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Discussion Starter #1 (Edited)
Good Morning Gang,

I just purchased a '07 660 Rhino with a long list of mods, and I'm pretty certain the previous owner didn't jet it correctly. Here's a list of the mods that will impact jetting --

Trinity 686 11:1 kit
Tinity ported head with big valves
Hot Cams Stage 1 camshaft
41mm FCR carb
K&N hi-flow air intake kit
Gibson exhaust (single muffler)

Oh, and did I mention it has a Innovate air/fuel gauge?

Here's why I believe the jetting is off... it starts and idles fine and the a/f guage is showing around 10.5 a/f ratio at idle after the O2 warms up. Off idle (while on the needle) it spits and sputters and the a/f ratio is still at around 10.2-10.8. I've only been able to run full throttle for short spurts (only driven it down my street and back...first outing is this Sunday), but it seems to pull very hard and runs strong and smooth. The a/f ratio at full throttle is around 12.0-12.5.

I think the main is right, or at least very close to right. I'm not certain where he has the needle at, but my guess is its too high and I think he has too large of a pilot jet (52 by the documentation provided). Main jet is a 160. I live at about 250 feet elevation.

I'd like to know what you guys running similiar engine mods are running for jetting and needle position. Shouldn't I be looking for a consistant a/f ratio around 12.5 or even 13.0?

Thoughts? Suggestions? Comments?
 

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you are way too rich...

Start with the largest pilot jet that will give you 12.5:1 with the idle screw at least one full turn out from fully seated...

Put the needle in a neutral position...

select the main jet that gives you 13.5:1 at wot under max acceleration after a/f gauge settles once you floor it from a stop...

From there experiment with smaller pilot jets in order of next available size...

Reset idle a/f to 12.5:1 with screw each time...

Each time you replace pilot jet and reset idle a/f test wot and reset main again if needed to 13.5:1...

Continue this way until you find the fastest pilot/main combo in 0-300'

From there you can experiment w/ idle a/f setting and needle position...

Never make two changes at once trying to guess ahead it will hurt you in the long run even if you guess right you won't know it's right...

pm me your email if you need more on this subject...
 

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Discussion Starter #4
This is great info!! Any guess on where to start with the pilot jet? I think the main is pretty close, I could probably drop down to a 155 and be almost dialed.
 

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Discussion Starter #6
I'm sorry, didn't mean to imply that I hadn't read what you wrote or didn't understand. I was just asking for a little guidance on a pilot jet size to start the tuning from since the 52 is obviously too large. :)
 
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