I've been challenged by my son to make his 1995 Indy Starlite 250 perform better. For the many who have not seen one of these sleds, they are the same chassis as Indy Lite 340 but with a 250cc fuji single lunger.

My son is only 10-ten years old (going on 16) so mounting an 800 under the hood is out of the question (for know). I figure a pipe, jet and clutch work will do nicely since it only weights 370 lbs. Plus, just dropping in a 340 fan engine is not enough of a challenge in my eyes. Making a 250 run like a 340...now there is a challenge!

I would like any technical input I can get before diving in.

Recommended pipe dimensions, possible pipes to alter, clutch recommendations...the challenge has begun.

I will keep those who respond in the loop once the project is started.
:div20:

I would try and help you out ,but to be honest I know nothing about that sled. I'm sure you won't find a different pipe for it. You can probably change the clutching around and improve there. If I remember right those have a different style clutch on them don't they? What is the stock weights and clutch springs that are in it? What rpm is it suppose to run at? Pockets might be able to help you out with this. He is real knowledgable on all polaris sleds. Send him a pm and ask him.

N2O :augen41:

Regear it and reclutch it. It will take a little studying to get the right clutch set up. Gear it down a tooth or two. That will make it alot snapier but will lose a couple mph on top. For a kid his age I think I would go for the snap.

I do not know why you would want to spend the money to add performance to the star, when a good 340 lite would be readily available. I would recommend to leave the exhaust alone, at the most just have it ceramic coated. Reroute the carb vent lines to the airbox, by putting a fitting in the airbox below the shelf, just above the carb opening. Get a fitting from a 1998 Evolved Indy 500. Make sure the carb is not needing any internal parts, needle valve, etc. Jet the mains up 2 sizes from stock, and leave the needle alone. Have a clean and match done to the cyl, as the fuji engines had horrible casting flash from the factory. Do not have the dimensions changed just a good clean and match, with the transfers and intake done with a bead blasted finish, and the exhaust mirror polished. Have the cyl. head cc'd to see if it is in spec, and if it isn't, have it shaved to bring it to spec. The specs will be in the dealers 1995 service manual, it will give installed and uninstalled cc's. If you can run 91 octane fuel always, have the head shaved an additional .020" after it has been brought to spec. Also replace the rings, or the piston and overbored if needed to bring the cyl to piston clearance to spec. Use only a Polaris piston. Verify the clutch condition, both the primary and secondary, and make sure the alignment is spot on, as well as the belt to sheave clearance set to .010" to .020" with a new belt. Also install a torque stop to the front of the engine, you can buy an all metal one from Polaris, it is priced reasonable. For clutching you will have to tell me what it has now factory, so I can give some recommendations. I can't say that I touched one of those 250's before!!! You could probably have someone cut you a helix for the factory clutch, like dalton or others. You would want something with about 4 degrees more starting angle than it has stock, ideally cut to a full progressive, or to hold the 4 extra degrees for the first inch down the ramp.

Thanks Pockets, good advice.

The OEM primary clutch calibration is weak at best and would benefit from another 750-1000 RPM at engagement. The clutch is a typical 6-bolt cover, 3-fly weight style like the others. The OEM primary spring is Orange part number 7041060; weights are part number 5630325 (10M-R/10-44) whatever that means. Any suggestions for new spring and weights to get more engagement RPMs?

The secondary clutch seems to work pretty well right now. If I can get more power out of it without going through the engine I may get more aggressive with the helix as you mentioned.

I would stay with a similar rate, just more at engagement and shift out. A red/white should be easy to find, #7041150. I would also go to heavier weights with this spring, 10MW. If you do not want to change the weights, just a pink spring #7041065. Without changing the helix, you are shorting yourself the greatest amount of gain. The helix with more starting angle with give quicker upshift out of the hole, by loading the engine a bit more, and making the polaris primary clutch upshift past it's inefficient low ratio. The polaris clutch does not provide as much belt squeeze at low end as say the TRA, but in mid and full shift is very efficient.

Damn!, I wish I had 1/16 of your knowledge pockets.


Jeff_G

NO KIDIN

That sled has the p-90 secondary on it. If the 250 is the same as my sons 340Lite it has a 36.5* helix I believe. The helix style may be the same as a older poo quad. You may be able to get a more aggressive helix in that line. A comet silver/black primary spring with .060 shims will also raise your engagement, and keep the top rate the same as the orange. I actually liked that spring/washer setup in my Indy Trail488 mod better than the red/white poo spring. You could also try a set of the old J {44grams} or M-1 weights {47 grams} these are not bushed and you would probably have to reshim your spyder or add cover bolt plastic spacer washers to push the sheave back to the belt. I would try the red/white with these. These weight will raise your engagement. My son last year {12 yr old} on his 340 Lite was running side by side with me on my 700, 75 mph on my speedo and climbing on a hardpack lake. I would add 48-60 studs after raising the engagement and he will be smiling. 65mph+ should be attainable. Tuning it with you riding it will also through your setups off. He weighs maybe a 1/2 to 1/3 of your weight? If you are confident in his riding I would do side by side testing against your sled, or chase behind him. The 340 would be the way to go. Those motors come on e-bay often

If you are interested in the M1 weights and red/white spring I'll sell the setup for $22 shipped {only to lower 48 states}. All old but only used for testing many years ago.

OK, you ready for some old and odd part numbers for different P-90 clutch helixes? Here you go. All Polaris part numbers.

34' straight - 5131164
38/36' dual - 5131162
38/36/34' multi - 5131163
40/38/36' multi - 5131161

As for the primary springs, Pockets is on the money. Red/white Polaris spring with some heavier weights or a Pink Polaris spring with the stock weights. The nice thing about the P-90 secondary clutch is that you have 4 holes for the spring to go into. 2 on the helix and 2 on the sheave. Same principle as the P-85, just done a little differently. On the IndyLite 340's the secondary is way to stiff for full shift out. I'm sure the Starlite is the same. Soften it up a little bit for more top end, but you may loose some soft snow capabilities due to the lack of power that sucker puts out. Make it breath better, jet it correctly and cut the head for some cheap power. Have fun.

P.S. I played with my nephews Indy Lite 340 and that sucker runs dam good. Racerdave is right. My nephews sled will run 75 mph on a lake all day with his light butt. So more speed is possible out of these little sleds. Also, out of the hole the sled is awesome now. Jetting, carb work, air box work, clutching and 48 studs woke it right up.

:div20: