The fix on the Pro

[RKT]

2) Lifting the cylinder on this engine will change crank case volume which we have found to hurt performance, especially, at the higher elevations..


I have to disagree as The motor was designed as a 600 and the factory race sleds increase crankcase volume any way they can I belive the lack of volume is one of the reasons this motors not in the 160's like the rest

Lifting the cylinder on this engine WILL LESSEN Piston support which WILL increase piston wear and WILL place more stress on the skirt of the piston and the cylinder.

that depends on the piston configuration! But this JMO

So, at, say... 7000ft.... how is that 800 acting? Is it acting like a true 800 or maybe a 600?? It is all relative... your 800cc sled is really a 600cc sled at the higher elevations... food for thought...

As for the piston configuration changing load properties.. sure.. but when you already have a cylinder skirt that is too short and then you raise the cylinder.. that too short skirt gets even shorter, not longer, so there is less piston support--> everytime...

 

[chunkysoup]

As for the piston configuration changing load properties.. sure.. but when you already have a cylinder skirt that is too short and then you raise the cylinder.. that too short skirt gets even shorter, not longer, so there is less piston support--> everytime...

On the "fix kit", when the cylinder is raised by a shim the piston is raised the same amount by changing the pin location. The load will lessen on the cylinder skirts because of the pin location not because of the shim under the cylinders.

 

[RKT]

When the cylinder is raised by a shim the piston is raised the same amount by changing the pin location. The load will lessen on the cylinder skirts because of the pin location not because of the shim under the cylinders.

So, hypothetically speaking... let's say the cylinder is raised .100" and the piston is also raise .100" and the cylinder skirt is .500" too short..
With raising the cylinder and the piston the SAME amount, you have not changed anything in terms of skirt support (it is still .500" too short).. If you raise the cylinder 1" and the piston 1".. same deal.. nothing changes... if you raise the cylinder 1" and the piston .75", then you lessened the cylinder support on the piston..

You can NOT lower the piston at all or it will make contact with the crank wheel. So, no matter how you slice it, there is no way to get more piston skirt support without exposing the exhaust port at TDC....

Not trying to be a nit-pik... just telling it like it is.... at the end of the day, the cylinder skirt will always be lacking full piston support.

As for side loading.. tighter pistons will help drastically in that dept.. again.. IMO, there is NO rod/ratio problem.. many facts to support this as well..

 

[chunkysoup]

So, at, say... 7000ft.... how is that 800 acting? Is it acting like a true 800 or maybe a 600?? It is all relative... your 800cc sled is really a 600cc sled at the higher elevations... food for thought...

As for the piston configuration changing load properties.. sure.. but when you already have a cylinder skirt that is too short and then you raise the cylinder.. that too short skirt gets even shorter, not longer, so there is less piston support--> everytime...

So, hypothetically speaking... let's say the cylinder is raised .100" and the piston is also raise .100" and the cylinder skirt is .500" too short..
With raising the cylinder and the piston the SAME amount, you have not changed anything in terms of skirt support (it is still .500" too short).. If you raise the cylinder 1" and the piston 1".. same deal.. nothing changes... if you raise the cylinder 1" and the piston .75", then you lessened the cylinder support on the piston..

You can NOT lower the piston at all or it will make contact with the crank wheel. So, no matter how you slice it, there is no way to get more piston skirt support without exposing the exhaust port at TDC....

Not trying to be a nit-pik... just telling it like it is.... at the end of the day, the cylinder skirt will always be lacking full piston support.

As for side loading.. tighter pistons will help drastically in that dept.. again.. IMO, there is NO rod/ratio problem.. many facts to support this as well..

Im not saying the piston will be more supported. You are right, the piston will have the same support as stock as it does with the fix kit. The fix kit uses a properly sized piston as does your kit but the difference is the fix kit changes the load properties by moving the wrist pin.

Their idea is that size of the piston and the load property of the piston was the problem so they moved the wrist pin and kept tighter tolerances on their pistons. Since they moved the wrist pin they had to raise the cylinders to compensate.

Your idea is to just use the right size piston. correct? maybe a little different designed crown for better performance with your head?

 

[chunkysoup]

2) Lifting the cylinder on this engine will change crank case volume which we have found to hurt performance, especially, at the higher elevations..


I have to disagree as The motor was designed as a 600 and the factory race sleds increase crankcase volume any way they can I belive the lack of volume is one of the reasons this motors not in the 160's like the rest

The engine with more case volume will have more potential for higher horsepower with no additional mods. FACT

the old saying, there is no replacement for displacement, comes to mind.

 

[RKT]

Im not saying the piston will be more supported. You are right, the piston will have the same support as stock as it does with the fix kit. The fix kit uses a properly sized piston as does your kit but the difference is the fix kit changes the load properties by moving the wrist pin.

Their idea is that size of the piston and the load property of the piston was the problem so they moved the wrist pin and kept tighter tolerances on their pistons. Since they moved the wrist pin they had to raise the cylinders to compensate.

