Polaris RXL Information and Troubleshooting

Someday this might be well organized. For now it is a random assortment of tips n trick, and info that I have come across. Most of this applies to the Indy 500 EFI as well.

Polaris RXL cylinders are different than the carbed Indy 650. The intake ports and transfer ports are considerably larger on the RXL to allow for the EFI.

Get a new battery every year. The EFI on the RXLs demands a full 12 volts. Anything less and it will start causing problems, leaving you chasing ghosts. Start with a fresh battery and verify that it is at least 12 volts.

Get two of them. You will do a lot less head scratching if you can check parts by substitution. RXLs don’t bring that much money, I got one of mine for $300 and one for $500, plus a junk one for $150.

The expensive Select Monitor is dead. You can buy an interface cable that hooks up to the EFI computer and the USB on your laptop for $15-20. There is a program out on the net for free that will interface with the computer. Info 1, Info 2, Download.

The PROLIFIC version  of the interface did not work for me, I have a version with the FTDI chip on the way. Make sure that it is a FTDI chip and has TTL level signaling. Digikey has them for about $20 for a self contained smart cable.

If you have a fuel problem, go to the auto parts store and get a cheap universal ‘Noid’ Light. It tells you if the injectors are firing. If  they aren’t, check the wiring to the stator, and especially the trigger coil. If that is in order, chances are that you have a bad dropping resistor. Those are a little silver box down by the battery with a plug on it. They drop the voltage on the injectors from 12v to 5v. I have replaced several of these.

Pro-X pistons are cheap. Pro-X is well known in moto-cross, but they only make one snowmobile piston. Lucky us, it is for the Indy 650 and 650 RXLs. I used a set in my last rebuild and was very impressed with the quality. I liked that I got them 3/$99 too.

Why does it take two pulls to start my RXL? You can pull it the first time with the force of Thor, and it won’t start. The second pull it will start up on the first or second compression stroke.

The deal is that the first pull sets up the EFI timing with the rest of the engine. Once it has that and the sensor inputs it will fire right up. The exception to this is if you just shut it down and the computer still has the info, but doesn’t take long to time out. I don’t even pull mine hard on the first tug any more. It is a waste of effort.

Fuel Filters– You can use a G4777 Fuel Filter on the RXLs. For a Fram version expect to pay 10-15 dollars.

Battery– I have been running a 12n9-4b-1 battery in my RXLs instead of the standard YB9A-A. The 12N9 is a common motorcycle and ATV battery, and therefore cheaper and easier to find. The amp hour and cold cranking amps are the same, the 12N9 is in a 1/2″ shorter case.

By going to the cheaper and more common battery there are more choices.  I am running sealed maintenance free 12N9 AGM batteries that sell for less than $40 shipped.

Belts– I have had mediocre success with aftermarket belts, so I am a stock belt guy. The RXL takes a Polaris 3211042 belt, and there is a close tolerance version at 3211045.

Fuel pressure regulator– I had a bad fuel pressure regulator in one of my RXLs. It wasn’t holding pressure in the fuel rail, and caused a hit and miss bog depending on if the pump was cycling right then or not. When I tested it with a gauge it would go to pressure and drop right away. A good regulator will hold pressure in the rail.

The fuel pressure regulators from Polaris are no longer available, but you can get an aftermarket universal fuel pressure regulator from E-Bay or the local speed shop. This one is adjustable and has a gauge for $26 shipped.

The universal flange will not fit the fuel rail, but once you remove the rail and old regulator, the hole for it could easily be tapped and fitted with a hose barb fitting to adapt the universal regulator.

The advantages to the aftermarket regulator are the gauge and the adjustable fuel pressure. You can run the engine a little richer or leaner by adjusting the pressure on the regulator, and see right where it is on the gauge.

The RXLs should run about 37 pounds at the rail, and be able to hold the pressure. Test that with a T fitting, a fuel pressure gauge, and an extra length of line on the belt side of the fuel rail. A straight pump test should show close to 70# and be able to hold pressure for a minute plus.