tfaith08 Posted May 13, 2014 Author Report Share Posted May 13, 2014 $4.50 for a pack of cigarettes, or a SuperFlow flow bench? I think I know the answer lol. I would absolutely not call this a method of quantifying your port work by any means, but it is cool. Quote Link to comment Share on other sites More sharing options...
camatv Posted May 14, 2014 Report Share Posted May 14, 2014 just a thought.. a larger case will increase overall lower end cc and lower lower end compression. this WILL widen the power band a lot more. that is the reason i would guess for the larger cases. also most of the jet's i have been around were case reed inducted. this leads to a certain power band normally. and most were broadened more with the addition of powervalves.. a larger case can lessen the pipes hit, and the pv will make the top end able to really make rpm and power a multi prop really hard. but still be very controllable to lessen the problems with cavitation.. just a thought. and all that ya hoo on the different transfers doing this and that the pressure drops significantly as the transfers open up. depending on the ratio and the cranking compression in the lower end. your thinking on aiming the boost ports and altering the paths to the transfers with them is what i did in a way.. only a lot different that what you had described in that huge post.. adn looking at different dirt bike cyls and some of the stuff done on 250r's also. i really think you should concentrate on an r motor if thats what you have access to. or at least try and dyno the differences your doing with the blaster motors. my limited time with blasters reveal just simply cleaning everything up and rebuilding the motor and truing the crank up nicely, and a decent tune on the carb made huge difference's in the way they ran. also being an air cooled as they heat up power drops off a lot. some of the things your thinking are happening are described in detail in most of the books i have also read.. you really need to loot for a few differnt 2 stroke tuning books. please just get some and read them already. the angles onthe tops of the transfers also control rpm powerband characaristics but not as much as i think they claim to in the books. most times i run a flat top transfer on a lower end rpm motor (9500 and down) but still have played with mixing them like the banshee oem cyls are done. Quote Link to comment Share on other sites More sharing options...
camatv Posted May 14, 2014 Report Share Posted May 14, 2014 on the r boyesen ports. take the air filter setup off the bike start it up and hold a piece of cardboard close to the carb watch how much fuel spray covers the back of the board.. what do you think happens around the reeds... if you think the fuel/ air flow is only coming through the motor in a constant one way path your not looking at it the right way.. it goes back and forth a lot on 2 smokes. the pipe helps control it a lot more than you think but not all the time Quote Link to comment Share on other sites More sharing options...
camatv Posted May 14, 2014 Report Share Posted May 14, 2014 also the reason i dont think superflows work well with smokers. they cannot ( at least as far as i know) simulate what the pipe is doing and the starting and stoping of flow from the up down from the piston movement... Quote Link to comment Share on other sites More sharing options...
turbowrenchhead Posted May 14, 2014 Report Share Posted May 14, 2014 Good example of why I go elsewhere to try to learn more....someone wants to discuss somthing like 2 stroke theory and operation and nine times out of ten the input is "send it out to a sponsor". When people come hear and want to learn or discuss somthing like port designs or expansion chamber design, then the flaming begins.....There is a difference between guys wanting to discuss to try to learn more, and then guys that come here trying to prove somthing... I hear ya. I posted last year asking questions about DYI porting. Wow what a bunch of rude comments I got. Well I didn't listen and ported my own cylinder. I did the exhuast, intake and added boysens. My job got my 58HP on the dyno. 1 Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted May 14, 2014 Report Share Posted May 14, 2014 I hear ya. I posted last year asking questions about DYI porting. Wow what a bunch of rude comments I got. Well I didn't listen and ported my own cylinder. I did the exhuast, intake and added boysens. My job got my 58HP on the dyno. Ya, only one Negative Nancy so far. 58 sounds pretty decent !! Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted May 14, 2014 Report Share Posted May 14, 2014 on the r boyesen ports. take the air filter setup off the bike start it up and hold a piece of cardboard close to the carb watch how much fuel spray covers the back of the board.. what do you think happens around the reeds... if you think the fuel/ air flow is only coming through the motor in a constant one way path your not looking at it the right way.. it goes back and forth a lot on 2 smokes. the pipe helps control it a lot more than you think but not all the time A piston port engine has a literal fog at the carb mouth. Quote Link to comment Share on other sites More sharing options...
registered user Posted May 14, 2014 Report Share Posted May 14, 2014 it may have been better you didnt get much advice from websites. there must be 100's of 2t sites and alot of the info posted is bullshit that can lead you down the wrong road. books aint a bad way to learn a few things. atleast you know the author most likely has a pretty good back ground in how the engine works. practicing on a few engines aint a bad way to learn either Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted May 14, 2014 Report Share Posted May 14, 2014 Sacrificial research.... Quote Link to comment Share on other sites More sharing options...
