Ayesully810 Posted February 6, 2019 Report Share Posted February 6, 2019 41 minutes ago, specialblend07 said: It’d be awesome if someone with a clue chimed in Sent from my iPhone using Tapatalk true. I never knew my engine was a shape. im the most lost. wait what thread is this? Quote Link to comment Share on other sites More sharing options...
registered user Posted February 6, 2019 Report Share Posted February 6, 2019 5 hours ago, ZillaFreak said: A larger bore can mean wider ports in the cylinder wall. How is square the best compromise? TRX250R, LT250R, CR250R and most bikes are all undersquare. Quadzilla is square. Banshee and CR500 are oversquare. So which engine is the best, the quadzilla engine because it is square? As for the banshee being oversquare because it is cheaper and less machine work to go up in pistons than stroke.... how does this equate for yamaha when designing? the ports get wider (more area) with bigger bore but not at the same proportion as longer stroke years ago some of the 250 were sqaure. why theyre undersqaure now seems kind of a mystery. ive talked to knowledgable people about it but theres mostly just speculation for answers. maybe it gave a favorable powerspread. maybe chassis handling was better. a email to one of the bike manufacturers might solve the mystery if u could get in touch with the right person i think the banshee stemed from a street bike engine so you would have to ask why did that streetbike need oversqaure. my guess is a more compact package. given the cylinders are sqaushed together also, this makes the most sense to me. Quote Link to comment Share on other sites More sharing options...
ClaudeMachining Posted February 6, 2019 Report Share Posted February 6, 2019 true. I never knew my engine was a shape. im the most lost. wait what thread is this?Then listen and read.Envoyé de mon SM-G965W en utilisant Tapatalk Quote Link to comment Share on other sites More sharing options...
registered user Posted February 6, 2019 Report Share Posted February 6, 2019 13 hours ago, sheerider11 said: I remember back in the day this came up. I think I remember some one saying the square engines just wouldn't be as efficient as the others. This was when people cared and had better conversations tho. Sent from my SAMSUNG-SM-G891A using Tapatalk im sure u could make a valid arguement for each side of the fence (oversqaure, sqaure, undersqaure) but at the end of the day sqaure is generally regarded as the best compromise in hiperf 2stroke. mechanically ,oversqaure may b better suited to high rpm but u lose valuable port area (breathing ability) vs sqaure,/undersqaure. i think the main problem with undersqaure , although it may breath well, u may end up with excessively high piston speeds which could limit rpm , perhaps it may have more friction loss also Quote Link to comment Share on other sites More sharing options...
ZillaFreak Posted February 6, 2019 Report Share Posted February 6, 2019 12 hours ago, registered user said: the ports get wider (more area) with bigger bore but not at the same proportion as longer stroke years ago some of the 250 were sqaure. why theyre undersqaure now seems kind of a mystery. ive talked to knowledgable people about it but theres mostly just speculation for answers. maybe it gave a favorable powerspread. maybe chassis handling was better. a email to one of the bike manufacturers might solve the mystery if u could get in touch with the right person i think the banshee stemed from a street bike engine so you would have to ask why did that streetbike need oversqaure. my guess is a more compact package. given the cylinders are sqaushed together also, this makes the most sense to me. Oversquare means bigger bore than stroke. So saying the banshee is oversquare because the cylinders are squashed together is complete false. If yamaha wanted the cylinders close together, it would be undersquare aka longer stroke than bore. The fact are, a shorter stroke allows for higher revs, hence why most high revving engines are oversquare. A longer stroke allows for more torque, hence why most workhouse engines are undersquare. Quote Link to comment Share on other sites More sharing options...
registered user Posted February 6, 2019 Report Share Posted February 6, 2019 mechanically , the further oversqaure, the better it would lend itself to higher revs. we see it in f1 like has been said. but u seem to not be able to understand 2stroke doesnt work in the same way. the further over sqaure u go, the larger the difference between port area of sqaure vs oversqaure. bottom line, oversqaure ends up with less port area, the further it goes away from sqaure. it doesnt make a fuk of difference if mechanically the engine is safe to 40k rpm , if it cant breath then its all for nothing. sorry if i cant explain it easier than that Quote Link to comment Share on other sites More sharing options...
