registered user Posted March 16, 2013 Report Share Posted March 16, 2013 if the exh flange is round and the end of the exh port is stepped it should increase the velocity when the exh comes back through the pipe. it was explained to me like if you have a garden hose and put your finger over half of it. what happens well the water squirts out alot faster. i never polish my exh port either. Quote Link to comment Share on other sites More sharing options...
BLOODRAGE Posted March 17, 2013 Author Report Share Posted March 17, 2013 So now it's best not to polish the exhaust port? Shit just never ends Just like how some people polish the intake and some don't Quote Link to comment Share on other sites More sharing options...
Coupelx Posted March 17, 2013 Report Share Posted March 17, 2013 The gain just isnt worth the time. I finish mine with 320grit emery cloth on a slotted mandrel. A few years ago i watched a deal on acceleration enrichment theory (automotive) which talked about cylinder wall and port wall wetting. One thing that was mentioned was port surface texture. The texture is there to keep the fuel in suspension NOT to atomize it as is so commonly repeated on this forum. If the shit isnt atomized when it comes out of the carb you have other problems. Quote Link to comment Share on other sites More sharing options...
registered user Posted March 17, 2013 Report Share Posted March 17, 2013 most people that polish the exh probly do it for the reason they think it reduces carbon buildup. im not convinced though. maybe ask your question on one of the engineering forums but i think a rough surface will transfer heat better. and keep the boundary layer at a minimum ? Quote Link to comment Share on other sites More sharing options...
BLOODRAGE Posted March 17, 2013 Author Report Share Posted March 17, 2013 I've actually seen the carbon build up on a set of polished cylinders.so that is why I'm a lil shocked to hear it doesn't produce much power to even bother polishing the exhaust.but that is why we are here in the first place is to learn and share idea's.damn thing is I just polished one jug on a Athena kit and not so sure about doing the other lol Quote Link to comment Share on other sites More sharing options...
registered user Posted March 17, 2013 Report Share Posted March 17, 2013 Heat transfers best between to polished smooth pieces. Reason for less carbon build of on a rough surface would be air turbelance doesnt allow carbon to reallt come in contact with walls? what does 2 polished pieces have to do with anything ? we are talking about why people polish the exh port. some say it accumulates less carbon. im not convinced though. maybe its a negligable amount less buildup ? carbon collects on the pipe walls and theyre smooth. maybe it has something to do with the wall temperature. i really dont know from what ive seen it takes years for anything to build up in the port anyways, regardless what texture or smoothness is on the wall. by then youll have taken the engine apart several times for a new piston and clean out the port so it dont matter anyways Quote Link to comment Share on other sites More sharing options...
Pasi S. Posted March 17, 2013 Report Share Posted March 17, 2013 I think it´s a good idea to find out how far you can go. LOL! Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted March 17, 2013 Report Share Posted March 17, 2013 I know those aren't done, but please tell me that's not your work! Quote Link to comment Share on other sites More sharing options...
sheerider11 Posted March 17, 2013 Report Share Posted March 17, 2013 I've personally seen very few cylinders with carbon built up in the port. I see it more in the exhaust. Have to be running pretty lean, or just pumping constant heat out to really build up carbon. The unburnt mixture is a nice barrier on the port. We don't have power valves that change flow and direct heat and mixture. It's a constant at all times. Quote Link to comment Share on other sites More sharing options...
Pasi S. Posted March 17, 2013 Report Share Posted March 17, 2013 I know those aren't done, but please tell me that's not your work! That´s the best I can do. We all need to start somewhere. OK, I need some Moroso A+B here and there, but these should make desent power when they are done. Quote Link to comment Share on other sites More sharing options...
Coupelx Posted March 18, 2013 Report Share Posted March 18, 2013 Ive got a cylinder like that along with one i sectioned on a bandsaw. Its all about seeing where the meat is. Quote Link to comment Share on other sites More sharing options...
camatv Posted March 18, 2013 Report Share Posted March 18, 2013 my personal results with polished ports resulted in going to a very rough exhaust. carbon builds up in low heat area's if the exhaust port wont get hot enough to burn the shit off it will collect. i have in years past had to clean many many moped exhaust ports out becahuse they had become so restricted the motor wouldnt even run. just cause its on the net dosent mean its true.. i also cannot rember ever reading any reputable magazine article that suggested polished exhaust ports. to me they are there because it looks good and it seems to me most people buy according to looks instead of performance. the things that recently got me thinking were the changes in 4 stroke swirl patterns and using wet tech to change the way fuel. air enter'd the ports. some of these things i think can be transfer'd into 2 strokes. to me 2 strokes are very very hard to suggest use a flow bench on. the flows are constantly changing and there is no way a flow bench can duplicate what the dome is doing and what the pipe effect has on the cylinder. at least as far as i know. Quote Link to comment Share on other sites More sharing options...
Colby Posted April 1, 2013 Report Share Posted April 1, 2013 80% of people that ride nowdays (not serious racers) will buy for looks over performance even though it costs more. i've never read anything that suggested POLISHED exhaust ports, but Mazdizzy is the one that comes to mind when talking about a SMOOTH exhaust port .. no polished Quote Link to comment Share on other sites More sharing options...
Guest mumshouldaswallowed Posted April 2, 2013 Report Share Posted April 2, 2013 dont let enybody stop you from doing whatever! ive changed pistons on my rm85! painted my car with 2 pac! design and made a rear bar body kit from fibre glass! 1st time playing with fibreglass too! plastic weld, crash pad on cars for airbags ect! built my own computer from scrach! took out and replace fuel pump on diesel forklift! built a shed! change timing belt, crank seals, on my car! engine swap! tattooing! waiting for an gsx wreck bike so i could pop the engine into my yzf450 rolling chassic! just because i can! cus i want! cus i could! ect ect ect ect kinda out of ideas! atm iam getting ready to rip my banshee engine apart in the near future for the 1st time ever! IF THEY CAN DO IT! SO CAN U! enybody want prove me wrong!?! from every corner to every street. money is power! knowledge is power! in my opinion. porting wouldnt be that hard. i have cham. knife edge my rm85. its not that hard. the only thing i would be concern is knowing were to widen or extends the ports. in what place. ect. just my 50c haha. Quote Link to comment Share on other sites More sharing options...
locogato11283 Posted April 2, 2013 Report Share Posted April 2, 2013 Did you say you and 2Pac painted your car? Quote Link to comment Share on other sites More sharing options...
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