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0.250" compression height w/shim

Brock, Look at the photo of Gen 2 piston along with PRO/AXYS and the ring closure/pin (pin being in the center of the ring groove) and compare with Weisco when you get them and this is what I am talking about. The Weisco that I will forward along the photos of will show the scuffs and unusual ring wear at the closure area. I think due to this type of ring end, it causes the ring end to flex or deform slightly causing the issue that I seem to be seeing and in my case, going back to Polaris Pistons and for fix-kit (shim plate) Arctic or Sno-X (arctic aftermarket) so far I have seen no issues of the past scuffing. I will be endevoring to measure the offset (or not) of the Arctic pistons as I do not know!? Anyone else know that answer here? Again, asking which way did Polaris offset the piston pin,,, pin to the front (exhaust side) or pin to the rear (intake side)???? I will be measuring this when I get to the mill and can chuck a piston in the mill table vice and get the dial indicator on it.
gtwitch in wyoming
 
Brock said:
Working towards the same compression height as stock Polaris with shim and without yes yes :D
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When do you expect dyno results? Will the runs show up as DTR articles?
 
George A Twitchell said:
Brock, Look at the photo of Gen 2 piston along with PRO/AXYS and the ring closure/pin (pin being in the center of the ring groove) and compare with Weisco when you get them and this is what I am talking about. The Weisco that I will forward along the photos of will show the scuffs and unusual ring wear at the closure area. I think due to this type of ring end, it causes the ring end to flex or deform slightly causing the issue that I seem to be seeing and in my case, going back to Polaris Pistons and for fix-kit (shim plate) Arctic or Sno-X (arctic aftermarket) so far I have seen no issues of the past scuffing. I will be endevoring to measure the offset (or not) of the Arctic pistons as I do not know!? Anyone else know that answer here? Again, asking which way did Polaris offset the piston pin,,, pin to the front (exhaust side) or pin to the rear (intake side)???? I will be measuring this when I get to the mill and can chuck a piston in the mill table vice and get the dial indicator on it.
gtwitch in wyoming
Click to expand...
I'll post a pic for you when I get them as I know what your talking about .
Powaton said:
When do you expect dyno results? Will the runs show up as DTR articles?
Click to expand...
We will Dyno them for sure as we need to see were the power and gains made anyways .
Won't be till way cooler weather though .
 
George A Twitchell said:
If I have read most of Indy Dan's and understood those writings, what you guys are saying is basically just what Dan has said also, that being, to get away from longer compression height and back to stock pistons and maybe find better tolarences (thghter) and pay attention to warm-up procedures.
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Indy Dan is using a 4mm longer rod, same compression height piston as stock Polaris, shim and machining base of cylinder. All this for support of piston skirt and cylinder skirt support which is a good idea.
Just needs some fine tuning/machining to get hp back as some is lost with this method . Nothing wrong with what he's doing , but there is ways of doing similar with great hp/tq gains is all I'm saying
 
Brock said:
Indy Dan is using a 4mm longer rod, same compression height piston as stock Polaris, shim and machining base of cylinder. All this for support of piston skirt and cylinder skirt support which is a good idea.
Just needs some fine tuning/machining to get hp back as some is lost with this method . Nothing wrong with what he's doing , but there is ways of doing similar with great hp/tq gains is all I'm saying
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Tore a couple apart to see over the years
 
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I think what's critical George. Is measuring the ring end gap before installing. A lot of people just slap pistons in and that's not the correct way . To small of ring end gap and it will bind .

George A Twitchell said:
Brock, Look at the photo of Gen 2 piston along with PRO/AXYS and the ring closure/pin (pin being in the center of the ring groove) and compare with Weisco when you get them and this is what I am talking about. The Weisco that I will forward along the photos of will show the scuffs and unusual ring wear at the closure area. I think due to this type of ring end, it causes the ring end to flex or deform slightly causing the issue that I seem to be seeing and in my case, going back to Polaris Pistons and for fix-kit (shim plate) Arctic or Sno-X (arctic aftermarket) so far I have seen no issues of the past scuffing. I will be endevoring to measure the offset (or not) of the Arctic pistons as I do not know!? Anyone else know that answer here? Again, asking which way did Polaris offset the piston pin,,, pin to the front (exhaust side) or pin to the rear (intake side)???? I will be measuring this when I get to the mill and can chuck a piston in the mill table vice and get the dial indicator on it.
gtwitch in wyoming
Click to expand...
 
