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Discussion Starter #1 (Edited)
Just read an add for a jet kit that says "Once you install or modify an exhaust or intake, you have put your bike into a leaner condition that will eventually destroy your engine due to heat from running lean. If you notice any popping, you are extremely lean."

Since I installed my aftermarket exhaust, I have been getting a lot of popping.The manufacturer of my aftermarket exhaust claims jetting is not necessary. However, does the popping really mean my engine could suffer damage? Do I NEED a jet kit?
 

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Have a look at your spark plugs. The color of the ceramic tip will tel you a lot about how rich/lean the engine's running.

Popping in the exhaust is caused by unburnt fuel igniting when it hits the hot header pipes, so if anything that would suggest a rich mixture.

If you read the threads on here regarding re-jetting etc (especialy the sticky by Bolserst) you'll find that most ZR-7's tend to run rich, especially at the bottom end of the rev range.

I have a 'Fuel' end can fitted, which the makers claimed needed no changes to the jetting and my spark plugs confirm that.

If you had bought a full-on race exhaust, that would probably upset the back pressures to a greater extent, then yes, a jet kit would help fueling and boost power even more.

Jet kit manufacturers have to say that you NEED their products, as the comparative complicaions ($ £ $ £ $) of installing new jets (as compared to fitting an end can) will put most owners off.
 

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Discussion Starter #3 (Edited)
Extremely helpful. Thank you for the insights.

By the way, does anyone know if motospecialties still offers a jet kit for the ZR? I couldn't find it on the website.
 

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Johnny Blue Lightnin'
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The motospecialties kit is no longer available.

I think the ZR is lean on the bottom and rich on top. Your ZR popped on decel with the stock exhaust but you couldn't really hear it. You can make it pop just a bit less by plugging the AIS hose. (Commonly referred to incorrectly as the EGR on the ZR) Do a search on how to plug it or remove it. Jetting really is not necessary with just an aftermarket muffler.
 

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As far as I'm aware the only jet kit available is the Dynojet and maybe the Ivan's.
It's not unheard of for a second-hand jet kit to be made available by forum members, especially if they trade their ZR7 in at a dealers. (That's how I aquired mine! :))
Try this thread for more information :- http://www.riderforums.com/showthread.php?t=38791
 

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Discussion Starter #6

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FactoryPro do a great drop in kit with no slide drilling required.

HERE
 

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Much advertising, specially the ones for medical conditions and their remedies, are designed to scare people so they would rush and buy their products. The ad you saw about the carb kit follows the same pattern.
 

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Discussion Starter #9
Was hoping it was nothing more than standard fear tactics employed by advertising/marketing folks, but I figured I would be wise to ask folks who have the necessary mechanical knowledge to know for certain. I appreciate your mechanical insights.
 

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If you were a little lean, you could always turn your mix screws out a bit. and/or put a shim under the needle. You don't need to remove carbs for any of this.
Hey i was wondering where these mix screws are. Are they the same ones you use to sync the carbs. would i want to turn the screws clockwise or counterclock wise. Where could i find this needle shim, and could i rig something up with a washer instead?
 

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