badbanshee509 Posted October 24, 2012 Report Share Posted October 24, 2012 I know that their is a big bore and a small bore sheaere out frame pipes, but what is the difference in the two besides the size of your motor, will small bore perform on stock cylinder better then big bore will? will big bore fit in a stock cylinder and perform just as well? are shearers out frame better then cpi out frame, i currently have a 411 cc 4mil crank with i thank 64 or 65 mm cylinder bore. i am looking for the best pipe for drag, as you guys can tell i am new to the drag sean, however i am willing to learn and become the best in the 4 mil class hear in florida i want my bike to run like a 10 mill, i have seen it done but no one want to give out the secret. Quote Link to comment Share on other sites More sharing options...
Nightmare Posted October 24, 2012 Report Share Posted October 24, 2012 Big bore pipes are made for 535cc or larger. U cant put big bores on stock cyls, that would be retarded. As for your 411, small bore Shearer or cpi's would be your best bet. There's lot's to learn here. Quote Link to comment Share on other sites More sharing options...
badbanshee509 Posted October 25, 2012 Author Report Share Posted October 25, 2012 (edited) i do plan on going to 68mm bore stock cylinder so should i just stick with my cpi or should i trade some one for some small bore shearer pipes, i hear thet the shearers make extream power for drag bikes Edited October 25, 2012 by badbanshee509 Quote Link to comment Share on other sites More sharing options...
SlowerThanYou Posted October 25, 2012 Report Share Posted October 25, 2012 Most combo's like being described should work the best with small bores. We run Big Bores on a 443 cub and they work excellent for our combo on sand & asphalt. Quote Link to comment Share on other sites More sharing options...
Nightmare Posted October 25, 2012 Report Share Posted October 25, 2012 Try and borrow some shearer and run them back 2 back and see what it does, thats what i did. I have time slips in my gallery to show the difference. Quote Link to comment Share on other sites More sharing options...
badbanshee509 Posted October 25, 2012 Author Report Share Posted October 25, 2012 (edited) also to mention i am running m1 fuel, and also the guy up top "nigntmare"said big bore goes on 535 and bigger Edited October 25, 2012 by badbanshee509 Quote Link to comment Share on other sites More sharing options...
SlowerThanYou Posted October 25, 2012 Report Share Posted October 25, 2012 Big bore pipes are made for 535cc or larger. U cant put big bores on stock cyls, that would be retarded. As for your 411, small bore Shearer or cpi's would be your best bet. There's lot's to learn here. I guess I have a lot to learn, LOL! Quote Link to comment Share on other sites More sharing options...
Nightmare Posted October 25, 2012 Report Share Posted October 25, 2012 Most combo's like being described should work the best with small bores. We run Big Bores on a 443 cub and they work excellent for our combo on sand & asphalt. Hey, if it works for u its all good Quote Link to comment Share on other sites More sharing options...
gotta_goatsfast Posted October 25, 2012 Report Share Posted October 25, 2012 Its a general rule of thumb..... there are-however-exceptions. As for a stock cylinder, I don't think you could move enough volume of air to warrant big bore pipes usefull. Why are you sticking with stock cylinders? If stock cylinders are your top choice, I would not run 68mm bore on them. While you DO increase in displacement (68mm X 58mm) 421 vs. (65mm X 58mm) 385cc... not even close to 411cc by the way... the larger sleeves push into the transfer ports and coolant passages. IMO, you'd probably make more reliable power just having them drag ported by a reputable builder. If fast is your goal, it comes down to WAY more than the size of your motor. The secret to hard running motors is the entire setup. All the engine components must be designed to work with each other. From there, spot on fuel and ignition tuning.... and this is just the engine. The chassis, suspension, tire selection, gear selection, clutch setup, ect must all be selected to compliment the motor's power AND your riding style. Each of those areas can be tuned as well. But the most important piece of advice I have to stress is USE QUALITY PARTS and take your time building everything right.... double checking all tolorances and measurements. The only way to win a race is to make it down the track! Fixing your machine all the time is embarassing, costs you races, gets expensive, is time consuming, and the end result is usually a bad attitude. Good luck with the research and poke around. If you're only interested in stock cylinders for the "stock appearance" try searching the "Wampus" line of aftermarket cylinders from CP industries. It is very similar to cub cylinder specs with the outer appearance of stock cylinders. Quote Link to comment Share on other sites More sharing options...
badbanshee509 Posted October 25, 2012 Author Report Share Posted October 25, 2012 but not every one can go out and but three sets of pipes, i trying to figure out which one will make the most power with my set up 411cc shearers or cpi both small bor pipes? im actually consitering trading my out frame cpi for someoneselses out frame shearers so i want to know that im doing the rite trade for my bike, im asphalt drag. Quote Link to comment Share on other sites More sharing options...
badbanshee509 Posted October 25, 2012 Author Report Share Posted October 25, 2012 but not every one can go out and but three sets of pipes, i trying to figure out which one will make the most power with my set up 411cc shearers or cpi both small bor pipes? im actually consitering trading my out frame cpi for someoneselses out frame shearers so i want to know that im doing the rite trade for my bike, im asphalt drag. so i guessing the benifit would come from using small bore shearer pipes if im not correct please correct me Quote Link to comment Share on other sites More sharing options...
J-Madd Posted October 26, 2012 Report Share Posted October 26, 2012 Degree your motor and see what the exhaust duration is. On drag ported stock cylinders its usually 200+ degrees. If so, CPIs would be your best bet. Quote Link to comment Share on other sites More sharing options...
shanYE west Posted October 26, 2012 Report Share Posted October 26, 2012 Most combo's like being described should work the best with small bores. We run Big Bores on a 443 cub and they work excellent for our combo on sand & asphalt. I agree. I've used BB's on my 421 also. Got BB inframes on a 10 cub also.. runs great!. Quote Link to comment Share on other sites More sharing options...
camatv Posted October 29, 2012 Report Share Posted October 29, 2012 good lord 200+ must be a light ass rider adn chassis set up!!! i have a stock cylinder 421 ( 68mm bore 4 mill stroke crank) its not a "drag bike" by any means but it runs very well. lots of tq on it BUT as stated its a HUGE combonation of correct domes, reeds, correct porting, crank true, piston balance, ignition tweaks, etc etc etc that got it to that point.. my wife's 350cc has spanked a bunch of 4 mills in its limited exsistance. most of that is from massive porting and lots of tuning and motor set up. along with a chassis it dosent overpower and is easy to ride. in my opinion thats one of the biggest things i see screwed up on smaller builds. jsut chassis that cannot handle the hp or cannot put it to the ground.. Quote Link to comment Share on other sites More sharing options...
badbanshee509 Posted October 30, 2012 Author Report Share Posted October 30, 2012 so are you truyng to say the port is the most powerful part of a build, because i have herd from the great vine lol that if it is to big of an port, that too can harm the bike performance as well, im new to this so if im wrong help!!!!!! i am trying to get my foot in the drag racing scene so thats why all the questions. Quote Link to comment Share on other sites More sharing options...
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