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Discussion Starter #1
I was just at a vintage snowmobile race at Melgeorge's resort on Elephant Lake in Northern Minnesota. I think it's definitely something I want to get into. I brought 3 sleds up to it.

1. 71 Chaparral Firebird 440- raced
2. 72 Chaparral firebird 400- raced
3. 71 Ski Doo Olympique 299- Show

I was put against modified sleds(like I had a chance!) and was obviously slower. I thought they would have stock and modified classes. There were 57 racers(place was packed). It was great to see so many sleds that were still running, and in good shape.

Next year, I want to go and kick some A$$!!! I want to modify a sled that I will be getting in a couple of weeks. The guy I am buying it from said that it is a strong sled. "Lifts the skis off the ground," he said. I want to modify this sled to the bring of destroying it. I want to pull every bit of horse power out of this thing.

My question is, with limited expense, what can I do to trick this ride out? Does anyone know where I can get some pipes for this sled? I want to look for race pipes. I also want to do anything I can to the motor, and chassis.

Thanks for the help! I want to dish out a little A$$ whoopin next year.

The meet was great, anyone in the area should come and check it out!

Thanks everyone!!!!!!!!

D
 

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these are some oldschool tricks that my high school shop teacher told us about his sleds when he was a broke kid

port and polish the intake and exhaust

advance the timing

run as high an octane as you can, race gas, aviation (100 low lead) or drop a bunch of moth balls in the gas tank

oh and of course you'll have to work on the track unless its already held together with c bars
 

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Discussion Starter #4
I'm going to be getting a 1976 Yamaha Exciter 440. Pretty nice shape too.

How do you port and polish the intake and exhaust?
 

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If you really want to win that bad NOS it. It will be on the brink of destruction everytime you run it, but you will fly. My girlfriends dad has an older El-Tigre that used to run Nitrous, not him but the previous owner, guy said it used to fly. Now it sits in her dads basement becuase it won't run. But I doubt he ever lost.
Wayne
 

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your 72 Chaparral firebird 400 do you have a spare set of tail lights for it
is so i am looking for a set

also plane your heads can be done with a belt sander
 

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Originally posted by niscola@Mar 16 2004, 12:57 PM


run as high an octane as you can, race gas, aviation (100 low lead)  or drop a bunch of moth balls in the gas tank

What may I ask do the mothballs do for the gas?
 

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for the port and polish, take sandpaper (or a dremel tool) to the intake and exhaust ports, make the ports as big as possible, your goal is to have them match the size of the manifold,

but most importantly get rid of all the casting marks and imperfections, make it as smooth as possible

the moth balls contain alcohol which burns hotter and cleaner (but race gas, or octane booster is probably prefered)

also i'd take the exhaust manifold off and let that dip in varsol for a couple days, then pass a rag through it to get rid of all the crap

and yes, planing the cylinder head is a great idea, raising the compression ratio will give you lots of extra power
 

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Discussion Starter #9
I'm getting goose bumps just listening to all of this. Now, I suppose I will have to go to a richer jet doing all of these improvements, correct??? I mean, it sounds like a little bit of work, and I'd like to keep it running.

I think maybe I'll stay away from NOS. Although I would like to see how it would go.

What about pipes? Does anyone know where I can get some cheap race ones? I can probably modify almost any pipe to go on there. Looking for something fairly cheap. But in no hurry, this is definitely going to be a summer job.

Thanks guys! Keep it coming.

D
 

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Alot of the info that has been posted here is pretty general. There is much greater detail you have to go into when porting, shaving heads, etc. Porting differently up or down changes certain things. Shaving the heads a certain amount will require you use higher octane fuel, even race fuel. Make sure you read up.

Also, clutch setup and gearing is a huge factor to deal with when racing, probably most important.

Here's a great web page with alot of info reguarding 2-stroke performance: http://www.hpt-sport.com/direct.htm
 

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There is lot to building a race motor. You need to get just the right compression ratio, the right squish clearance and width, you just dont go and shave a head. You might cause more harm than good. Pipes will be a big factor. Aaen still makes pipes for old sleds. You might want to check them out. The ports can be enlarged but there again if you do not know what you are doing you can cause more harm than good. As for the octane you have to have the higher compression ratio to make more power with the higher octane fuels. I would say you need a 16.3 to 1 ratio then you can run VP C-14 fuel. I would stay away from the moth balls.
 

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Discussion Starter #14
Doing both DRAGS and ovals.
 

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For drag racing use the lowest octane available that is not oxygenated. You are hard pressed to detonate a motor in 500 feet [grass].
 

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Discussion Starter #16
Why do you want to use thew lowest nonoxygenated octane available?
 

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I've got some twin pipes off a 1975 GPX 433 ..... and other stuff gears , chain and clutch ,and some motor parts . The GPX was a factory racer . Let me know if you need them
 

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Discussion Starter #18
What would you be looking for on those? I'm not sure about the pipes( I'm looking for the skinny race ones) but I might be interested in the gears and clutch and motor parts.

D
 

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i've got a 640cc skidoo engine that would fit in my colt, all it would need is a custom exhaust and an hd carb

i think that it could whoop some ###, the sled weighs nothing...
 

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The 640 cc engine was more of a work engine, but it might work!
 
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