Jetting confusion

norwegian

norwegian

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Hi
I saw in the tech pages that you could "drop 1/2 of a main jet size". I don't understand that. Wouldn't one main jet size be the difference between say a 143,8 and a 141,3? There is not a jet between that in the jetting chart. What am I missing?
 
Norwegian,

I'm new to sledding, but have a lot of experience with motorcycles. On bikes, jetting sizes were 140, 145, 150, etc. in increments of 5. I'm guessing a 143.8 is a half size.
 
That's just the point, there is nothing between 143,8 and 141,3, there is no 141,1.
 
Are you saying that the difference between 142,5 and 140 is ONE jet size?
 
Hi, can someone clarify this once and for all?
Another thing, when the jetting on the venture 500 says "down to -7C". Does that mean I can still ride the sleds colder than that, the main jets aren't used at low rpms?
 
I never saw this thread before but understand your confusion. I've never heard of dropping 1/2 a jet size either. But then again...... why ??? When in doubt, error on the big side for a safety margin.

And on your 500, there's quite a bit of safety margin in factory jetting. If it says a jet is good down to -7, I'd think it'd be be good to -15/-20 for normal trail riding, but then I'd stay away from a 5 mile stretch's at WOT lol.
 
This is a great question! Not trying to hijack but, "what" increase of fuel flow would there be between say 140 and 141.3? Would it even be significant? Is this what they mean by 1/2 a jet size between 140 - (141.3) - 142.5?
 
Northern srx, that's also what I am wondering about. Don't worry about the "hijacking"
 
You might be able to accomplish what your looking for with the plastic shims/washers on the jet needle.The needle usually has one on top and one on the bottom of the e clip,by putting both on the top you drop the needle into the main jet by the thickness of the shim and you lean out the jetting however minuscule the amount may be.It would be equal to about half a setting this way versus moving the e clip one notch up with a shim on top and bottom,that would be one complete setting change.
 
Normal jet sizes would be 140, 142.5, 145, 147.5, 150. The half sizes in between would've be like 143.8, 146.3, 148.8. I am not even sure how many in between sizes are available. I always thought it was a special order Yamaha thing.

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