Your idea is to just use the right size piston. correct? maybe a little different designed crown for better performance with your head?

No, there is much more going on with this kit than meets the eye

Also, relocating the pin upwards or downwards does nothing for side load altering...

 

[RKT]

The engine with more case volume will have more potential for higher horsepower with no additional mods. FACT

the old saying, there is no replacement for displacement, comes to mind.

With all due respect... NOT A FACT!

and case volume is NOT a factor in displacement. Displacement is referencing the total swept volume (ie cylinder) again.. case volume is NOT a factor in displacement calculation.

 

[Norway]

Piston to cylinder wall area

I believe the added support from the piston in the fix kit comes from a longer piston having more square inches in contact with the cylinder wall, as well as a tighter clearance.

And this holds true during most of the revolution. When passing BDC the piston will stick below the cylinder for a while, but above that you have the added support of a larger area. And I would imagine the compression stroke well over and the pressure on the piston (sideloading) gone when the exhaust port is 50% open, hence you have more support when you need it.

I to have experienced harder pulling and more trackspeed going a bit past 8000rpm, only problem is it's close to the rev limit and this will give you more cut-outs.

As I've said before, poo will not admit there is a problem or hand out better hardware unless they are forced to. They will try to improve it for sure, but the lemons sold will be on their own once the warranty expires..
With the lovely light pro chassi, talk about a fly in your Chardonay..

I asked on their fb page for any news on 800cfi reliability, guess how many seconds that line was there??

 

[chunkysoup]

With all due respect... NOT A FACT!

and case volume is NOT a factor in displacement. Displacement is referencing the total swept volume (ie cylinder) again.. case volume is NOT a factor in displacement calculation.

Sorry, I agree I was just using it as an example. Case volume does not affect the displacement. But an engine with more case volume will have the "potential" for more horsepower. thats the problem with engineering an 800 engine based off a 600 bottomend. there is not enough case volume.

 

[beamslayer]

Kelsey is the pro kit the same as the ski doo kit or should I say are the pistons the same ?
What is gained by using your head compared to the cheater head if any ?
Are your pistons mfg here in the states or over the big pond ?
Can I use my P.A. head and your drop in kit or is your kit designed just for your head ?
How is the 858 kit working that went north ?

 

[RKT]

Case volume does not affect the displacement. But an engine with more case volume will have the "potential" for more horsepower. thats the problem with engineering an 800 engine based off a 600 bottomend. there is not enough case volume.

Again,, with all due respect.. not true..

Kelsey is the pro kit the same as the ski doo kit or should I say are the pistons the same ?
What is gained by using your head compared to the cheater head if any ?
Are your pistons mfg here in the states or over the big pond ?
Can I use my P.A. head and your drop in kit or is your kit designed just for your head ?
How is the 858 kit working that went north ?

Feel free to call anytime to discuss any of the products...

I just entered this thread to clear up the miscomceptions regarding the RK Tek kits.. It has now went passed that point and that was not my intent..

It is just unfortunate what some will believe is happening inside an engine and what REALLY changes when certain alterations are performed vs. what is really happening or NOT happening... Very unfortuante...

I am out of this one, for now..

 

[AKSNOWRIDER]

I am going to chime in here..just so the average guy can make an informed decision...a longer rod will lessen skirt loading...period..been proven time and again over the years..it will also move more air thru the motor for a given case/cylinder volume..again been proven for years(case in point..when polaris changed this motor from a 6 to a 8..they lengthened the rod...both to lighten skirt loading due to the bigger/heavier piston, and to help with case /cylinder filling which is a by product of a longer rod..) now is it the fix all? no its not, but every engine designer/builder spends a lot of time /work coming up with a rod ratio that balances out bore/stroke/breathing capacity. normally to lessen pressure on the skirts with a longer rod, you would not move the cylinder, but redesign the piston to move the wristpin up in the piston, which concentrates the side loads closer to the barrel of the piston and off the skirts..
Kelseys tigher pistons will lighten the skirt loading..but the mono block cylinders due to the compact design and the placement of the powervalves lack good equal coolant flow around the whole cylinder, which can (and I am sure does) lead to cylinders going out of round as they get hotter and hotter, which could cause issues with too tight of a piston/bore ..as for the dome design on the piston making more power..most likely not measurable on a dyno..but the tighter wall clearences should make for better ring seal which should help power...personally, I would love to see a builder come out with a .250 longer rod, a new forged piston with the wristpin moved up .250 as well as mover over closer to the intake sside by.010- .015 and a .004 to .006 wall clearence..I think the breathinig improvements when coupled with the right dome shape would add 10+ hp, and I think it would end the skirt issues we are seeing...

 

[chunkysoup]

I believe the added support from the piston in the fix kit comes from a longer piston having more square inches in contact with the cylinder wall, as well as a tighter clearance.

I could be wrong... but i dont think they changed the height of the piston at all. I thought they simply moved the wrist pin location. Changing the height of the actual piston would change the port timing. Would it not?

