sheerox Posted February 9, 2014 Report Share Posted February 9, 2014 So what's the difference between a duneable port job and a MX port job? I'm guessing one is for more low to mid range and one is for more mid to top? And, while we're on the subject, could someone explain the other types of port jobs like drag and trail? Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted February 9, 2014 Report Share Posted February 9, 2014 Your correct on your assumption. Lots of MX motors are 55-65 ish. Most dune porting tends to make motors in the 70-85 hp. Granted these numbers are if the rest of the set up package is there. An MX motor should have a pretty linear curve from bottom through mid and taper off a bit abrupt through 8500-9,000 in my opinion. Maybe with the right tweaks it could fall off less abrupt and more gradual. A dune motor should be pretty strong from the transition off the bottom end through to the top end with a minimal fall off feeling at the top. Albeit many dune motors now a days with 4mil cranks and porting, compression, and timing are pulling stumps from way down low and charge hard well past 9,000. It really is pretty crazy what guys are getting these things to do compared to 20 years ago. As for your question about an trail/ MX port vs. Drag port. The MX port will be more suited to coming on and delivering power from what feels like idle through half throttle with somewhat less pull through the rest. The power is much broader and feels much more snappy. Compared to a typical drag set up, they are more suited to half to full wide open throttle. If you were to ride a. Good drag set up you can feel the throttle response is a bit less and it feels like the motor is much more tame in the bottom till the intake exhaust velocity gets up there a bit. Then it starts to really charge till it's redlined. The thing is, so many builders do things different so one guys aggressive trail port is another guys dune port. Call and talk to a few different guys and see what they say matches what you want. Ask them about what you need and how they think it should be dialed in. 3 Quote Link to comment Share on other sites More sharing options...
sheerox Posted February 10, 2014 Author Report Share Posted February 10, 2014 Double dang! Thanks for such a detailed explanation. I've had my shee for about 8 months or so. Ive only ever ran it on the blacktop roads near my house so today I finally took it to an atv park (Sandhill ATV south MS) which is 300+/- acres of sandhills (i guess yall call 'em dunes out west, idk.) Anyways, on the blacktop it pulls fine throughout the gears. I guess the load the uphill sand puts on it changes all that. In first gear it would rip out the hole then, after shifting into second, it would bog momentarily (felt like lack of power or maybe too rich on the pilot) but as soon as it got a few R's up it would rip on through the powerband in 2nd np. But, 3rd wouldnt do shit; It would just bog as and drop off from there. Im pretty sure I wasnt shifting from 2nd to 3rd to soon. When i got to the atv park (while it still had turf tires on it) I took it out on some relatively flat sandy areas and went through the gears and throttle (1/4 to 3/4 to WOT etc. etc.) It bogged some out the hole so I turned the pilot screw down a half a turn, fixed that problem. The turf tires are 20 inch and sand tires i have are 21inch geckos, maybe that was part of it? Guess ill also get a 13 tooth sprocket to bring with me next and try that. Quote Link to comment Share on other sites More sharing options...
sheerox Posted February 10, 2014 Author Report Share Posted February 10, 2014 Double dang! Thanks for such a detailed explanation. I've had my shee for about 8 months or so. Ive only ever ran it on the blacktop roads near my house so today I finally took it to an atv park (Sandhill ATV south MS) which is 300+/- acres of sandhills (i guess yall call 'em dunes out west, idk.) Anyways, on the blacktop it pulls fine throughout the gears. I guess the load the uphill sand puts on it changes all that. In first gear it would rip out the hole then, after shifting into second, it would bog momentarily (felt like lack of power or maybe too rich on the pilot) but as soon as it got a few R's up it would rip on through the powerband in 2nd np. But, 3rd wouldnt do shit; It would just bog as and drop off from there. Im pretty sure I wasnt shifting from 2nd to 3rd to soon. When i got to the atv park (while it still had turf tires on it) I took it out on some relatively flat sandy areas and went through the gears and throttle (1/4 to 3/4 to WOT etc. etc.) It bogged some out the hole so I turned the pilot screw down a half a turn, fixed that problem. The turf tires are 20 inch and sand tires i have are 21inch geckos, maybe that was part of it? Guess ill also get a 13 tooth sprocket to bring with me next and try that. 1 Quote Link to comment Share on other sites More sharing options...
MarineNYC Posted February 10, 2014 Report Share Posted February 10, 2014 Aw double dang snap! U turned the pilot screw? Did you double dang adjust da udder side two? Shiz bets it rips afta dat Quote Link to comment Share on other sites More sharing options...
MarineNYC Posted February 10, 2014 Report Share Posted February 10, 2014 Just making fun of the literal double dang. Quote Link to comment Share on other sites More sharing options...
camatv Posted February 12, 2014 Report Share Posted February 12, 2014 really depends on the builder... i have seen so called "mx ports" that were little more than a clean up job.. some "dune ports" wouldn't be more than an hour from a full on drag port ( not welded). to get real low end out of a stock cylinder takes a lot longer than a decent dune/ drag port on my table.. now that being said a "real' drag port with fully welded cylinders, welded in triple exhaust ports take a lot longer. but is pretty rare these days. Quote Link to comment Share on other sites More sharing options...
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