My opinion only here ,but, I think this type of ring end closure, the ring closure is asymertically on the axys of the ring and tends to roll or flex and the two or three sets that i have taken out because of scuffing in line with the closure (both on the piston and cylinder) supports my thoughts/opinions. I had built these Fix Kit engines myself and know that the ring end gap was correct and have since changed to the Polaris/Arctic type of ring closure over the grove centered pin. Years ago when I was building engines for racing , Free air cooled and liquid cooled later, I used a lot of Weisco pistons but then, they had an "L" shaped ring (great design) and a full over the pin closure. and I had great luck with those rings. Again, I am only passing along my most recent observations and results and I am sure that there could be other causes, but my opinion only!!
gtwitch in wyoming
 
Also another cause could be piston taper where the top where the rings are could be enough smaller that this could cause rings to flex at the time of the start of the burn (TDC), Something to consider. Thighter tolerence design as mention earlier in this thread!
gtwitch in wyoming
 
Great points and observations George . I agree with you .


I'm willing to try Kelsey's pistons for the first time. As I said earlier. I mark down all measurements before install and after many miles or worse case scenario, burn down .
I've never tried Kelsey's pistons and have agreed too give it a go.

I see the rings are tapered thick outside to thiner inside like the cats, piston has less taper then the Polaris piston from bottom to top, shorter wrist pin, ring lands spaced different, etc .....

I'm going to make them lighter with titanium wrist pins w/DLC too
 
Brock, Give/send along the contact information for Kelsey so I can contact and/or look at the info and what do these pistons weigh and what does the pin weigh?? I assume these are the same length/height (compression height) as the Polaris piston. I do not yet have the weight of the new AXYS 800 2017/2018 Piston as my dealer has none in stock yet. I might have to take my postage scale and go to another dealer in the Denver area after calling ahead.
gtwitch in wyoming
 
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Rk tech piston all stock is 536 grams
With a titanium wrist pin that's about a 1/4" to long is 512 grams as you can see . Should be around 500 grams with proper length titanium wrist pin
Compression height is the same
 
WOW 82 grams is a bunch!! What about the weight of just pistons as most of us would probably opt out of using the TI pins, although it is a great idea but $$ part might be the factor here. I assume the 584 g piston on the right is the AXYS?
gtwitch in wyoming
 
Pistons were weighed with everything. The piston,rings,wrist pin, wrist pin bearing and clips.

Rk tech wiscoes are 536 grams
Polaris is 584 grams

The titanium wrist pins with DLC are 40% less weight then the steal stock pins plus the DLC resists wear and friction.
 
Ti-17 titanium is stronger then any steal.

To answer your question? Yes it will hold up. I tested them since 2001/02 ice and grass drag seasons. It was hugely expensive back then with dlc coating, wow!!

Anyways. I used a set of stock pins, pins of titanium with a steel outer shell pressed over titanium around 0.125" thick and pure Ti-17 with dlc . The steel had the regular heat (blueing) while the Ti-17 pins with dlc didn't have a mark. All you could see was an outline of were the wrist pin was. DLC coating is amazing .

Used it for trail riding after without any problems for 3200 miles before I sold sled .

Now I'm using it again as it's less expensive as 15+ years ago.

Honda and Ferrari started using Ti-17 with DLC back in the early 90's for connecting rods, valves, and wrist pins. It's stronger then steel and lighter. It's used for way more stuff too.

Check out Ti-17 titanium with dlc for yourself ?
 
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Rk tek piston weight with titanium wrist pin with DLC coating . It's about 80 grams lighter then stock .Div20
 
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