 

[AKSNOWRIDER]

With all due respect... NOT A FACT!

and case volume is NOT a factor in displacement. Displacement is referencing the total swept volume (ie cylinder) again.. case volume is NOT a factor in displacement calculation.

kelsey, I have to disagree, case volume/ cylinder bore/stroke and even rod ratio and crank throw edging all play a role in how much air a motor can move..and thus how much power it can produce......

 

[chunkysoup]

Again,, with all due respect.. not true..



Feel free to call anytime to discuss any of the products...

I just entered this thread to clear up the miscomceptions regarding the RK Tek kits.. It has now went passed that point and that was not my intent..

It is just unfortunate what some will believe is happening inside an engine and what REALLY changes when certain alterations are performed vs. what is really happening or NOT happening... Very unfortuante...

I am out of this one, for now..

Im not trying to start a pissing match by any means. I am simply trying to get the truth out there. So what you are telling me is that you could take a stock engine and run it next to the same engine with the case ported and the ported motor would make no more power? Then how do turbos work? Isnt the idea to get as much fuel and air possible into the combustion chamber as fast and efficiently as possible to make more power? If im out of line about this someone needs to set me straight.

 

[RKT]

Im not trying to start a pissing match by any means. I am simply trying to get the truth out there. So what you are telling me is that you could take a stock engine and run it next to the same engine with the case ported and the ported motor would make no more power? Then how do turbos work? Isnt the idea to get as much fuel and air possible into the combustion chamber as fast and efficiently as possible to make more power? If im out of line about this someone needs to set me straight.

OK, let's use some hypothetical (unrealistic) numbers/examples and try to get this more clear..

IF you have 10 secs to fill a 100 gallon pond (case)with water and you have fixed water supply (intake track) flowing at 1 gallon/sec... You will fill the pond with 10 gallons in the 10 seconds.

Now, you increase the pond size (case) to 200 gallons... and you still have the same inlet time (10 sec) ,supply (intake) and rate (1 gal/sec)..

Did you get anymore water in the pond?

 

[Norway]

With all due respect... NOT A FACT!

and case volume is NOT a factor in displacement. Displacement is referencing the total swept volume (ie cylinder) again.. case volume is NOT a factor in displacement calculation.

Hmmmm... Can of worms anyone?? LOL.

Case volume plays a factor in power and to small volume CAN hurt performance. But this is where the black-art comes in, as you can hurt performance also by the shape of things in the case. We are talking airflow and aerodynamics here.

On this particular engine I know one very reputable shop that complains about case volume, so what am I as a dumb consumer to believe?

Anyway, when throwing facts around on the internet, this forum has many users giving praise to the fix kit for added performance. Go figure.

My only beef in this matter is I'll be more scared of my "new" pro throwing a piston next winter than my Price 1029 big bore triple...

 

[Norway]

I could be wrong... but i dont think they changed the height of the piston at all. I thought they simply moved the wrist pin location. Changing the height of the actual piston would change the port timing. Would it not?

For sure there piston is taller (above the wrist pin), that is why they have a shim as part of their kit. To get the port timing correct again.

Is my memory incorrect on the whole piston being longer??

 

[RKT]

Hmmmm... Can of worms anyone?? LOL.

Case volume plays a factor in power and to small volume CAN hurt performance. But this is where the black-art comes in, as you can hurt performance also by the shape of things in the case. We are talking airflow and aerodynamics here.

On this particular engine I know one very reputable shop that complains about case volume, so what am I as a dumb consumer to believe?

Rune.. Correct... but you ride from sea level to 3000ft.. Do you think an engine running at sea level requires the same case volume as the same engine running at 5000ft-10,000ft?

So, it could very well be true that this engine running at 1000ft would benefit from added volume and at the same time, the added volume would hinder at higher elevations?? Wouldn't you agree??

Totally correct on aerodynamics within the engine.. Adding a spacer is NOT the same as porting an engine. All you did was add volume in the lower end.. This MAY upset airflow and MAY aid it.. This is why the earlier "FACT" Statement is simply not a FACT.. There are other variables at play here.

In order to take advantage of increased airflow/volume, you MUST have added "other" devices that can supply more air (ie turbo, pipe, reeds etc. etc) ..

To simply add more volume (shim) and add no other "piece" that would actually increase airflow--> would USUALLY be counter-productive UNLESS the engine actually was deficient in case volume to begin with. Which is up for debate and largely dependent on elevation.

 

[chunkysoup]

I could be wrong... but i dont think they changed the height of the piston at all. I thought they simply moved the wrist pin location. Changing the height of the actual piston would change the port timing. Would it not?

Sorry guys, I was wrong. I called Shaun and they did add material above the wrist pin. Not just move the wrist pin. So yes there will be less support on the piston skirt at BDC but the piston should be supported like Norway said with more surface area up in the cylinder. The port timing does not change because of the shim and the skirt doesnt control any lower ports in the cylinder.