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question on durabilty kits cfi 800?

wildcard28

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Dec 18, 2007
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Of vids and research Ive done on these kit of like last vid I just watched from Bikeman Performance. Why is the length and support of the piston only added above the wrist pin and the skirt length not lower skirt not lengthened or modified?

Wouldn't that make the piston skirt drop farther down into the case and have more of the side of the piston and skirt exposed since the spacer is added and the cylinder skirt is raised? or would if the bottom of skirt was lengthed would it come in contact with the crank not sure how close the stock pistons would be to the crank in this area.

The cyl skirt raised would seem to add more fuel into the case and add hp but is it really worth it or should a guy just add Better than stock crappy piston and put in better cast or forged? I not a fan of the finikyness of the forged piston I currently have the topend of my sled ready to go back together and I for the rest of the season ordered SPI moly stock replacement pistons, but in off season debating whether a Fix Kit is worth it or just Put in a pet of RKtek direct replacement pistons. Kelsey and I had a fallen out along time ago on another deal that was slowly resolved, but I not a grudge holder and that doesn't take away from the fact that he does seem to make a pretty impressive product.

buddy has the 858 kit and that's a monster. I cant afford one of those just Id rather reliability and some smaller sensible mods to my engine and focus on the more expense in making the handleing, flickability and comfort of the sled.

Thanks, Wildcard
 

Octanee

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I could be remembering wrong, but the connecting rods and pistons get lengthened ontop as to the bottom skirts, they nearly bottom out into the crank case, so lengthening them that way won't work. But adding length ontop has the same effect as well as far as preventing any piston rocking in the cylinder while keeping stock rod length.

A local shop here has done many fix kits, he's seen too many blown polaris's, he's done many fix kits, however he puts many kits with the cast pistons in, he figures the forged wiseco are a greater piston but people want to pull and go, forged need to warm up before going and has had customers cold seize their engines, I'm sure we have all seen it, guys after a lunch for a hour, fire up their sled then go pull a hill wide open. After having the kit in he doesn't see them failures anymore.
 

wildcard28

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Dec 18, 2007
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Buddy and I ride with his boy and nephew young preteens and they get stuck a lot more than us. Lol just learning but most cases went conservative rather than throttled out which is good not getting over there head no matter the situation we seem to be stopping a lot more often shutting sled off walking over getting a sled unstuck or ski pulled out and on everyone goes so don't get time after a few minutes or 15-20 etc to just start and wait youll get left behind and before ya know it someone may or maynot be turning around for ya. this I think is the pro with a forged piston. like shop owner around here told me other day even when we get stuck and the tunnel cooler cool down faster since they are barried in snow and sled is in a ****ty spot where you need to start and WOT to get out who has time or situation to set and wait for water temp to even out on the guage before you get into it.

We all warmup the sleds and let them run as we are unloaded and gearing up then helmet up gloves and tether on and off we go that not the prob

its the continuous stop and go thru the day whether it 1/2hour or just matter of minutes this seem to stun or cold seize a forged piston

So can piston would work better in this situation or style of riding, Which piston would be recommended for this whether its combined with a Fix Kit or stock replacement?

Of research Ive done seem oil to the cylinders and piston is a big issue you watch the Paasco vids on youtube about the poorly vented Oil Caps and turning the oiler up which mine has already been turned up and adding oil to you tank of fuel are All great Ideas that I will be doing regardless, already ordered a 15 XM Etek Oil Cap and will be adding fuel to the tank I believe all sleds would benefit from this. My Rev is Oil injection Delete so that's never been a prob.

Thanks Again, Wildcard
 

Octanee

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Buddy and I ride with his boy and nephew young preteens and they get stuck a lot more than us. Lol just learning but most cases went conservative rather than throttled out which is good not getting over there head no matter the situation we seem to be stopping a lot more often shutting sled off walking over getting a sled unstuck or ski pulled out and on everyone goes so don't get time after a few minutes or 15-20 etc to just start and wait youll get left behind and before ya know it someone may or maynot be turning around for ya. this I think is the pro with a forged piston. like shop owner around here told me other day even when we get stuck and the tunnel cooler cool down faster since they are barried in snow and sled is in a ****ty spot where you need to start and WOT to get out who has time or situation to set and wait for water temp to even out on the guage before you get into it.

