Polaris Indy 500 Oil injection HELP!

[snowman72]

I am looking for some advice on the best route to modify the oil injection set up on a 97 Polaris Indy 500 with a newer style 500 motor.


I bought a '97 Indy 500 for my son at the end of last season, (got a great end of season deal) the previous owner replaced the original (blown) motor with a low mileage one from a newer INDY 500. The '97 had oil injection with banjo fittings bolted to the cylinder block, delivering oil right at the cylinder intakes. The newer 500 motor was one from a (2001 or 2002 if I remember correct) which was set up to run with rack style carbs that had oil fittings in the carbs. So what the previous owner rigged was a brass fitting mounted in the bottom of the rubber carb boot. It does work, and we put a couple hundred miles on it with no problems, but I don't like the idea of having a fitting in the carb boot, even though it is sealed up.

I have two options:

1. Pull the cylinders and find/have a machine shop drill and tap holes for the banjo fittings to mount into the bottom of the cylinder like on the original '97 motor.

2. Mount new oil injection fittings/check valves into the sides of the 38mm round slide carbs. There is already a brass nipple on the engine side of the carb that is closed off with a rubber boot, I can drill it out for the new fittings. This would put oil back to the motor like the way the newer style one is.


My nephew has a Polaris 550 SuperSport that has oil injection at the round slide carbs, so I know Polaris used this on many of the mid 2000's sleds and it works.

It seems like the carb route is an easier and less expensive way. Anyone with oil injection experience that can pass along some technical advice would be appreciated. Oil injection systems seem fairly simple, I just don't want to burn up an engine!

Here is the current oil injection set up from previous owner (I added the hose clamps as a temporary security so that the fittings could not fall out). See the rubber nipple next to the vent line and gas line, that is where I could mount the new injection fitting.


These are the carbs that the motor originally ran


Thanks in advance!

Todd

 

[mjkaliszak]

I had to read this several times... my mind is not what it used to be. I would agree that the CARB option is the simplest but not sure about drilling that area out ?
What is wrong with the " rack " or Mikuni TM style carbs in the pic that you aren't running them ? I assume you only have the " round " slide set up .
You could always add some oil to the fuel, every fill up ( pre-mix ) just to play it safe also.

 

[snowman72]

Thought about converting to the TM flat slide carbs, but I would need to buy those and possibly new throttle cables and air box. I also thought about the premix option, but that's always a hassle, especially when the whole family pulls up to the pumps and trying to fill everyone up and get them out of the way for the next group.

Thanks for the input!

 

[xcr440]

If that little fix worked last year, is there any reason it wouldn't this year? Those carb boots are pretty tough, until they get old. I'd run it like it is, and check them periodically.

 

[snowman72]

Good point, just seems a little to jerrry-rigged. Just peace of mind to have it more securely fastened.

 

[mjkaliszak]

Thought about converting to the TM flat slide carbs, but I would need to buy those and possibly new throttle cables and air box. I also thought about the premix option, but that's always a hassle, especially when the whole family pulls up to the pumps and trying to fill everyone up and get them out of the way for the next group.

Thanks for the input!

I have a extra air box off of a 2008 RR ( 600 ) . It could be yours for the price of shipping ( free in other words ) if you go that route. How about picking up a set of the Boyssen ( I forget their product name ) but they have a small rubber boot area and a solid flange that could be trilled & tapped with a #10 pipe plug tap ??? Just a thought or maybe a set of aluminum spacers that could also be drilled and tapped thru the side ??? You could do that yourself with a hand drill and a little skill.
I have a service manual, PDF (of the 600 RR ) that I could e-mail you if you wanted to convert. Not sure what help that would be other than a component list & some ideas ???
My 6hundro air box has a rub spot in the bottom from the jackshaft, it could be sealed easily. In our RR there is little room and a lot of vibration, the wear spot bothered me.... that is the only reason I changed it out.
The carbs may be able to be had from a used part place like ( BK boats or online HCS part section ???? ) just some ideas.
If you need any help or suggestions for a conversion , I would be glad to send you any parts I have extra ( air box ) old boots ect.... for free.
Just a priliminary warning ( the POO boots are notorious for going bad )... There is a place in IOWA called JS Powersports that also has a big POO racer following & POO tech tip page on their website. May be another source of help.
The 1 tech's name is Nate ??? he is always on HCS in the racer forum, good guy and they may have extra parts laying all over for that carb convcersion....

Done ramblimg now !