SLORYDER Posted June 2, 2010 Report Share Posted June 2, 2010 (edited) First let me start off by saying Please don't post if you read from some guy on the forum that the intake sucks if you have no idea how a banshee engine operates. From what I understand 90% of you can't even tighten your chains so please don't give me your brainwashed babble. OK. I've been thinking about this. The cylinders are 180 degrees out of phase, so theoredically only one cylinder is pulling charge at a time. What this theort suggests is that one 35mm carb would perform the same function as two BUUUUUUT What is happening inside the cylinder that isn't sucking? It appears that it would be putting a positive pressure on the reed cage area as it drops during the transfer phase. Now would this be benificial to the other cylinder trying to suck, or would it put back pressure on the carb to the extent that it places resistance against the intake charge? Edited June 2, 2010 by SLORYDER Quote Link to comment Share on other sites More sharing options...
Duneman101 Posted June 2, 2010 Report Share Posted June 2, 2010 no, there isn't back pressure from the nonfiring cylinder, that is stopped by the reeds, as far as 1 35 mm carb acting as two, it's probably close but i don't think the pull is quite enough to equate to that, remember that the cylinder is pulling the length of the intake tract, and remember that the fork in the intake is putting air/fuel into two tracts not just one, i am no scientist, but i would be inclined to believe that a good portion of the air/fuel mix is heading down the right tract at the right time, but probably not the entire amount. Quote Link to comment Share on other sites More sharing options...
hercalmighty Posted June 2, 2010 Report Share Posted June 2, 2010 At low rpms the single carb works great because the carb has a chance to "recharge" between the two cylinders. As the rpms increase the pistons are moving so fast that the carb has to feed both cylinders almost at the same time. Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted June 2, 2010 Author Report Share Posted June 2, 2010 (edited) no, there isn't back pressure from the nonfiring cylinder, that is stopped by the reeds Yeah but if the other cylinder is drawing mix the reeds are open... Edited June 2, 2010 by SLORYDER Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted June 2, 2010 Author Report Share Posted June 2, 2010 At low rpms the single carb works great because the carb has a chance to "recharge" between the two cylinders. As the rpms increase the pistons are moving so fast that the carb has to feed both cylinders almost at the same time. Yeah but even if they stopped pulling at the exact time the other started pulling, the carb would just be constantly"on" and shouldn't have a problem, unless there is overlar of the two intake cycles Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted June 2, 2010 Author Report Share Posted June 2, 2010 After more thought, it seems like the side that is suching would actuall pull some charge out of the other cylinder as it is trying to force it through the transfers. Doesn't seem like it would let the transfer phase be as efficient. Quote Link to comment Share on other sites More sharing options...
mikechief Posted June 3, 2010 Report Share Posted June 3, 2010 If you think of the mix as water I would think that the manifold would be full all the time provided you have a big enough carb the higher the rpm the better Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted June 3, 2010 Author Report Share Posted June 3, 2010 (edited) If you think of the mix as water I would think that the manifold would be full all the time provided you have a big enough carb the higher the rpm the better After thinking more about this, it appears that there may be minimal overlap of the intake cycle of the two cylinders, however it shouldn't be enough to make a significant differende, miiiiight make it seem like a pair of 33's instead of 35's. IMO. The thing that bothers me is the fact that when one cylinder is in the transfer phase and pressurizing the reed cage area, instead of building pressure to push the transfer stream through the flow follows the path of least resistance and goes into the other cylinder. Unless of course there is a check valve in each intake runner separating the two sides...Is there? Edited June 3, 2010 by SLORYDER Quote Link to comment Share on other sites More sharing options...
streakx Posted June 3, 2010 Report Share Posted June 3, 2010 (edited) Yeah but if the other cylinder is drawing mix the reeds are open... Incorrect .. lets say cyl#1 is breathing (cyl#1 reeds are open) and cyl#2 ain't breathing (cyl#2 reeds are closed) ect ect ... you still have 2 reed cages to operate right ... there's no interference between the two cages. IMO ... one of the reasons the 2in1 setup works better in the lower powerband is because of the distance of the carb from the cylinders (created by the manifold) .. so it act like a bigass reed spacer wich create more response, better low/end, less revs. Plus don't forget you're messing with velocity when you have to deal with a cross feeding manifold. My buddy had a 35mm single carb setup from trinity and i DID TRY the before(twin stockers/after(single35mm) ... it was pulling much stronger on low/mid range and had around the same on top (maybe a lil better)... but again he had stockers before trying the single setup. I don't know how it would compare from, let's say, twin 35mm and single 38mm .. i would like to see this with my own eyes Chris Edited June 3, 2010 by streakx Quote Link to comment Share on other sites More sharing options...
mikechief Posted June 3, 2010 Report Share Posted June 3, 2010 After thinking more about this, it appears that there may be minimal overlap of the intake cycle of the two cylinders, however it shouldn't be enough to make a significant differende, miiiiight make it seem like a pair of 33's instead of 35's. IMO. The thing that bothers me is the fact that when one cylinder is in the transfer phase and pressurizing the reed cage area, instead of building pressure to push the transfer stream through the flow follows the path of least resistance and goes into the other cylinder. Unless of course there is a check valve in each intake runner separating the two sides...Is there? Wouldn't the check valve be the reeds ? I have a graydon and that's totally different than trinity. Better ? Idk. snop-shiz-in-ski says they're all junk and has charts to prove it Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted June 3, 2010 Author Report Share Posted June 3, 2010 (edited) Wouldn't the check valve be the reeds ? I have a graydon and that's totally different than trinity. Better ? Idk. snop-shiz-in-ski says they're all junk and has charts to prove it Incorrect .. lets say cyl#1 is breathing (cyl#1 reeds are open) and cyl#2 ain't breathing (cyl#2 reeds are closed) ect ect ... you still have 2 reed cages to operate right ... there's no interference between the two cages. IMO ... one of the reasons the 2in1 setup works better in the lower powerband is because of the distance of the carb from the cylinders (created by the manifold) .. so it act like a bigass reed spacer wich create more response, better low/end, less revs. Plus don't forget you're messing with velocity when you have to deal with a cross feeding manifold. My buddy had a 35mm single carb setup from trinity and i DID TRY the before(twin stockers/after(single35mm) ... it was pulling much stronger on low/mid range and had around the same on top (maybe a lil better)... but again he had stockers before trying the single setup. I don't know how it would compare from, let's say, twin 35mm and single 38mm .. i would like to see this with my own eyes Chris OK. I was thinking there was only a single reed cage for the two cylinders. Now it makes sense. So the only factor here would be the overlap between the two carbs, which IMO would be minimal. I would like to hear sodapopinski's opinion on why the setup does not work and the associated dyno sheets. Edited June 3, 2010 by SLORYDER Quote Link to comment Share on other sites More sharing options...
mikechief Posted June 3, 2010 Report Share Posted June 3, 2010 Windycityjohn where are you ? Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted June 3, 2010 Author Report Share Posted June 3, 2010 (edited) delete Edited June 3, 2010 by SLORYDER Quote Link to comment Share on other sites More sharing options...
mikechief Posted June 3, 2010 Report Share Posted June 3, 2010 Jetting is obviously easier with a single carb as far as labor goes. But how bout accuracy? Would that affect dyno results? Quote Link to comment Share on other sites More sharing options...
Chariot Performance Posted June 4, 2010 Report Share Posted June 4, 2010 At high rpms both reed cages are constantly open. If you have your air filters off and rev the bike with two carbs you can feel the air flow out of the carb on the filter side. You can also see the air fuel mix. Quote Link to comment Share on other sites More sharing options...
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