What is best to rough up surface???

[Jman271]

In regards to porting, which medium is best for "roughing" the ports w/? I'm thinking cartridge rolls, or maybe even some sort of emery paper w/ mandrel or something? Anyone, Bueller,,,,?

 

[mike perry]

80 grit cartridge roll will work fine.

 

[Jman271]

Thanks guys, that's what I figured. As far as the quote "surface is irrelevant to flow or atomization", I would think that as far as the exhuast side goes, and maybe even the head is concerned, a smoother,(polished) finish in theory would resist carbon build up, and improve the flow, no? I know you guys were mostly talking about intake/transfer, but wdyt about that? I guess most tuners around the New England, (besides Fas Was, he is real good), think that a polish on everything is the way to go. I have yet to see a port job around here w/o everything gleaming w/a high shine to it. I don't want to start a fight w/ these guys on race day and say hey why do you do that, then rebut what they have to say etc,,, but the pits are filled w/ motorwork vendors w/ all their jugs lined up on a tables all shiny and stuff. BTW, thank you for your input on this- :aj:

 

[Shawn Mc]

I got my cylinder back from Allen at CT racing and it was anything but polished. My CR500 runs like a raped ape too. It had all these little chipy lookin markes in the port. Im wondering if he's going for the "golfball" effect. What ever he did, it works really good.

 

[DEANSFASTWAY]

Jman your so right . It seems as though some polishers just polish everything and leave it at that . Most 16 year old kids are impressed by that gleaming shining intake floor and transfers and thats what they like to spend their money on .When I do cyls I dont have the time to spend on cosmetics, but thats what is so impressive on woodsie bikes transfers I like to run the grinder in lines to try to swirl the mix in an attempt to keep everything in orbit and atomized , but I usually do clean up the exhaust ports . Most important with porting is correct timing and pointing of ports . I saw a TRX 250 R cylinder by a guy who had a real good reputation in central PA and everything was gleaming like it was a car rim but when you looked at the area where the sleeve sticks into the intake and case ports on the sides the sleeve wasnt even matched or blended and it looked like all the port heights and shapes were stock . And the price when it hit the customer at the ATV used parts store was like 450 or so . What a joke , but I bet that kid who put it on his quad racer thought it was the meanest thing there was . I am in a quandary as to the justification of some of the pricing for mototrsp[orts performance work . Ethics? I bet GORR feels the same way because I have seen and been a witness to his pricing ideaology he is ethical and his prices are down to earth. But why is it that that same kid would rather spend twice as much ? Does he think its of higher quality because of his larger investment?, Maybe So Maybe its the trickest stickers?. I guess in the short run its the guy with the biggest hype/smoke&mirrors that gets the cheese . But its the guy that does quality and good work at a fair price that stays in business and can go to the track and not have to hide from anybody . CHEERS DEAN

 

[EricGorr]

I asked Professor Gordon Blair about the polishing issue once, wondering if anyone had ever published a research paper on the subject. He said that the most import thing is that the surface finish should be the same on each bank of corresponding transfer ports, along with the same dimensions of course.

The fact is there is so much turbulence in the crankcase of a two-stroke engine, what with the piston going up and down 150 times per second, I don't think surface finis is an issue.

Wes and I have talked about it, we both feel that shiney makes people happy. Hardly anybody measures the port heights before and after porting so all of our mathematical planning usually goes un-noticed. I personally don't waste much time polishing cylinders because I've got too much work and polishing takes too long and you have to charge extra for it, and people whine about prices all the time, comparing prices for hop-ups on motorcycles to the cost of maintenance for their automobiles.

Regarding the "rough look" that is making a resurgence in SoCal hop up shops, that is performed by a tool used in body and fender repair and it serves to change the texture of the intake and transfers in an incredible short period of time. I think that tool is used to increase porting profit rather than yield any performance benefit.

Every once in a while I getted ragged on because I don't mirror-polish the exhaust port. People claim that an engine doesn't make as much power because the gasses don't get out as quick. I tell them that considering the heat and pressure that the gas flowing out the exhaust port is under, a couple microns of difference in surface finish isn't going to hold that gas back and slow the engine down. But its hard to get through to knuckleheads :scream:

 

[SFO]

The valve manufacturer I used to be employed by made only black-nitrited ss valves.
The finish color was black.
When we asked our largest distributor what he wanted from our product line that we didn't have, he said chrome valves.
The nitrite finish was more durable, corrosion resisant and gall proof than chrome but customers needed to see shiny parts when you crank them for 3k for a tricked out drag head.
All the new japanese valves are chrome.
Because thats what people wanted.
Yikes :whiner: :( :think:

 

[korky37]

One of the best cylinders I have ever had was bead blasted on all the intake and transfer ports.Exhaust was cleaned up but not polished like a mirror.The head was a different story , It was like a mirror!The look of the transfer ports was super trick and felt like sand paper.It might not do anything for the performance but I thought it was a clever idea.