tfaith08 Posted May 14, 2014 Author Report Share Posted May 14, 2014 58 isn't bad. Flotek has 60 posted online for his port with Toomeys, V-Forces, 20cc domes, +4 timing, and a filter. I do tend to start a post with a short, straight forward idea and it turns into a 10 paragraph rant about one thing. I'll try it here. On the roof angles, I know that there's a lot of correlation to the aiming (front/rear). A Banshee has a pretty steep angle on the secondary, but the ports are angled back pretty well there. On the 250R, the ports aren't as steep, but they're not angled as far back either. I'd like to angle the transfers back some more on the R, but the ring gaps are right in that area and the owner won't drop the money to get a piston so that I can measure this one. I have a few things left to do with this next COMSOL model and I'll post some pics. Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted May 14, 2014 Report Share Posted May 14, 2014 Wonder what the factories use? Would be cool to see what actually happens(inside cyl)(A/Fm swirl) when on/off the pipe. Would probably take some NASA quality shit. Transducers, infrared, cameras. I would like to see comparitive graphs of w/wo boost ports (no other change). How much they actually add and where. Also what the A/Fm velocities really are. For the mix to make it from the reeds to the cyl @ 9,000 rpm it has to be moving pretty damn fast Quote Link to comment Share on other sites More sharing options...
registered user Posted May 16, 2014 Report Share Posted May 16, 2014 the power loss without a boost port probly wouldnt be as much as you think although it probly depends alot on the cylinder design (it would be real easy to plug the boost port on most any cylinder with epoxy and test this theory and epoxy is easily grinded back out). side transfers pass the majority of the mixture. and since the transfers of most all cylinders meet at the rear portion of the bore, and often times are angled up, the mixture is already heading in the same place the boost port would take it anyways. im not sure of the exact reason but i dont think the engine would run any better if the rear trans were widened completely to the 180* rear. so instead of leaving a dead wall at the rear with nothing you have a boost port that contributes alittle maybe some of the exh gas is supersonic in speed like when the port first opened but im pretty sure everything on the intake side is subsonic. other than that i dont know a exact speed and i doubt if many other people know either Quote Link to comment Share on other sites More sharing options...
tfaith08 Posted May 20, 2014 Author Report Share Posted May 20, 2014 The problem there is that the transfers would have a rapid change in cross area if you widened them up that much. Piston support with the reduced sleeve area would probably cause a few problems, namely with the rings bulging, but I see what you're getting at. Someone mentioned it earlier (or maybe it was another thread), but modern designs use triple transfers on each side. This really does a lot to keep the mixture flowing in the intended path. Again, it was also mentioned that there is a lot to be gained from getting the mixture into the cylinder in a controlled manner. The triple ports do a lot to help that, I believe. There are a lot of things that fall into the "minor gains" territory, and those are the things that intrigue me. It's obvious that aiming a port in the right direction will provide some nice gains, but things like adding a radius to an otherwise straight surface to pull the mixture in the direction of the curve are things that fall into that group. A dyno and a lot of time are needed to create an above average port configuration. The difference of 2-3hp from small things isn't that easy to come by. Sure, you can get that extra few hp from shifting the power peak to the right, but what about those that want a wide powerband? Some of these things are so incremental that an inconstancy on the dyno will cover up that gain. However, 10 or so small changes can add up to an extra hp or better response throughout the RPM range. After some time, you stumble upon well in excess of just 10 little ideas. However, you do have to consider just how difficult it is to create the same configuration over and over, especially on large surfaces and hard to see areas. I'm working on a 250R cylinder that I'm grinding the transfers much further forward on. It gets really hard to see some of those small changes that you did the day before. Therein lies the implication that one must make no more than one change at a time. 9-10 different bikes with the exact same parts will all produce a slightly different power curve. However, the largest drawback is that spending an extra 3-4 hours doing some very detailed work for only another 1-2 hp isn't worth it to most people, especially professional builders. For the DIY with spare time that isn't consumed by anything else, he may benefit from things like this. Quote Link to comment Share on other sites More sharing options...
camatv Posted May 20, 2014 Report Share Posted May 20, 2014 the factory's use testing to come up with what they want. if you want an interesting read on that get gorr's modification book for dirt bikes. in there there is information on mis matching differnt year parts on differnt versions of motors to get differnt power bands some of it is really intersting. also a lot of differnt ways to get more power out of bad combo's and a lot of great info on getting what you want with what you have.. i really think you would find that interesting.. back in my mx days i set up a lil 125 cr just the way the book described and it was ran in the class where the bike year onlymatter'd he usually out ran the 250's and most times was right onthe back tires of the 500's most times the bike finished in the top 3. it was a really rideable bike. Quote Link to comment Share on other sites More sharing options...
tfaith08 Posted June 14, 2014 Author Report Share Posted June 14, 2014 I've tried to get my hands on it a while back, but gave up because I didn't know it was that good. I'll check into it. I'm about to get into a KX85 this weekend. The guy wants it ported, so I'll be doing the math here if I get the time. I haven't been in a cylinder that small in a long time. Time to go get some more 1/8" tipped carbides. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.