthrottle

· #2 · Sep 14, 2002

Tony,
What did you do to correct the problem? I just got my full Yoshi system installed and it ran flawlessly for the first 5min, now it stumbles at 1/8 throttle and back fires.

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WP

· #3 · Sep 15, 2002

I don't know what elevation you guys are at, but at Trinity they found the Yosh jetting to be too lean. If you remove the airbox lid, screen, snorkle, move the needle spacer to the bottom, then install a 165 main, you should be stylin. It probably ran good the first run because it was cold and running lean didn't take as muck of an affect.

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Fullthrottle

· #4 · Sep 15, 2002

Well the reason it was stumbling is because it was running out of gas

:
Once that was fixed I took her down the road then pulled the plug. It was white, so I agree, thew 150 is to lean. I didn't have a 165, so I used a 162.5. It still appears to be to lean. The next size larger I have is a 175. It's in, but now it's pouring down rain. Soon as it stops, I'm going for another run. I hate to mess with the needle because it's running so well. No stumbles, or hesitation anywhere. I'm running the K&N with 8-1" holes drilled in the lid and the snorkle on. I never would have imagined I'd run lean with this set-up. The Yoshi made a big difference on the bottom and rev's a lot better on top. I'm pleased...

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WP

· #5 · Sep 15, 2002

175 is too rich and will hamper your bottom end. With the lid still on the 162.5 should be ok. Put a little more than 1 run on it to see how it does. Do the needle anyways, it will help.

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Fullthrottle

· #6 · Sep 15, 2002

Your right, 175 is too rich. Hard stumble at 3/4 - full throttle. I'll order the 165 tomorrow. Thanks for the info.

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Fullthrottle

· #7 · Sep 19, 2002

Well I got the 165. It stumbled at 3/4 throttle too, so I removed the airbox lid and WOW, ran like a scalded dog! The damn plug still looks white to me Though. I guess I'll leave the airbox lid off, but I don't want to run it too lean. Should I order a 167.5 and 170 to test? Whats the largest jet you guys with full aftermarket exhaust systems and K&N's without the airbox lid run?

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kpracing12

· #8 · Sep 20, 2002

Yoshi Pipe

Does the Yoshi pipe have a larger diameter header than stock? Pete

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Fullthrottle

· #9 · Sep 20, 2002

Yes, the stock header is 1.5" and the Yoshi is around an 1/8" larger in diameter.

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Big Air

· #10 · Sep 20, 2002

QUOTE

Well I got the 165. It stumbled at 3/4 throttle too, so I removed the airbox lid and WOW, ran like a scalded dog! The damn plug still looks white to me Though. I guess I'll leave the airbox lid off, but I don't want to run it too lean. Should I order a 167.5 and 170 to test? Whats the largest jet you guys with full aftermarket exhaust systems and K&N's without the airbox lid run?[/b]

i am running a 152.5 with the fuel mixture turned out 3 and 3/4 truns and a 25 pilot jet k & N filter no snorkel or lid and ride at the dunes most of the time and i am just about chocolate brown. i may go to a 155 and i have a yosh comp system.

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Fullthrottle

· #11 · Sep 20, 2002

At this point I'd dance a jig to see chocolate brown. I ordered a 167.5 and 170 main, also a 25 pilot. They should be here Wed. I'm ready to stop wrenching and start riding! Did your Yoshi wake your Z up as much as mine? Pulls harder on the bottom and revs longer on top here. I'm pleased with it..

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Big Air

· #12 · Sep 23, 2002

my yoshi did wake up the machine alot. and this weekend my chocolate brown went to white, have no idea why. so i went to a 155 main with the 25 pilot, needle is on the 3rd groove and the fuel mixture is 3.5 turns out from seated. it is super close to chocolate brown again, and it pulls way harder now all the way through. i think i got it pegged now but i will let you know if the tan color leaves again. it shouldn't though the bike really runs great now.

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