Atomic Monkey Posted January 31, 2014 Author Report Share Posted January 31, 2014 You're porting it AFTER boring it? I wouldn't recommend that for a new guy. Or maybe you've done several. .i didn't read the thread. Sent from a van down by the river Don't have much choice, going to a different style piston and don't know how it will degree out until the new pistons are in. I did what I could before sending them out, and will just have to lay off the caffine a little when it comes to finishing them. Quote Link to comment Share on other sites More sharing options...
Young Guns Racing Posted January 31, 2014 Report Share Posted January 31, 2014 Just take it veeerrrry slow. At this point a mistake could cost you to rebore and buy new pistons again. Quote Link to comment Share on other sites More sharing options...
camatv Posted February 1, 2014 Report Share Posted February 1, 2014 your boost, boyesen ports are way to small.. all oem cylinders that use boost ports the holes are about the size of your thumb.. also all that stuff you talked about with the intake charge.. look at the reed tip area. thats where your air, fuel flow enters the engine. and rember in this type of setup the "charge" has to almost completely stop, then turn 90* and enter the transfer tunnels.. this effect is something i addressed in my welded cylinders.. to me the only way around it was reworking the intake area completely and welding a bunch of stuff out in the trans tunnels.. also if you read anything you would hopefully of found out that the charge will follow any surface you cut into it. if its rounded the air charge will turn down and across that area, if its straight edged it will cause a major turbulent swirl, ( not such a bad thing).. also if you didnt know the pipes have a major effect on how the transfers, intake work also. something to think about. dump the reed spacers. the boost bottle ehh you MIGHT see a minor minimum tiny effect on a dyno IF you were building for tq only. but to me not worth the chance of a busted intake and all that room it takes up in there. on transfers check this out... of course these vids are without the pipe effect i'm sure.. if you watch them you will see what i mean. i think they are neat. others may not Quote Link to comment Share on other sites More sharing options...
registered user Posted February 1, 2014 Report Share Posted February 1, 2014 i was thinking the same thing on the boyesen ports. with them that small they probly arent making much difference either way. if the casting was thick enough to make them quit a bit larger im still not sure they would make much difference because the main intake appears it can be made rather large. and the piston windows are your boyesen ports so to speak. some engines dont use piston windows and there for rely more on large boyesen ports Quote Link to comment Share on other sites More sharing options...
camatv Posted February 1, 2014 Report Share Posted February 1, 2014 ta da... Quote Link to comment Share on other sites More sharing options...
registered user Posted February 2, 2014 Report Share Posted February 2, 2014 camatv tell us your secrets what you do. make the piston windows bigger ? Quote Link to comment Share on other sites More sharing options...
Atomic Monkey Posted February 4, 2014 Author Report Share Posted February 4, 2014 Thanks again for the great advice! It's one thing to try to visualize what's happening, and quite another to actually see it. I already was planning to skip the reed spacers, and would never use one of the "can" style boost bottles that push into both sides of the intake. I understand boost bottles (on individual cylinders) in their use to buffer the intake pulse through the carb, and the way Yamaha uses the tube between the intakes. I see the point about the Boyesen ports, I wasn't too sure about putting them in, but figured it wouldnt hurt any to try it. Turbulant swirl... there's the concept that's been on my mind as I've been trying to figure out how the transfer tunnels will be shaped to introduce the flow into the chamber. Quote Link to comment Share on other sites More sharing options...
registered user Posted February 5, 2014 Report Share Posted February 5, 2014 i wouldnt be concearned with the boyesen ports. i dont see why they would hurt anything not sure what you can do with the tunells. to be honest theyre not the best shape to begin with. large radius from entry to exit would be better but i dont think thats possible and thats one of the problems with inline twins that have the jugs close together. maybe with epoxy or weld you can do something ? most people dont like the engine full of epoxy so i would just do the best you can and thats all you can do Quote Link to comment Share on other sites More sharing options...
camatv Posted February 7, 2014 Report Share Posted February 7, 2014 i never really noticed a big diffeence in the boost ports untill i welded up the cylinder and made them about the size of most dirtbikes, 250r's etc. i'm not going to just flat out say what i think i figured out. but the boost ports and intake size have something to do with it. its a concept i came up with after staring at the cylinder and watching those animations for a long time. the 350 i did seems to have a very strong lower end pull and more broad range of power after doing what i did. here is a hint rember the oem setup makes the charge make a total stop, and then turn 90* and thanks skeeter for pointing that out. according to every single 2 stroke book i have ever read , re working the stock reeds can make a difference. if you look at them right at the edges there is an overhang that impeads the flow just a tad i think its enough to point the charge more towards the inside of the reeds. taking the edge off ( according to 3 different books written by college professors, 2 stroke software engineers, and based off of lab results posted in these books) it helps straighten out the flow and can also help move more of it into the outside edges of the intake. of course these books were written back when there wasnt a high dollar replacement reed cage with smooth edges available to the general public. Quote Link to comment Share on other sites More sharing options...
Atomic Monkey Posted February 7, 2014 Author Report Share Posted February 7, 2014 I got this quad about a year ago, and have been surprised by what's all been done to it. It came with reed spacers that weren't installed. When it was apart to replace all the linkages after a clutch ball weld, I decided to try the spacers out and put them between the cages and cyls. The cages were "ported" already with two stage reeds, and the cylinders were untouched. What the spacers did was lower and smooth out the hit when the pipes came on, and they also seemed to help gain more over-rev. I'm still staring at these cylinders, and putting together a plan. After watching the videos, I have a fairly good idea how I want to direct the flow. Just still don't know how I want to introduce it into the cylinder... roll it over an edge for some turbulance, or keep a radius for a smoother more direct flow. Quote Link to comment Share on other sites More sharing options...
Colby Posted February 7, 2014 Report Share Posted February 7, 2014 better fuel atomization if the intake is a bit rough .. but will slow down the velocity Quote Link to comment Share on other sites More sharing options...
Atomic Monkey Posted February 7, 2014 Author Report Share Posted February 7, 2014 I've been thinking about polishing certain spots in the tunnels as well, mostly just around the areas where the charge makes its turn into the cylinders. Otherwise when I'm finally finished with with the porting, the intake and transfers are getting bead blasted, and the exhaust is getting polished Quote Link to comment Share on other sites More sharing options...
sprinklerman Posted February 8, 2014 Report Share Posted February 8, 2014 Leave everything rough except the exhaust. Do dome reading on boundary layers and flow. Sent from a van down by the river 1 Quote Link to comment Share on other sites More sharing options...
registered user Posted February 13, 2014 Report Share Posted February 13, 2014 why not make the bridge more like cpi jugs . not that im a expert in aerodynamics or anything. i just never liked the knife edged V shape stuff Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted February 13, 2014 Report Share Posted February 13, 2014 I agree with that^ I happened to get a peek in side some very well performing stock cylinder drag bike. The intake side was a very organic looking design. Turbulence creates velocity if done with a lot of thought. Quote Link to comment Share on other sites More sharing options...
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