BannedCR500Riders.com

Forgive me if this has been covered but I have not seen it.

I've seen homemade windows cut into the intake side of the piston on forged pistons, mostly wisecos. I'm running a vertex and want to do this as well. Is the cast piston strong enough? Will it crack prematurely?

Any tips on doing it? Dimensions and location? I was going to drill 2 or 3 holes and connect them with a carbide burr and then radius the edges.

How does it effect the power delivery?

I thought the it was more about cooling the piston, but could be way off base on that one.

While you have the piston out try gas porting for better ring seal. I know that's been done with successes on the vertex.

ask roosty....

Gas porting?

Gas Porting:

http://www.wiseco.com/FAQs.aspx

14. What are gas ports and when should they be used?
A.

Vertical gas ports are primarily used in drag race applications. Lateral gas ports are more often used in circle-track and road-race applications where carbon build up can occur. When gas ports are used, pressure is directed to build up behind the compression ring and seal it against the cylinder wall. This helps prevent ring flutter and extends the power curve upward in the RPM range. Vertical gas ports have the holes drilled from the deck of the piston into the top ring groove and behind the ring. Lateral gas ports are drilled through the bottom side of the top land and extend to the back wall of the ring groove.

waiting for someone in the know to respond to this one.

I asked my 2 stroke tuner, he said the window on the intake side is for motors with small intake ports, and that the 500 ports are huge and window is not needed. Doubt it would hurt. you would shave weight.

Wonder what clyde, or adam's opinions are on this one.

If you going to cut a window this big, you better stick to a forging....

Thus my line of questioning. I'm a bit nervous about hacking up a good vertex.

I wouldn't on a cast piece... fragging a piston makes for a really bad day.

i've run the piston port on the OEM pistons before, and cut the window taller. I didnt get much time on that piston, 20 hours maybee, until it got leaned out on the road.

Its more of a mod for guys who'll hold the motor at an rpm more than 5000 for a long time. It will add a bit of low end, its smooths out and increases the delivery up top tho.

I wouldn't run it in the bush like 2stroke forever rides, I would'nt run it for an indoor mx bike. motard, dunes, street, desert, long open mx outdoor i'd be all over it.

I run it on my wossner in my bike, I ride it in tight trails and everywhere else, but I can tell where its better and where its hurting me. I'm also running big exhaust duration and other work in this motor tho.

it takes more main jet, atleast 2 sizes, if you were 178 before, 182 is where i'd start. The needle needs to be richer also, maybee a clip position depending on what it was like before.

I know of some members with similar style ports in their motors, Gss did a round hole and i've seen others do the same style thing with 2 holes. I got talked into it by DeWayne Jones, It was his trick really so I wasn't going to post it up. DeWayne sent me an old piston he did for the Honda team with the work done to it so we could reverse engineer it. Since then I've made it bigger or smaller depending on the piston structure and I don't do the full mods he did at the window because i believe it causes too much reversion onto the reed.

yup, DeWayne was the one who told me to put in a window and what size and where. I noticed that I got a lot more bottomend out of my motor after that but combined with my mikuni carb, it just contributed to the jetting nightmare. I actually liked the performance of the motor better without the window, but with really hogged out boost ports and a far widened exhaust port. When I added the window it brought the peak RPM back down a lot and made the bike harder to control at launch, but no faster up the hill. I then added a lot of duration to the exhaust and they brought it back up and made the bike flat out scarry. No one wanted to ride it anymore when they saw me nearly loop it out everytime clicking into 4th up come hill at dumont

its a wierd delivery for sure, I was on the ice sunday and with actual traction it got even harder to ride it. It'd take off like a tractor, I'd barely get moving then run it in 4th, easing out of the clutch, roll into a wheelie in the first 1/4 of the throttle, then it'd come into a spazy power 1/2 way into it while trying to yo-yo the tire somewhere between the 2ft wheelie and going over backwards, climbing further up on the tank i could get it set down and carry just at the top of the fork travel then it'd accelerate and blow the tire loose

It was such a comedy to try and ride it that my buddy Nick that had his gen4 conversion out there too was busting a nut laughing at me. So we switched bikes for a while. He had different picks that didnt hook up, and was geared 14/51 where i was 14/48 with a 2" taller 120 maxxis. I'd had trouble setting the bike up in the corners to get it kicked out, he got right into it but also had trouble keeping the front tire down. About his 3rd lap of the 1/2 mile loop we were making he comes past our group wfo in 5th, then she squeaks 1/2 a lap later
We did have about 3 hours on the lake by this time and some of the ice fishing guys might have been getting pissed anyways with nick doing 70mph drifting fly-by's 5 feet from their door

I knew i might be a little lean on the jet before i left the house
So i've got it in the back of my truck with these weapon sharp tires and no plywood for the garage floor to unload it on yet. Maybee tonite. It was 0c on sunday, the high for today is -23c

I screwed up with this p.o.s. Contour camera and missed more than 1/2 the days riding. I was so pissed i didnt even watch all of what i did get but i'll post up some pics or a vid from my phone.

Roostius_Maximus wrote: It will add a bit of low end, its smooths out and increases the delivery up top tho.

I run it on my wossner in my bike, I ride it in tight trails and everywhere else, but I can tell where its better and where its hurting me. I'm also running big exhaust duration and other work in this motor tho.

Your first statement sounds like it's a win win, your second statement sounds like it hurts performance????

I'm a bit confused by this "hurt" part. What are the negatives if the hole is set up so the reeds do not flutter?

seanmx57 wrote:

Roostius_Maximus wrote: It will add a bit of low end, its smooths out and increases the delivery up top tho.

I run it on my wossner in my bike, I ride it in tight trails and everywhere else, but I can tell where its better and where its hurting me. I'm also running big exhaust duration and other work in this motor tho.

Your first statement sounds like it's a win win, your second statement sounds like it hurts performance????

I'm a bit confused by this "hurt" part. What are the negatives if the hole is set up so the reeds do not flutter?

the motor isnt as crisp a low low rpm, probably below where most guys ride them, but picks up everywhere else.
Witht he other porting ive done its likely still stronger than stock, but over my other bike that bro took i notice it weaker here.

here is where its hurting
[youtube]http://www.youtube.com/watch?v=Aac4wcEB ... AAAAAAACAA[/youtube]

Not sure if it's the camera, but it sounds like a mix between a boat and a 4-stroke

contour camera, my bikes do sound different

Roostius_Maximus wrote: my bikes do sound different

Flippin' Canadian gas.....

ya, i'm mixing it with baby seal oil too

Freshly clubbed I hope! Lol

I love clubbing.
I love the sound of that thing ..... fkc Canadian post.

The bikes I've ridden with that sounded like that at that pace blew steam a half mile in. But they weren't able to lug even that good.

Never had to add water yet

Now I need a video of you lugging the bike a bit and then winding it out. My bikes only made that kind of sound just before I pop-started them.

[youtube]http://www.youtube.com/watch?v=WgwEtSOP ... e=youtu.be[/youtube]
the contour perspective, its a hillside but the cameras really flatten it out.

here is bro behind me with the gopro, you can tell he's always a little harder on the clutch

[youtube]http://www.youtube.com/watch?v=cC47BFkV ... e=youtu.be[/youtube]

+1 on the gopro sound.

+2 on the wheelie