Piston Window ?

thestuz · Post by **thestuz** » December 31st, 2009, 10:59 pm

http://cgi.ebay.com.au/Prox-Piston-Kit- ... 5637a0dd84

100hp honda · Post by **100hp honda** » December 31st, 2009, 11:28 pm

stuz i like your effort but those ebay photos are generic and for illistration purposes only, alot of the time they dont reflect the actual product. thats probly a rm125 piston

thestuz · Post by **thestuz** » December 31st, 2009, 11:37 pm

100hp honda wrote:stuz i like your effort but those ebay photos are generic and for illistration purposes only, alot of the time they dont reflect the actual product. thats probly a rm125 piston

yeah i know. was just showing an example

powermizer · Post by **powermizer** » January 1st, 2010, 1:14 pm

100hp honda wrote:what you trying to achieve is my question ? that kx piston may have gave you some false hope, while it clearly seems it works good on the kawi, that dude probly spent weeks or months to find the perfect size and location for that hole. heres a few things to consider, the intake side of the cr500 piston is a known crack location if the clearance gets too much, cutting a hole only adds to the problem. another thing is i think the new wiseco has thinner skirt than the old version. its a cool idea but you might want to do alot of research before jumping into it.

Can anyone give me advice on putting a window in my weisco piston on intake side. What are the benifits and downfalls to this. I heard it helps keep the crown cool and bearing gets better lube. Any thoughts on power, loss or gains ?. Please help, Thank

pretty much it, Thanks

thestuz · Post by **thestuz** » January 1st, 2010, 2:51 pm

well i just went out and checked a forged (new gen)wiseco, and a cast prox.
the prox has cast lines that will need to remain for strength, interestingly on the heavier but smaller wiseco, there and no reenforcing on the piston so you could make the whole amy where.

the main difference with the kx and the cr piston is the cr has a very small intake side. aprox 40mm bottom of piston arc to bommom of ring structure. now this would only let you cut a whole 10mm long wise but you would be able to make it 20mm wide on the cast and the wiseco.

not sure this mod will work because the cr already has a circumfrence cut out of the lower end of the skirt, where as the kx has the larger/longer piston thet would benefit more with a breathing mod like that. give it a go on a old piston maybe?

http://i48.tinypic.com/snf40g.jpg

powermizer · Post by **powermizer** » January 1st, 2010, 3:02 pm

When I do the cr5 porting I will just remove the whole skirt on the intake side rihgt up to the ring land. Just think of the flow and how light the piston will be, then I wont have to worry about the akirt getting stress from a hole because there wont be a skirt I will need a 90mm carb, anyone have one. LOL

dannygraves · Post by **dannygraves** » January 1st, 2010, 9:41 pm

powermizer wrote:http://quadracerhq.com/DrQ%20RXd%20500%20Piston.jpg here is a piston that Q has done, but it looks like it might be a stroker piston. Gives an idea to what I might need to do.

my gen-1 piston looks like this

iggys-amsoil · Post by **iggys-amsoil** » January 1st, 2010, 10:09 pm

dannygraves wrote:
powermizer wrote:http://quadracerhq.com/DrQ%20RXd%20500%20Piston.jpg here is a piston that Q has done, but it looks like it might be a stroker piston. Gives an idea to what I might need to do.
my gen-1 piston looks like this

Ok Danny ya got me, I want one.

Hey isn't the lower skirt shaped differently? More squared off? Looks like it.

dannygraves · Post by **dannygraves** » January 1st, 2010, 11:34 pm

I was talking about the window. I drilled two 1/2" holes about an inch abart, then cut along the top and bottom between the holes to make a similar looking window.

asteroid500 · Post by **asteroid500** » January 2nd, 2010, 10:45 pm

Danny what were the gains?

100hp honda · Post by **100hp honda** » January 3rd, 2010, 12:14 am

nice danny now everyone wants to do it

powermizer · Post by **powermizer** » January 3rd, 2010, 9:24 am

I like putting holes in the top of my pistons !!!!

fastkart · Post by **fastkart** » January 3rd, 2010, 9:39 am

powermizer wrote:I like putting holes in the top of my pistons !!!!

Makes a 500 kick over like a 125!

dannygraves · Post by **dannygraves** » January 3rd, 2010, 10:55 am

seemed to have been an improvement all over, not really rpm dependent. I noticed a very little bit more right off idle and a bit more into the higher rpms. to me the idea, more than flow, is keeping the reeds open and air/fuel coming in longer. I expected to lose a little down low since the downward stroke wouldn't push as much mix through the transfers, but the positive effects seemed to have counteracted the negative. Of coarse this was a very built motor that didn't make much down low anyway. it is hard to say what the effects would be on a stock motor.

iggys-amsoil · Post by **iggys-amsoil** » January 3rd, 2010, 12:04 pm

Were is the pic / piston that Glen did for Brit?

fastkart · Post by **fastkart** » January 3rd, 2010, 12:12 pm

powermizer · Post by **powermizer** » January 3rd, 2010, 4:00 pm

stupid ?, does anyone hav a picture of stock piston on intake side. Does the piston have a raised skirt ?

fastkart · Post by **fastkart** » January 3rd, 2010, 4:32 pm

Aside from the holes drilled in the piston, that one is same as stock with regards to the skirt.

asteroid500 · Post by **asteroid500** » January 3rd, 2010, 7:08 pm

I dont know about you,
But i'd never drill holes in a piston like a join the dot picture.
If i was a stress crack looking for a holiday i know were i'd go.

