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Ok, I just installed a factory pro jet kit in my Suz RF900. The factory pro kit recommended 110 main jet, 3rd notch on needle, and pilot srews 2.5 tursn out, for my bike with the mods it has (d&d slip on, K&N filter, ignition advancer) .

Stock size main jet for my RF is 112.5. So why would the factory pro kit recommend something smaller?

Also, I just looked on dynojet's website and they recommend in their kit a 118 main jet for my bike with it's set up.

My bike is running nice so far with factory kit but I was just wondering if anyone knew why there was a difference with the factory pro and the dyno jet kit, different R&D results by the two?
Why would factory pro reccommend something smaller than what is currently the stock size?
 

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Different numbers

Don't worry about it. My understanding is that everybody uses their own numbering system.

Dyno the bike with the air/fuel ratio test. This is the important indicator of where your bike is running. If you can't do that, check the color of the spark plugs.

I hope this helps.:D
 

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I think Factory is the one that uses the standard sizing, and DynoJet uses their own.

I have a DynoJet and had no problems with it.

The only difference that I have heard the between Dyno and Factory is that Dyno will get you different sized jets if you need them (supposedly faster) and the aboved mentioned sizing difference if you decide to take it to someone else to finish your work.
 

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Dynojet and Mikuni jet numbers DO NOT match. Secondly...the jet kit may very well call for a smaller main. Needle taper plays a major role as well. The dynojet needles may be very tapered and require the use of a smaller main.
 

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Scot said:
Dynojet and Mikuni jet numbers DO NOT match. Secondly...the jet kit may very well call for a smaller main. Needle taper plays a major role as well. The dynojet needles may be very tapered and require the use of a smaller main.
My thoughts exactly. Alot of times you'll find after market needles are to aggressive for street riding. If your bike is running fine, I wouldn't worry to much.
 
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