We all warmup the sleds and let them run as we are unloaded and gearing up then helmet up gloves and tether on and off we go that not the prob

its the continuous stop and go thru the day whether it 1/2hour or just matter of minutes this seem to stun or cold seize a forged piston

So can piston would work better in this situation or style of riding, Which piston would be recommended for this whether its combined with a Fix Kit or stock replacement?

Of research Ive done seem oil to the cylinders and piston is a big issue you watch the Paasco vids on youtube about the poorly vented Oil Caps and turning the oiler up which mine has already been turned up and adding oil to you tank of fuel are All great Ideas that I will be doing regardless, already ordered a 15 XM Etek Oil Cap and will be adding fuel to the tank I believe all sleds would benefit from this. My Rev is Oil injection Delete so that's never been a prob.

Thanks Again, Wildcard


yeah It certainly depends, good to hear you guys do a good solid warm up before riding. If your sled sits for a hour, yeah it should probably idle for a bit. a half hour, depends on the air temp, I certainly wouldn't pin it immediately. probably good to let idle for a minute anyways. Short get unstuck's up to ~10-15 mins, probably not a problem. I think the other half of the "fix kits" come with SPI cast pistons, seems like most of the kits nobody has issues with after the fact for the most part between the 2. Biggest issue with forged is when the engines dead cold the piston will expand faster than a cast supposedly and if you lay on it, it can cold seize. if your engines/cylinders have heat in the walls, you should be fine.

Today I was in about waist deep powder, I run a turbo, I thought my buddy got stuck so I went to do a half turn around and he came up on me, opted the easiest was to man handle my sled back straight the way we were going, it sat off for ~15 mins, I fired it up and it idled about 30 seconds and away I went into boost right away, engine was still about 113F or 45C ish.
 
I'm a big fan of letting it idle a moment after any shut down ,beer break, stuck after a hard climb. I think of hot motor the thermostat wide open and tunnel coolers sticking out in the cool air or snow , so I start and idle a moment before moving on out. My forged Pistons have over a year on them now.
 

wildcard28

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Dec 18, 2007
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Thanks for all the Replies guys, I ended up goin with the SPI pistons I ordered a set that was supposed to be here middle last week to get ready for a ride last weekend and they got all lost in shipping we thought so was gonna purchase the Wiseco piston from local shop gut day after I ordered them guess what showed up, Figures the SPI Tmolly pistons that I already ordered. Lol

Rather than buying a second set unsure if I could return the first I stayed with the first.

Got the sled almost back together, I am rerouting the oil line from the tank to the pump a thread I found on Backcountryrebels.com pretty interesting point, ordered the XM vented cap also. and gonna run some oil in my gas tank from now on.

Like Octanee said I did realize we usually let the sled idle for a short bit after we get it ready to ride out of a stick or rolled back over or on a ski pull I ususaly start the sled as I'm putting my helmet/goggles back on along with reattaching my tether so doesn't seem like along time but probably enough for the coolant to flow and stabilize. even if I have to Wick it pretty hard to get out it usually is just a couple seconds as sled pops back out or up on show and I still let is idle for a few rather than just holding the kill switch.

Thanks, Wildcard
 

XCaSSAULT

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Highly recommend the “trs thermostat bypass upgrade” google that and you’ll find the thread. 99 degree t-stat in a exterior housing that creates basically 2 loops for the coolant where the hot and cold get mixed. Instead of having the hot cold get mixed in the motor.

Without bypass temps are 128-140 and after a brief stop and restart jump to 165 and fall to 108 in about 90 seconds

With bypass temps are 104-118 and after brief stop and restart jump to 140 and fall to 104 in about 20 seconds.

