dusty_v141 Posted October 7, 2009 Report Share Posted October 7, 2009 (edited) i know im fixing too ask the question that alot of people dont know, and the ones that do are not talking much lol. im building a asphalt drag bike and i want too do all the work too it myself because im just that way.i was wondering if any of yaw could give me some port timings too start with or any tips at all. i have been reading alot about porting and i think it cool and i want too do it. Yes , i culd send my jugs off too a builder and have them ported but i would not learn anything and i could not truely say i built the motor. it would be like puting a kit togther if i sent them off too get ported. i just want some good numbers too start with and what not too go past and stuff like that. Thanks for all the info. Edited October 7, 2009 by dusty_v141 Quote Link to comment Share on other sites More sharing options...
locogato11283 Posted October 7, 2009 Report Share Posted October 7, 2009 my opinion is that there are builders out there for a reason. i can take a motor apart blindfolded and know just about everything there is to know about banshees, but when it comes to porting i stick to a builder. it can make or break how your bike runs. you sure this is something you wanna tackle yourself? Quote Link to comment Share on other sites More sharing options...
dragbanshee98 Posted October 7, 2009 Report Share Posted October 7, 2009 the best info you will get from a builder is that there are porting templates on ebay lol... they will not be willing to give away the secrets to their porting, that is the only thing that separates them from other builders other than the custom parts they make Quote Link to comment Share on other sites More sharing options...
crustydemon Posted October 7, 2009 Report Share Posted October 7, 2009 Good luck, nobody is going to give you any usable specs ,believe me I have tried. I guess I cant blame them, I wouldnt either, but it really isnt hard to figure out on your own if you really think it through and do your research, you might even get lucky and come across an old timer in your area that really knows his shit to learn from. I personally would rather destroy a few sets of jugs if I really learned from it than have someone else do my work.Knowledge and the proper tools is all you need. Heres a site that may help a little:http://www.dirtrider.net/ericgorr/eg_port1.html Quote Link to comment Share on other sites More sharing options...
racer Posted October 7, 2009 Report Share Posted October 7, 2009 When making your exhaust port wider, it must be no wider than ~65% of the width of your piston. Ring failures lie beyond that ratio. Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted October 7, 2009 Report Share Posted October 7, 2009 When making your exhaust port wider, it must be no wider than ~65% of the width of your piston. Ring failures lie beyond that ratio. Head over to planetsand. They throw around porting specs in a LOT of threads. Just wander around in the 2-stroke forums over there and you will learn a lot. I've got some port specs from a gorr dune port and a FAST drag port I can hook you up with. What kind of porting are you looking for? Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted October 7, 2009 Report Share Posted October 7, 2009 So if your building a drag car then you would weld and regrind your own camshat so you could say you built it your self? Or would you buy one that is already machined. Quote Link to comment Share on other sites More sharing options...
racer Posted October 7, 2009 Report Share Posted October 7, 2009 So if your building a drag car then you would weld and regrind your own camshat so you could say you built it your self? Or would you buy one that is already machined. Psssh, you don't own a cam grinder? Some mechanic you are. Quote Link to comment Share on other sites More sharing options...
dusty_v141 Posted October 7, 2009 Author Report Share Posted October 7, 2009 lol i knew this would be like pulling teeth from a grizely bear lol.its going too be strictly asphault drag bike so i want a full drag port. i could send them off be out say 450 bucks and have some awesome jugs, or i could do them my self spend probaly that much in tools and alot of time porting them but i will have learned alot about portng and how they flow and all that. im not being an a** hole, i know this is sacread information lol. i just want too be able too do it. how do you think all the big guys ggot started? they had people tellng them its extremly hard to do and an art.if they had of just sent theres off too get done they would not know what they do today.the only way too get somewhere in life, you have too do it yourself; nobody is going too take you there just help you sometimes and im just asking for some help guys. Quote Link to comment Share on other sites More sharing options...
racer Posted October 7, 2009 Report Share Posted October 7, 2009 i could send them off be out say 450 bucks and have some awesome jugs, or i could do them my self spend probaly that much in tools and alot of time porting them but i will have learned alot about portng and how they flow and all that. That is excellent. . . right up until you make your intake divider a little too thin and it relieves itself into your cylinder head. If you're gonna do it take it slow, slow, slow. Quote Link to comment Share on other sites More sharing options...
dusty_v141 Posted October 7, 2009 Author Report Share Posted October 7, 2009 lol ya im going too be really careful and slow lol its going too take me all winter probally till im happy with them lol Quote Link to comment Share on other sites More sharing options...
racer Posted October 7, 2009 Report Share Posted October 7, 2009 What are your plans for cleaning up the cylinders every time you adjust the timing? Flex hone + drill press? Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted October 7, 2009 Report Share Posted October 7, 2009 Asphalt dragger I would go with a 4mill cub cylinder. You would be money and speed ahead. Stock cylinders can only go so far. In order to get a stock cylinder to run with a cub you really need to know what your doing. Drop a cub cylinder on your cases with some decent carbs and a set of drag pipes and be at 90 plus hp. Quote Link to comment Share on other sites More sharing options...
trex banshee Posted October 7, 2009 Report Share Posted October 7, 2009 ok first of all, numbers arent everything. I will tell you many numbers that you can cut the intake and exhaust durations to, but honestly thats half the battle. 65% of the bore on exhaust width is a good safe number, but still they can go more. Depending on the shape, again numbers arent everything! Trust me, ive been porting for almost 5 years now, still doesnt even amount to the dirt under your nails compared to a "builder" but ive done many sets and seen many outcomes. Ill tell you some numbers to start with but thats all they really are; compression, pipes, timing, carbs,rider weight, and lenght of track are just a few things that all play a role. ooohhhh and maybe the ummmm.....shapes and angles of the ports might have a role in this Im not saying this will work best for what your setup is your riding style but they are numbers, thats all you asked for; but remember they are just numbers 199/127 stick with the 65% of the bore for exhaust width to be safe. the rest is up to you, also dont forget that higher durations doesnt always work best for every application..it is your decision to cut the cylinder, i just provided a couple simple numbers i hold no responsibility here. GOOD LUCK. Quote Link to comment Share on other sites More sharing options...
dusty_v141 Posted October 8, 2009 Author Report Share Posted October 8, 2009 thanks for the numbers. i have read about the port width perentage already. im going with some out of frame drag pipes and probally 35 too 39mm carbs and im runing 1/8th mile mostly. im going too start out on gas but will change oo alcahol later. im going too run high compression and i weigh 145 lbs. thanks for the help Quote Link to comment Share on other sites More sharing options...
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