I'm set in my beliefs? I have facts to back up my beliefs. The forged piston is harder, thats why its stronger! But you seem to think that a piston scrapes up and down a bore every power stroke. This does not happen. The rings ride on the bore, not the piston. Does the piston occasionally rub the bore? sure, but not enough to cause the kind of wear you are talking about. If what you are saying was true, cylinders would come apart with no hone marks in them from the prior rebuild, and you and I both know this happens very often (hone marks)

 

<< Eric, after running a two stroke like a 250r, which coincidentally revs alot higher than any four stroke around. >>



Says who? first off I thought banshees rev'd higher than 250rs(mine stops making power on the dyno around 11.5k rpm, wheres your R stop?) and second doesnt the yz250f fourstroke redline at some ridiculus number like 13.5k rpm? And if you've ever ridden one you'd know they get up there in a hurry! So where's your logic stand now?

Second, Heat causes things to expand, the only time you have a problem with forged pistons is if you just kick it over and take off racing, that causes cold seizes, which happens when the bore isnt up to operating temperature and hasnt expanded the little bit that it will expand. After you warm it up the forged pistons run great, Ive been running a set of wiseco pro lites in my drag banshee all dune season and no problems, 210psi, +8 timing advance, 2nd gear launches up to 6th gear on the hill then coasting back down before ripping up it again. Id think that would stress them in the heat/cool down aspect more than you just relaxing and cruising around the trails... Once its up to temp they are fine, and the better piston(again, after you warm them up to operating temperature)

 

please dont incinuate that I think the piston scrapes up and down the bore every stroke.

I know that the piston rides on the rings.

all you are saying is that the forged piston is stronger and that it lasts longer.

your right on both accounts.
what you arent understanding is a forged piston wears the rings and bore out quicker than a cast piston, regardless if the piston is stronger and lasts longer.

Like I said alot of people run forged(weisco etc) pistons thinking there gonna get longer life out of the engine.longer life out of the piston YES, not the ring and bores though.

If you dont care about boring the cylinder sooner than a cast piston engine thats great! Go for it!
that particular forged piston WILL last longer (longevity wise) then a cast, thats why you only change your rings....but...what about the wrist pin, wrist pin bearing and circlips?

You only have so long until a particular bore is out of spec,(depending on your riding characteristics) then you have to bore it and then your awesome weisco forged piston that you bought for 130+ is useless, since you cant use it on that particular cylinder.(if you had another cylinder an a smaller bore then you could re use that piston!)

if you want a motor to last change the top end every 20-40 hours on a two stroke.

mp347


<< Eric, after running a two stroke like a 250r, which coincidentally revs alot higher than any four stroke around >>


I should have said &quot;most four strokes&quot;
sorry bout that




<< 2nd gear launches up to 6th gear on the hill then coasting back down before ripping up it again. Id think that would stress them in the heat/cool down aspect more than you just relaxing and cruising around the trails >>



when coasting after a high speed run. first the engine gets even hotter than the actual high speed run, then it contracts THIS IS WHEN the forged piston wears the rings and bore quicker.The cylinder(s) is actually waiting for the piston to contract and wears the bore and rings faster

 

BeeRock69

You have failed to let all these poor souls that you have tried to convince to run a cast piston that cast pistons are more prone to breakage of the skirt and ruining a topend and bottem end because of that.

Fact of the matter is that if Wisecos are broken in properly and warmed up properly that they last along time with no problems.

And also where is the moderator here to take care of the advertising for another forum in his signature.

 

Ok, guess you better let my motor know that its supposed to be wearing out more, last time I had the head off I still saw hone marks on my cyls[img]i/expressions/face-icon-small-smile.gif[/img]

Out of curiousity you say you were told this and wouldnt use forged again, so Im guessing you have no clue and havent ran a forged piston in years. Wisecos were a lot worse years ago, thats when a lot of people went to niks Pro-x and other cast pistons, but lately the wisecos have been much better and virtually no problems with them(again only problems ive heard have been cold sieze due to not warming the engine up). You are insinuating the cylinder is squeezing around and contacting the piston, because if the piston doesnt touch the cyl and the rings are in good shape no wear would occur to the bore to wear it out of spec. Basically your argument holds no water.