You still need to let the temp settle before gunning the throttle but it only takes 20sec compared to 90sec. Start sled, put your helmet on and it’s ready! Faster warm up times in the morning as well.

Not to mention a noticeable increase in throttle response running at 104 and longer engine life. The fuel map and timing are in sync at sub 120! Kinda all over the place above that. Colder is better. Polaris finally learned this on the axys motor
 
Last edited:

wildcard28

Well-known member
Dec 18, 2007
1,477
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Clarkston WA
s375.photobucket.com
Highly recommend the “trs thermostat bypass upgrade” google that and you’ll find the thread. 99 degree t-stat in a exterior housing that creates basically 2 loops for the coolant where the hot and cold get mixed. Instead of having the hot cold get mixed in the motor.

Without bypass temps are 128-140 and after a brief stop and restart jump to 165 and fall to 108 in about 90 seconds

With bypass temps are 104-118 and after brief stop and restart jump to 140 and fall to 104 in about 20 seconds.

Not to mention a noticeable increase in throttle response running at 104 and longer engine life. Colder is better. Polaris finally learned this on the axys motor

I was reading a thread on this but was kinda unclear on what you actualy get for the $28 and what actual pieces ya get and hardward needed would be nice to see a detailed install of vid, not sure if its out there, I did a thermostat bypass on my Rev I seen Sledhead Racing do so I done this as I was installing his ported trail torquer kit on my Rev, Man that motor ran, also run cooler

Thanks, Wildcard
 

XCaSSAULT

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All you really need is the t-stat/housing which is part number 509000499 at partspitstop.com its $29.99. That gets cut in on your top hose that goes to your existing t-stat housing. I was able to just flip the hose (red arrow) and it worked perfect.

Then you need a 1x1x3/4 T ski doo part number 509000372 $7.99. Maybe any abs T of the same size would work but I wouldn’t chance it. That T gets cut in on on your line that goes from tunnel cooler to bottom of motor.

Then u just need a tight 90 degree bend piece of 3/4 radiator hose and a 3/4 rubber cap and all the 7/8-1-3/4 hose clamps to clamp it all together, and a little heat/reflective tape to put on the t-stat housing as it’s pretty close to the exhaust. Should be able to find all that stuff at auto part store. Some guys use quick clamps or heat shrink clamps but I didn’t trust them clamps. Oh and you gut your existing-stat and reuse the outer metal to hold the rubber gasket in place.

All said, easy and prolly be done for around $50. In my opinion best $50 you could spend on your sled. I joke with my buddies that my polaris has ski doo and arctic cat parts on it to make it reliable! Lol (pistons for fix kit are same spec as cat m8)
 

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rags319

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Thinking about this also. So you take old t-stat out and do you need the cetian size washer to restrict coolant in its place. Referring to original thread this is talked about.
 

XCaSSAULT

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Yes take old stat out. No need for different restricting washers, I think they were talking about only using a restrictive washer and nothing else.

It wouldn’t be a good idea to just run no stat because that will open the motor to a high chance of cold shock (side note, my 97-1/2 xc700 came from the factory with no stat and it’s made it 14,000plus miles with only 2 top ends)

U can’t just throw old stat away because there needs to be something to hold the rubber gasket in there. You could find a washer the same diameter as the stat but why? Just gut and go.
 

rags319

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Yes take old stat out. No need for different restricting washers, I think they were talking about only using a restrictive washer and nothing else.

It wouldn’t be a good idea to just run no stat because that will open the motor to a high chance of cold shock (side note, my 97-1/2 xc700 came from the factory with no stat and it’s made it 14,000plus miles with only 2 top ends)

U can’t just throw old stat away because there needs to be something to hold the rubber gasket in there. You could find a washer the same diameter as the stat but why? Just gut and go.

Ok. So use the old t-stat housing but gut the spring and stat part correct.
 

XCaSSAULT

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Ok. So use the old t-stat housing but gut the spring and stat part correct.

Correct. Just take a couple of pliers after it and give er hell. Then straighten the outer reused piece back out, put the rubber on and ram it in!:eyebrows::bowl:
 
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