registered user Posted February 7, 2019 Report Share Posted February 7, 2019 wow there sure is alot of bullshit on the net. some clown on a rc airplane site says the oversqaure will meen smaller crankcase and thus more efficient pumping at higher revs. smaller crankcase will have higher peak pressure and thus more pumping loss. i believe that would be no different than pumping loss that happens as compession ratio goes up Quote Link to comment Share on other sites More sharing options...
n2otoofast4u Posted February 7, 2019 Report Share Posted February 7, 2019 In the past square motors worked great, were typically reliable, and make great power. For instance look how many 78 x 78 DMs are around that fkn rip!! Now 5 years ago the performance seemed to drop off once you got out of square on the stroke side, when the stroke was bigger. They just didn't seem to work as well as the square stuff or the stuff out of square in the opposite direction. And as a rule of thumb, I would say that holds true in most applications to this day. BUT there are a few out of square motors on the stroke side running around that FKN fly, but those are typically owned by very experienced owners and built by very experienced builders. And there are limits to how far out of square remains successful. 54 x 78..... didn't work great. 58 x 78 is a fkn riot.... Quote Link to comment Share on other sites More sharing options...
ClaudeMachining Posted February 7, 2019 Report Share Posted February 7, 2019 In the past square motors worked great, were typically reliable, and make great power. For instance look how many 78 x 78 DMs are around that fkn rip!! Now 5 years ago the performance seemed to drop off once you got out of square on the stroke side, when the stroke was bigger. They just didn't seem to work as well as the square stuff or the stuff out of square in the opposite direction. And as a rule of thumb, I would say that holds true in most applications to this day. BUT there are a few out of square motors on the stroke side running around that FKN fly, but those are typically owned by very experienced owners and built by very experienced builders. And there are limits to how far out of square remains successful. 54 x 78..... didn't work great. 58 x 78 is a fkn riot.... Wtf are you doing in a technical discussion??? ;-)Envoyé de mon SM-G965W en utilisant Tapatalk Quote Link to comment Share on other sites More sharing options...
SKEETER Posted February 7, 2019 Report Share Posted February 7, 2019 Trying to give real world advice to ppl that think they know alot more than they really do, about banshee engines :shrug: Quote Link to comment Share on other sites More sharing options...
specialblend07 Posted February 7, 2019 Report Share Posted February 7, 2019 6 minutes ago, SKEETER said: Trying to give real world advice to ppl that think they know alot more than they really do, about banshee engines :shrug: Welcome to BHQ. It's the WebMD of the ATV world. Quote Link to comment Share on other sites More sharing options...
ClaudeMachining Posted February 7, 2019 Report Share Posted February 7, 2019 Trying to give real world advice to ppl that think they know alot more than they really do, about banshee engines :shrug: Welcome to BHQ. It's the WebMD of the ATV world. You both gay.Envoyé de mon SM-G965W en utilisant Tapatalk Quote Link to comment Share on other sites More sharing options...
SKEETER Posted February 7, 2019 Report Share Posted February 7, 2019 Still better than being ...........canadian 1 Quote Link to comment Share on other sites More sharing options...
ClaudeMachining Posted February 7, 2019 Report Share Posted February 7, 2019 Still better than being ...........canadianIm a Quebecer first, a separatist, dont forget it ;-) Envoyé de mon SM-G965W en utilisant Tapatalk Quote Link to comment Share on other sites More sharing options...
BANSHEE HP Posted February 8, 2019 Report Share Posted February 8, 2019 I did a 421 58x68 and a 424 64x65 this past season. The 421 made 2hp more than the 424. Ported very similar but I would say the 421 had a touch more work. Quote Link to comment Share on other sites More sharing options...
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