endofitall9 Posted October 8, 2005 Report Posted October 8, 2005 I agree, boring your cylinders isnt going to do much if anything but the fact is that boring you cylinders has nothing to do the the CC the CC is the distance between the the piston crown and the and the bottom of the head. the Squish forces fuel mixture what not in the the cc and causes explosions So the tighter the CC is the more efficient the fuel will burn thus creating more power and can cause detonation due to low octane. All Im saying is that the combustion chamber has nothing to do with boring cylinders. Boring the cylinders really is just a poor mans way of getting around resleeving them. Butit does work just as good Quote
2003LimitedBanshee Posted October 8, 2005 Report Posted October 8, 2005 I agree, boring your cylinders isnt going to do much if anything but the fact is that boring you cylinders has nothing to do the the CC the CC is the distance between the the piston crown and the and the bottom of the head... So the tighter the CC is the more efficient the fuel will burn thus creating more power... All Im saying is that the combustion chamber has nothing to do with boring cylinders 424142[/snapback] Actually, I think you're confusing a few concepts here. Boring does cange the displacement, in the case of Banshees measured in CC (cubic centimeters). As you increase your bore you increase displacement, as displacement the result of bore and stroke (and pi etc.). What you are talking about is the volume of the combustion chamber, which will be affected by increasing bore as well. When you bore, the displacement of the bike will change (ie. greater than 347cc), but the CC of the combustion chamber will increase also. This is why you should also looked at having your head milled as well. Essentially, the area you are compressing the air/fuel mix into will increase also, lowering compression. Depending on the amount of overbore it may not be noticeable, but the formula for calculating how much compression will drop gets complicated because you are actually forcing more air (due to increased displacement) into a somewhat larger space, soo.... Quote
2003LimitedBanshee Posted October 8, 2005 Report Posted October 8, 2005 pk so your saying that making the CC smaller doesnt raise compression and allow for stronger explosions? If that is is then why is it when you put smaller domes in your head the compression goes up. 424009[/snapback] The reason why is because manufacturers are talking about the CC of domes, they aren't actually referring to the size of the dome, they are talking about the size of the combustion chamber you will be left with. Someone correct me if I'm wrong, but Banshee's are a zero deck engine, meaning the piston comes dead even with the top of the block (jug), those the CC of your combustion chamber is set in the dome of the stock or aftermarket head. So a smaller CC dome (as quoted by manufacturers) is actually a lager insert, giving you a smaller CC combustion chamber, ie. same amount of air compressed into a smaller area ==> higher compression. Point I'm getting at is smaller domes (CC) are actually bigger in physical size so that the volume of the dome you are left with in the combustion chamber is smaller. Quote
fast500#12 Posted October 11, 2005 Author Report Posted October 11, 2005 if bore doesn't do that much then why is a 250r bored to a 310 so much faster than a stock bore. i under stand that there is more mechanical leverage on a stroker and the displacement does change when you stroke a motorand gives it more hp. but i just say that it must do a considerable amount because all the really fast bikes arn't just 350 strokers. thanks guys this has turned out to be a very informative topic. Quote
locogato11283 Posted October 11, 2005 Report Posted October 11, 2005 if bore doesn't do that much then why is a 250r bored to a 310 so much faster than a stock bore. i under stand that there is more mechanical leverage on a stroker and the displacement does change when you stroke a motorand gives it more hp. but i just say that it must do a considerable amount because all the really fast bikes arn't just 350 strokers. thanks guys this has turned out to be a very informative topic. 424804[/snapback] no such thing as a 350 stroker..anytime you stroke you get more cc's...so take a 350 and add 4mm stroke you arent at 350 anymore... Quote
Shee-Male Posted October 11, 2005 Report Posted October 11, 2005 if you have to bore/hone you engine, it dosn't mean you have to mill your cyl. head, the replacement piston dome is corrected by the factory so the squish stays the same. Also remember if you have a 350cc and you bore it .040, it dosn't make it a 390cc. Taking stock cyl's to the max on a first rebuils is just stupid, you're simply ruining a good set of jugs! Quote
dave95.1 Posted October 11, 2005 Report Posted October 11, 2005 no such thing as a 350 stroker..anytime you stroke you get more cc's...so take a 350 and add 4mm stroke you arent at 350 anymore... 424823[/snapback] I think he's talking about Honda here, I think you can make a 250R a 350 by boring and stroking it. you guys say "stroke it" too much Quote
locogato11283 Posted October 11, 2005 Report Posted October 11, 2005 I think he's talking about Honda here, I think you can make a 250R a 350 by boring and stroking it. you guys say "stroke it" too much 424935[/snapback] oh ok... Quote
trex banshee Posted October 12, 2005 Report Posted October 12, 2005 I think he's talking about Honda here, I think you can make a 250R a 350 by boring and stroking it. you guys say "stroke it" too much 424935[/snapback] when he says a 350 stroker i took it as a stock bore banshee(350cc) with a 4 mill stroker. yeh i know it isn't a 350 anymore because of the stroker but i think it was easier to explain a banshee with 64mm pistons and a 4mm stroker instead of saying a 3?? or whatever a stock bore 4mil stroker makes the cc. may be wrong but that is the way i took it. Quote
fast500#12 Posted October 12, 2005 Author Report Posted October 12, 2005 (edited) that is the way that i ment it. i am talking about banshees. i do know that when the stroke changes it canges the displacement. i didn't know that the long rods were off set 2mil from stock rods so most things make sense now. i believe that when you do the 4mil it makes your total displacement some where around 400cc. i could be wrong because changing your bore 1mil or .040 makes it a 390cc. there is no posible way that i would ever take the jugs out to .100 on the first bore, that is just retarded. Edited October 12, 2005 by fast500#12 Quote
blueshee03 Posted October 13, 2005 Report Posted October 13, 2005 a motor with a stock bore of 64mm and a 4 mil stroker crank would be a 373cc motor. 65mm with a 4 mil stroker crank is a 385. . 66mm [80 over] +4 mil =397cc 68mm blaster pistons+4 mil stroker=421cc Quote
trex banshee Posted October 13, 2005 Report Posted October 13, 2005 i could be wrong because changing your bore 1mil or .040 makes it a 390cc. no you are still wrong just boring your shee 40 over with a stock stroke crank does not make it a 390. It is probably somewhere around 350-355-360 i am not to sure but i do know that it doesn't make it a 390 Quote
blueshee03 Posted October 13, 2005 Report Posted October 13, 2005 (edited) stock stroke with a .40 overbore is a 358.thats what mine is now.the formula to figure your motor size is : bore x bore x stroke x no. of cylinders x .7854 devided by 1000 Edited October 13, 2005 by blueshee03 Quote
trex banshee Posted October 13, 2005 Report Posted October 13, 2005 that is what i thought because mine is stock stroke with 68mm bore and it is a 400 Quote
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