AAEN pipe jetting on Indy 500

[fabiodriven]

SO I've got a set of AAEN pipes I'm putting on my 89 Indy 500. My question is whether or not I will have to do any jetting to accommodate these new pipes. I'm assuming I will, but I'm not sure. If it's any help, last year when I was riding near full speed the sled would actually pull a little better with the throttle not quite wide open. In other words, it runs better with the throttle at 85-90% than it did wide open. I will be taking the motor apart to do crank seals and rings/hone if needed. Thanks.

[lndy650]

ive done quite a bit with the 500's. they are touchy bastards and hard to get tuned in but once they are they run good... if you get new crank seals check the main bearings while you have it apart.
first try 2 sizes up on your main jets turn your air screws in all the way then 1-1/2 turns out. i think the 500 had 280's stock so try 300's.
do a wot run and check your plugs. once you get the main jet tuned in you can start changing pilots/raise the needle a notch if it needs it. usually just the main needs to be changed.
the 500's made about 72hp stock and the Aaen twins didnt raise it much but they do change the powerband from around 7800 to about 8100. if you gut your airbox youll be making around 76-78hp. the decker twin pipes were the best but they are hard to find.
if you want to go all out with this thing let me know i have dynos of some modified 500's and some tricks...

[fabiodriven]

Thanks for the response INDY.

So how do I "gut" the airbox?

What do you think the cause was of it running better at 90% throttle? Lean or rich? My guess would be lean, possibly from the crank seals. Does that make any sense?

[lndy650]

it defenitly could have been a lean mixture or maybe your clutching is off and you were over revving? easiest way to tell wide open fuel mixture is a plug check.
to gut the airbox you have to take out the shelf so its open inside.
i remember now Aaen dosent recommend thier twins on a stock engine but a ported engine they respond well. they wont hurt anything its just that the indy500 stock was extremely de-tuned

[lndy650]

looking up some old dynos..
stock 89 indy500 with 270 mains 71.9@7800rpms
same as above with gutted airbox 73.3@7800rpms
gutted box and decker twins 77.4@8250
gutted box and aaen twins 69@8200 ouch!(this is where the stock engine dosent mix well with aaens twin pipes)
--------------------------------------------------------------------------------
now with 39.5mm bored carbs, trail porting(raised ex port modified transfers and .010 off the head), timing advanced to 32 degrees BTDC and gutted airbox
stock pipe 280 main 81.7hp@7800rpms
Aaen twins 290 main 78.5@9000rpms
Decker twins 290 main 88.6@8250rpms
PSI twins 80.9@7750rpms

i forgot how bad the Aaens were o the 500 i think your better off with the stock pipe lol

[lndy650]

Heres a good laugh at DG i found.
stock xlt 600 95hp @7800(remember single pipe turd!)
triple DG pipes 95.5 @8000! wow DG should have quit then!
Deckers 108.6 @8750...

[fabiodriven]

Who does porting on these and how much does it cost?

It's been years since I had a snowmobile motor apart. The last one I did was a 1970 Ski Doo Nordic 399. Should I use OEM head and base gaskets? Are there aftermarket gaskets readily available that aren't junk?

I wasn't planning on splitting the crank, so obviously I won't be doing anything with the inner bearings. Would I be better off replacing the outer crank bearings or just leaving them since I'm not doing the inners anyways?

[lndy650]

i did my own porting but Aaen would port it for thier pipes. im not positive on the price but between 3-500 i would think. its pretty expensive. Olaf Aaen is in the snowmobile hall of fame and built some awesome pipes so im sure with thier porting your pipes would work good
http://www.aaenperformance.com/Snow_Home.asp

[fabiodriven]

Heres a good laugh at DG i found.
stock xlt 600 95hp @7800(remember single pipe turd!)
triple DG pipes 95.5 @8000! wow DG should have quit then!
Deckers 108.6 @8750...

Yikes... I really am not crazy about DG, although thier pipes for the Yamaha RD's are pretty good.

[fabiodriven]

Yeah, it's about $500. That's a bit pricey. I wonder if there's anyone else who does it any cheaper?

[lndy650]

you could try other companys but most are about the same price. some might do it cheaper because its an older engine. SLP should defenitly have old specs on the 500. if your not looking to spend much stock porting with the cylinders raised .040 and the head cut .060 and 5/8" cut off the stock pipe will give you around 85hp. but make sure to run good 93 octane fuel.
cut the stock pipe in the straight section between the spring tabs and the first weld on the center section.

[fabiodriven]

Ahh skrew it. I think I'm just gonna do my little overhaul, jet it, and slap the pipes on there. If I start getting all crazy the thing won't be done until spring and I'll be spending $1000 on a $500 machine!

Thanks so much for all the advice Indy.

[lndy650]

ya its better to just ride it and the pipes will sound great

i went through a indy 500 phase years ago...the one i got now is around 90hp and a blast to ride