I was wondering, what exactly is port and polish mean? the way i took at was that the exhaust was polished to allow for the exhaust to flow out better and porting was to allo more of the air-fuel mixture in? well i took my engine apart and the exhaust was smooth as hell and the port are a little larger then a stock cylinder, well i asked the guy i bought it from what size piston it was because i was going to put new piston and rings in and he just bitched the $hit outta me saying if i even put a different piston in it, all the port and polish work would be shot? now i asked a few other people and they said this guy was full of $hit, but he says he's right. i know theres some smart people in these forums so someone please help me out here. would like to know soon so i can either tell him off[img]i/expressions/face-icon-small-wink.gif[/img], or just put it back together the way it came apart, though i do think it could use a fresh piston and rings. i know that much. thanks for any help. oh! one more thing, i can pick up a reed spacer pretty cheap, they worth the money or not? thanks again

 

please could someone respond to this?

 

You have some good questions, and I hope my knowledge can shed some light on the subject. If I am incorrect in any of my information, I hope someone would politely correct me.

Basically when you are going to port and polish your jug, a SKILLED person would have a template or an idea of exactly what needs to be done. They would then take a type of auger and remove some material from the ports and the exhaust. Then the would take a polisher and make that serface as smooth as possible to promote even flow with low friction.

Now comes in the piston factors. In my experiences I have alway had the jug machined or bored to the specs of the Piston, because of tollerances each piston is different. So I can understand that factor in what the guy told you... I would not just change the piston with out taking a mic to make sure the size of the new piston is in spec for what diameter the bore is. But to answer your question... I dont see how changing the piston will effect the port and polish job unless he put some custom fabrications on the piston as well.

I hope that answered your question...

For a reed spacer, check out Ebay... They have tons of stuff out there. Just search on 250R.

 

Well you might as well forget about telling that dude off,as he sold the encyclopedia's long ago,Of course you can change pistons w/o ruining the port and polish.Maybe he can explain how a piston can effect area's that are not even touched by the piston.You should have the bore measured to see if the same size piston will work (cyl. may be wore),if so the next size up would be needed..good luck [img]i/expressions/face-icon-small-smile.gif[/img]

 

The only thing that I can think is that the piston has been sectioned. The crown has been machined, which as LT80 alludes to would change the time area. But this is very uncommon, and it typically only done for R&D. (Section a $60 piston instead of possibly ruining a $300 cylinder with a radically experimental set-up)

Sounds like somebody wants to feel important and all exclusive. Either that he is trying to hide the fact that it may not have had any work done to it, and you would discover that when you pull the cylinder to replace the piston....

As for the reed spacer...There are different applications and different results. Its relatively in-expensive, and the results are in-line with that as well. Its not a WOW where did that power come from- The reed spacer. The reed spacer may tame down the "hit" onto the pipe some. Of chief benefit for a reed spacer in a 250R cylinder is that the cylinder has auxillary transfers. The reed spacer moves the tips of the reeds back, unmasking the aux transfers allowing for potentially more flow.

My advice. Make some time runs, buy the spacer, install it, make some more runs and compare the results. If you gained time, or prefer the way it runs---by all means run it. If you arent gaining time or changing the personality of the engine to your liking...Hang it on the wall and put it on Ebay.

 

I'm with lt80, just possibly he has a high compression piston in thier as well.
When you port and polish it does a graet job to the performance, but most of the time it takes from the bottom end, so a higher comp piston conters that.
What ever you do, just bring it to a machine shop and have them size it correctly.

 

thanks for all your help guys, the sizing im not worried about, my dad when he was younger raced snowmobiles so he has tools up the **** for measuring jug sizes and piston size, he even told me that the piston has nothing to do with the port and polishing procedure, yeah its a pro X piston but from what ive heard about them, is that its just another piston company with good background. the reason i asked on here is because my dad sometimes blows smoke up my **** [img]i/expressions/face-icon-small-happy.gif[/img] well thanks again for everything.

 

Dad's are cool aren't they? Don't worry to much about that smoke, I think all dads do that to their son's I know my dad sure enjoys it. But occasionally a little roost might go his way[img]i/expressions/face-icon-small-happy.gif[/img] whoops! I didn't say that did I?

Biggerisbetter.

 

gaff,
What you said about a high compression piston may be true in fourstrokes, but not two. In two strokes, you change compression by the cc displacement of the dome, or by milling the head. Not by the piston, Just thought i'd let you know in case you went looking for a high compression piston for a two stroke and couldn't find it.

 

hey hondaman, my head was milled, what if i was to change the head i have to a DR powerhead??? would that mess things up or not? i forgot to mention that.