JA World Formula jetting for Lincoln

Chris Dorsey · Joined: 01 Dec 2010 Posts: 14

My daughter will be joining me in Lincoln this week for the Pro and I need to know where to start. Any suggestions for JA World Formula jetting? Thanks!

Joe Ricard · Posted: Tue May 22, 2012 5:19 am Post subject:

my air density gauge is averaging about 93 during the day. 85 degrees and 75% humidity. we run a 100 jet down here on the gulf coast @ zero elevation.

But I promise your mileage will vary.
_________________
Arrow AX-8/ Rotax Sr.

Alan Sheidler · Joined: 09 Aug 2001 Posts: 471

Unless you are running at an extreme end of the jetting range, it really just will not matter for the WF. That motor is not at all sensitive to jetting like a 2-cycle or shifter kart is.

If you are within a couple of jet sizes from what is delivered from Briggs, you should be good. We have run our WF in venues from coastal to high plains, and everywhere in between except mountain elevations. Just ran 100 or so laps at PittRace last month, and I think the elevation there is about 1200. The engine has run GREAT everywhere, as long as the pilot jet was clear the the plug was good.

Have your JA concentrate on driving, and don't stress out over the last 1/10 HP you might get from having the perfect jet in the carb.

Chris Dorsey · Joined: 01 Dec 2010 Posts: 14

Thanks Alan. We've been running at 6,000' so I'm sure we are pretty far off with our 90 main. Just looking for a starting point. Probably put a 96 in and see how it runs. Thanks again!

Joe Ricard · Posted: Wed May 23, 2012 4:51 am Post subject:

WF also seem to not be like each other.

93 in Blythville last year and we were on the ragged edge of burning it up. 1500 EGT and 475 head. We changed it up and all was better.

Alan is right they are durable little buggers.
_________________
Arrow AX-8/ Rotax Sr.

Chris Dorsey · Joined: 01 Dec 2010 Posts: 14

For future reference, the 96 main ran really well in Lincoln. Replacing the WF air filter with a Swiss Chessed Gatorade bottle really seems to help as well :-/

Joe Ricard · Posted: Mon May 28, 2012 5:22 am Post subject:

Cool, did you lose the Green air filter?

Watched the Juniors and KM Pilots on Ustream. Nice job to all drivers, now go get FTD for the event.
_________________
Arrow AX-8/ Rotax Sr.

Chris Dorsey · Joined: 01 Dec 2010 Posts: 14

We ran our Green filter but one of the JB karts thought it was optional.
The Junior group at the Pro was great. They had a great time and competition was pretty good.

Joe Ricard · Posted: Mon May 28, 2012 8:29 am Post subject:

Does anyone have an Air Density measurement to go along with the 96 main jet?
I know it was hot as Hadies, but what about humidity?
_________________
Arrow AX-8/ Rotax Sr.

Steve Ekstrand · Joined: 15 Dec 2008 Posts: 6

It was my understanding that in WKA and IKF sprints with the WF classes you have to run the Green filter. You can't even change brands to a similar filter like K&N. I would assume that would apply to us as we derive our configurations from that foreign world I know so little about.