 

<< what you arent understanding is a forged piston wears the rings and bore out quicker than a cast piston, regardless if the piston is stronger and lasts longer.

If you dont care about boring the cylinder sooner than a cast piston engine thats great! Go for it!
You only have so long until a particular bore is out of spec,(depending on your riding characteristics) then you have to bore it and then your awesome weisco forged piston that you bought for 130+ is useless, since you cant use it on that particular cylinder.(if you had another cylinder an a smaller bore then you could re use that piston!)
>>



Wow, more factual information that you've seemed to gather from no where.



<< when coasting after a high speed run. first the engine gets even hotter than the actual high speed run, then it contracts THIS IS WHEN the forged piston wears the rings and bore quicker.The cylinder(s) is actually waiting for the piston to contract and wears the bore and rings faster >>




So now the cylinder contracts faster than the piston? How does it do this (being the liner is made of cast iron)?

 

<< also where is the moderator here to take care of the advertising for another forum in his signature. >>



how petty is that? dill has alink, so does retro.





<< You are insinuating the cylinder is squeezing around and contacting the piston, because if the piston doesnt touch the cyl and the rings are in good shape no wear would occur to the bore to wear it out of spec. >>



its not contacting the piston, the forged piston is contracting at a slower rate so the rings wear the bore faster than a cast piston would, since the cast piston contracts faster than a forged piston. less pressure is on the rings

oh rings dont wear ehh?

all of you have said in one way or another without even knowing it that the forged wears the rings and bore quicker.
you cant understand it though.

it has to do with the density of the cast and forged aluminum pistons and the rate in which the forged and cast piston expands and contracts in relativity to the cylinder bore.



<< so Im guessing you have no clue and havent ran a forged piston in years >>



I run cast pistons, niks prox and honda, there both from art


COLD seizes happen with weiscos, broken skirts happen with cast pistons when there not warmed up properly
I wont run forged, and even with my motor, I let the engine warm up every time.


dill




<< So now the cylinder contracts faster than the piston? How does it do this (being the liner is made of cast iron)? >>



no, but the forged piston contracts slower than a cast piston which in esscence makes the rings wear faster


I am trying to find out exact information on cast aluminum and forged aluminum and iron.

the melting rate, and expansion/contraction rate.

 

Rings wear out, we said that, we havent argued that, however the forged piston does not make your cylinder wear out... Not if you do everything the way you are supposed to. The rings are meant to be the first to wear out, so yeah, rering it regularly(I do it once or twice a year, depending on how much I dune) However im still on my OEM bore, almost 2 years old. Ive honed it once, I tore the motor apart right after I broke it in after buying it, hehe, it had about 3-5 hours on it. Had it setup for full race and wiseco prolites with mods done to them slapped in and I can still see cross hatching from the hone on my bore when I take the head off. So where is the extra wear on the cylinder bore you claim?

 

<< how petty is that? dill has alink, so does retro. >>



These links are to personal sites showing our quads, not a message forum.




<< its not contacting the piston, the forged piston is contracting at a slower rate so the rings wear the bore faster than a cast piston would, since the cast piston contracts faster than a forged piston. less pressure is on the rings >>



It's apparent to me that you really have no idea how an engine works. Lets just say for 2 seconds that you are right. So the bore squeezes down on the piston some. This would not wear the rings any faster, as this is why there is something called ring end gap. The ring end gap will squeeze .0000000001 tighter, end of story.



<< no, but the forged piston contracts slower than a cast piston which in esscence makes the rings wear faster >>



I have just proven this wrong, and in essence, you as being ignorant as well.

 

I gotta agree with Dill and Mp347 on this one. I find it funny how beerock makes him out to be some big motor guy when he acctually knows jack. I come to this conclusion after reading some of beerocks post on this board and others.


I would never take advice from a guy who thinks a Mac500r will be a good trail riding bike with a +1 swingarm.

matt