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Discussion Starter · #1 ·
i tried a 01 thundercat 1000 last year and ended up selling it and going back to Polaris (i have always owned polaris). I bought a 2000 XCR 800 (all stock). Now im starting to modify it for this winter. so far i have wiseco pistons, billet heads, tripple pipes(stock silencer), cylinder porting, delta 3 reeds, and of coarse studed track.

I plan on doing a little trail ridding and mostly lake racing(i got a pesky f7 to beat up on).

any ideas on cluthcing, carb jetting, gearing?

any other little tricks to help it go fast?

chassis set-up for better weight transfer?

i think it should be about 180hp and easily break 100mph in 1000ft. i was thinking the motor will be spinnig higher rpm so maybe drop the gearing down lower for more acceleration???

thanks for any info
 

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01thundercat said:
i tried a 01 thundercat 1000 last year and ended up selling it and going back to Polaris (i have always owned polaris). I bought a 2000 XCR 800 (all stock). Now im starting to modify it for this winter. so far i have wiseco pistons, billet heads, tripple pipes(stock silencer), cylinder porting, delta 3 reeds, and of coarse studed track.

I plan on doing a little trail ridding and mostly lake racing(i got a pesky f7 to beat up on).

any ideas on cluthcing, carb jetting, gearing?

any other little tricks to help it go fast?

chassis set-up for better weight transfer?

i think it should be about 180hp and easily break 100mph in 1000ft. i was thinking the motor will be spinnig higher rpm so maybe drop the gearing down lower for more acceleration???

thanks for any info
What pipes and whose porting? That will help answer your questions better.
 

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Discussion Starter · #3 ·
yellowstorm800 said:
What pipes and whose porting? That will help answer your questions better.
dynoport pipes, speedwerks/hot seat trail porting, speedwerks/hot seat billet heads.

its getting harder to find companies making parts for this sled so you just gotta go with what is available or get lucky buying used parts.

i had considered buying a new sled but the price verses performance isnt there? $8,000+ for 150hp sled? i will have about $5,000 into this (clean)old sled and smoke just about everything that isnt a full race sled.
 

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You need to clutch for the RPM that the porting is designed for. Mine runs best at 8650 - 8700 on a calibrated tach and my XCR is also ported. I run an alomond round with 10-62's. The secondary you will have a lot of different options. Mine seems to really like a Dalton 52/44/36 full progressive with an EPI black.
For traction, use at least 192 studs with about 7/16" penetration. Also take out your rear transfer blocks and you shouldn't have to many traction issues.
 

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are you in mn? in all honesty i think speedworx would do a decent job on porting but for alot less money you can do the porting yourself with a racelogic template or i can do minor clean up so it would be none ported just run a little better.

xcr1250 and patriotic inovations can also do a very good job of aggressive porting for more bang for the buck than any big shop.

on a side note, battlestorms xcr 800 has beat many ported and piped xcr's in drags. after playing with pipes i would stick with the stock ones. you already have a traction problem, adding hp isnt going to fix that.

heel clickers or dragon flys work amazing in the xcr and after seeing them in side by side runs compared to other weights without a doubt i am getting them and recomend them. most of the guys seem to like the 22-40 gearing for aggressive drags and trail riding.

a stock xcr with 22-40 gears and traction will smoke an f-7. a piped and ported xcr with heads and bored carbs will get smoked by a stock f-7 if you dont do something about traction. instead of pissing money on aftermarket hp buy a nice 1" hacksaw track and about 192 studs.

i did my own porting and cut the stock heads, bored carbs and advanced the timing and could pull the same clutch setups and gearing that the guys who spent 600+ on porting and a couple hundred more on heads.

I would also work on wieght. force = mass accelerated. so to accelerate more mass equaly to less mass you need more force. for a couple hundred dollars you can get a light weight hood, so on drag days you can put the hood on and drop 30 lbs. no lights, speedo tach or anything, just a light wieght hood and windshield. there are other ways to shed wieght also.
 

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Discussion Starter · #7 ·
yellowstorm800 said:
madcow said:
xcr1250 and patriotic inovations can also do a very good job of aggressive porting for more bang for the buck than any big shop.
[thumb]
thanks for the info guys.

its funny what you recomended for the sled. i should have said it was "mostly stock" cause it has a 1" camoplast track with 192 studs that have 1/2-7/16 over the lug. and it has 10-62 weights in the primary and a black/white stripe spring. and some of the rear suspension mounting points/adjustments have been changed from stock so i think the previous owner probly was racing it. it did have the stock pipes and stock jetting though.

i have already spent the money on the parts i listed: pipes, heads, reeds, porting, pistons.

i decided to keep the stock silencer to keep it quite. but in know i could shave 10lbs with an aftermarket one in the future if need be.

as far as tuning the clutchs i cant tell till i get it on the snow, but was looking for a staring point or what others are running.

and for porting i have always cleaned up the casting material on my snowmobile engines when they are apart but beyond that i dont know enough to raise ports to work at a certain rpm with certain pipes and figured id leave it up to the pros.

i think i will spank the f7 stock but just want to make sure. i know the f7 is 140hp and 450lbs and the xcr is easliy 100lbs heavier so shedding weight would help a lot too.

thanks again.
 

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I would start out with the clutching that I said in the earlier post. That should get you a close starting point. Like Madcow said, alot of guys like the 22/40 gears but I like it a little bit taller. I haven't found what works the best yet but I think I will be running around a 23/40 this year.
 

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i personally like tall gearing, but i dont do much drag racing either. running a little lower gearing will help the sled run more consistant in different conditions.

for clutching some of us are running custom cut helix's like 55-30 or whatever, i have a 54-48 that will pretty much shut any sled down that is under 250 hp. but i want to try to make it work?!

with the dragon flys or two speed heel clickers the stock helix works amazingly well!

make sure you have a torque stop, play with gutting the air box.

i drag raced some f-7's in short drags with 25-37 gears and did well. gear as tall as you can without hurting accelration.
 

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Discussion Starter · #10 ·
here is a pic of my sled so far.

i told the f7 owner some of what i was doing to my xcr800 so i think he is a little worried and will be doing some mods too

this will help to settle the debate of what's better less weight(f7) or more hp(xcr800) this could get interesting!!!

we plan on hitting some of the local radar runs this year for fun maybe i'll see you around?




madcow said:
i personally like tall gearing, but i dont do much drag racing either. running a little lower gearing will help the sled run more consistant in different conditions.

for clutching some of us are running custom cut helix's like 55-30 or whatever, i have a 54-48 that will pretty much shut any sled down that is under 250 hp. but i want to try to make it work?!

with the dragon flys or two speed heel clickers the stock helix works amazingly well!

make sure you have a torque stop, play with gutting the air box.

i drag raced some f-7's in short drags with 25-37 gears and did well. gear as tall as you can without hurting accelration.

torque stop? is the stock rubber one fine or do i need aftermarket?

anyone run harder motor mounts? what brand recomend?
 

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The torque stop goes on the left front of the motor. It is a very good idea like Madcow said. These motors like to twist alot in the chassis.
 

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the hard mounts get annoying on the trail, they make the foot wells and handle bars buzzy.

for the radar run you might have a better chance with hp, but making speed is not easy, I know many people who took a sled down the radar track and did 100 mph, then added pipes porting clutching and tons of other stuff to only go 100 mph. it takes time to build speed what they didnt realize is that they were getting there alot quicker even though they went the same speed.
 
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