WHAT SHALL I DO GO STROKER OR BIG BORE

[Cotton eyed Joe]

I'm not too certain about the effects strokers have on the banshee setup. however... In automotive applications strokers do not usually turn the RPM's that unstroked motors will.  IE the reason why you generally get more Torque, but not as much peak HP out of a stroker, since HP is essentially Torque over time (added RPM).  So all else the same, you would not get the RPM out the stroker.  Again my knowledge of stroker setups come from auto apps. In theory should be the same, but maybe I'm all wet?

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HP=(TQxRPM)/5252

 

I've seen some methanol powered ice racers (some sort of oval track) in a magazine a while back that actually had the stroke shortened to get more rpm out of the engine. Torqueless wonders, but I guess they served a purpose.

[Meat]

'm not too certain about the effects strokers have on the banshee setup. however... In automotive applications strokers do not usually turn the RPM's that unstroked motors will. IE the reason why you generally get more Torque, but not as much peak HP out of a stroker, since HP is essentially Torque over time (added RPM). So all else the same, you would not get the RPM out the stroker. Again my knowledge of stroker setups come from auto apps. In theory should be the same, but maybe I'm all wet?

 

Interesting.

 

 

 

Anyone care to comment on the small transfer port problem that big bore motors have. I don't think that issue was ever settled.

Edited October 7, 2005 by Meat

[Meat]

HP=(TQxRPM)/5252

 

I've seen some methanol powered ice racers (some sort of oval track) in a magazine a while back that actually had the stroke shortened to get more rpm out of the engine. Torqueless wonders, but I guess they served a purpose.

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Stan no doubt about those ice racers...... Thats the first thing I thought of when I read 2003LimitedBanshee post. shortened the stroke for more rpms. Its just like the modern 4 stroke engine, they engineer these motors to be "square", meaning they have a similar bore and stroke size, the reasoning for this design is to produce a high revving engine. modern crotch rocket is red lining at14,000 rpm. Another example would be the modern compact import sports cars, Honda Civics and Acuras.... hi rpm motors.

[sandman121383]

i with meat u guys,and stand and limitedshee. i agree. the stroker really can't make the rpms. yamaha bored the 450 .10 over and did the same to the raptor. the comparison to the auto world is what makes it intriging. i'm curious about the port too now that meat mentioned it. anyone?

[PassionRE]

i with meat u guys,and stand and limitedshee. i agree. the stroker really can't make the rpms. yamaha bored the 450 .10 over and did the same to the raptor. the comparison to the auto world is what makes it intriging. i'm curious about the port too now that meat mentioned it. anyone?

423794[/snapback]

Stock bore and stroke configurations of the Banshee are 64x54. Bore to stroke ratios are well under square configuration to begin with so even adding 4mm to the stroke it still us under square configuration in reference to stroke. Stroking to this level isnt what keeps rpm's down, its the motors capability of flowing enough fuel/air without compensating for it in porting that does this. 4mm motors will rev to the moon when set up for it.

As for big bore transfer inadequacy without mods to ports, definately. Transfer operational efficiency range on a stock Banshee's transfer ports on a bone stock engine, are 5600-10700 rpm. Bore the engine to just 68mm and those numbers change to 5000-9600rpm. Power moved down with little increase if any in peak hp. Raise the transfers just 1mm and these specs change to 5700-10700rpm without ex. mods. Exhaust area needs enlarged as well or blowdown psi will drop from 143 to 129...yes even big bores need adjusting on ports, just like strokers....Jim

[Banchetta]

I have a 4mm stroker and my builder told me that I'd lose peak rpm..Well, he was wrong. I pull the same rpms as before. I actually expected more out of my stroker when I had it done, but oh well, time to get more!!! I know Paul (99nhbanshee) has a 420 big bore in his shee. He would launch it from a dead start in 3rd gear and grab 4th going up a hill no more than 70'. I was very impressed w/ his big bore setup...Before I did my motor, I was eyeing the stroker for some time. Duncan actually suggested for me NOT to build one for my type of riding and suggested the stroker for high speed riding only. He claimed he could get more performance out of a stock stroke for coming out of the corners, mx, on/off throttle applications. He claimed the stroker only had the advantage for like Pikes Peak, oval racing, drag, etc... I've seen ported stock stroke banshees go very well and impressive.

[Meat]

Stock bore and stroke configurations of the Banshee are 64x54. Bore to stroke ratios are well under square configuration to begin with

 

very good point. advantage stroker.

[wayfst]

As you see in my sig. I have a big bore stroker. The thing to keep in mind is that not one thing is going to be the " silver bullet ", it's a combo of everything. a buddy that rides with my group has a stock motor, ported with pipes. He weighs 40 pounds less than I do, my bike is a 100 cc bigger than his, if I don't use the NOS he wins. he has the right combo for his weight. When I went to the four mill I didn't feel the hit I expected, same with the 7 mill, but 68.5 mm pistons, reeds, the right head, the right cdi box, adjusting the timing, the proper fuel, on and on. now atfer 5 motors and thousands of dollars I can almost do what a 160 pound guy can on a stock motored banshee. look for the right combo, maybe it's not a stroker or a big bore.

[3ban5shee0]

i put a stroker kit in mine one ofthe first things i did and im glade i did alot of people told me that all a stroker kit does is make you work on your banshee more but i havent had any problem with it

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b ig bore stroker , do both

[badassbanshee479]

68mm 4mill cubs and be done with it!!! hard to catch with stock cylinders

[RNBRAD]

Someone please tell me a downside of running a 4mil stroker crank. It can't be all good, there has to be a tradeoff when you stroke um, slower revving maybe, peakier dyno runs.... there has to be a scientific verifable disadvantage of a stroker crank  .

 

I personally can't think of one disadvantage. Slower revving is a possibility but I don't see that it's a disadvantage when typically the stroker will make more power at a lower rpm than a stock stroke will. (example) If a stroker starts building power at 5k and end at 9.5k and a stock stroke builds power at 6k and ends at 10.5k. Is there an advantage of one over the other even if both produce the same peak hp? I'm sure there is also a "time factor" per say that it takes a motor under a certain load to rev through those rpm ranges.