23champ · Post by **23champ** » January 3rd, 2010, 7:30 pm

[quote="fastkart"]

quote]

After observing this picture for a while.... It seems like the wiseco pro lite pistons would give the incoming intake charge fits.

While the piston, on its down stroke, is pushing the fresh charge into the cylinder, wouldnt the machined pockets around the piston pin allow some of the charge to be wasted before the piston actually opens the ports?

Also, wouldnt this cause some serious turbulance in the trasfers in the meantime? letting the charge into the sides of the piston(where its machined out), then stopping the charge while the "ringed area of the piston" seals the transfers off again, and then opening the ports back up one more time when top of the piston slides down to open them?

Does anyone understand that? Kinda hard to explain.

fastkart · Post by **fastkart** » January 3rd, 2010, 7:51 pm

I understand. But, it doesn't have to be worried about anymore... Wiseco stopped machining the sides of their pistons a couple years ago.

MICK · Post by **MICK** » January 4th, 2010, 6:16 am

23champ wrote:It seems like the wiseco pro lite pistons would give the incoming intake charge fits.

While the piston, on its down stroke, is pushing the fresh charge into the cylinder, wouldnt the machined pockets around the piston pin allow some of the charge to be wasted before the piston actually opens the ports?

Also, wouldnt this cause some serious turbulance in the trasfers in the meantime? letting the charge into the sides of the piston(where its machined out), then stopping the charge while the "ringed area of the piston" seals the transfers off again, and then opening the ports back up one more time when top of the piston slides down to open them?

Does anyone understand that? Kinda hard to explain.

That's exactly what's happening. When Wiseco began selling us boat anchors, it wasn't just for the CR500, the KX500 crowd noticed this as well. The engine building powers among the KX5 community collectively gathered dyno numbers comparing the old and new gen Wiseco pistons. There was no arguing, the new Wiseco piston makes more power. It's the highest producing horsepower piston any of them have seen.

But off in our own little world we flame and chastise Wiseco for their work and have no measurable proof one way or the other as to the outcome of this new design. We disregard it as being too "heavy".

Ignorance is bliss they say...

I wasn't going to say anything but since the champ brought it up

asteroid500 wrote:I dont know about you,
But i'd never drill holes in a piston like a join the dot picture.
If i was a stress crack looking for a holiday i know were i'd go.

Me neither, but brit says it's saved his bacon on more than one occasion (shrug).

asteroid500 · Post by **asteroid500** » January 4th, 2010, 6:30 pm

Go figure.
(sorry Aussies-i used an Americanisum)
But most of them here are. (not a bad thing)

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » January 4th, 2010, 7:07 pm

the only reason for the side windows in any of the pistons is to cool and lube the pin, thats why in the pin hole is also a notch, lube!
cutting this window in the side without other mods creates an inversion to the reed, not that they arent already closed but it can puddle fuel on the reed

the old TEAM HRC piston is alot different than the shelf items too, wider, taller opening at the base of the piston and they actually pumped 500cc instead of 491 and were lighter, with a wide exhaust face and a narrow intake face that actually had a relief below and ahead of the pin that helped shove wind at the front transfers

but they were used on titanium crankshafts

so i'm told

we can keep buying this jobber stuff thats made because we buy it, they'll improve it once in a while, but it isnt what was out there winning championships, u think Petty ran Hemi engines off the lot too? They didnt even give us the 4 speed trans, or factory decompressor like that Gobers bike ran in '89

blownbillybob · Post by **blownbillybob** » January 5th, 2010, 12:26 pm

23champ wrote:
fastkart wrote:
quote]

After observing this picture for a while.... It seems like the wiseco pro lite pistons would give the incoming intake charge fits.

While the piston, on its down stroke, is pushing the fresh charge into the cylinder, wouldnt the machined pockets around the piston pin allow some of the charge to be wasted before the piston actually opens the ports?

Also, wouldnt this cause some serious turbulance in the trasfers in the meantime? letting the charge into the sides of the piston(where its machined out), then stopping the charge while the "ringed area of the piston" seals the transfers off again, and then opening the ports back up one more time when top of the piston slides down to open them?

Does anyone understand that? Kinda hard to explain.
everything under the 2nd ring is under the same pressure so the side slots should not do much to the transfers. the charge is not wasted until the piston starts to open the int. windows and dumps into the chamber. you have more turbulance in the transfers when the piston starts to travel back up the cyl. it starts to suck part of the int. charge back down them until the piston closes off the window and starts the int. cycle

BannedCR500Riders.com

Piston Window ?