252wheelieking Posted August 24, 2010 Report Share Posted August 24, 2010 Im about to put a +4mil in my banshee & get the cylinders ported. First of all, the kind of riding I do is high speed trail riding. After we trail ride we cut up on the street drag racing. I need some opinions on which +4mil to get for more speed/HP.(115 rods or 110mm rods) Which +4mil would give the better HP with the same porting & my set-up? How many cc/s would I have with my piston size around 64.50 with either +4mil? How much HP will either +4mil estimate be with my set-up? My current set-up is: FMF Gnarly Pipes with Power Core 2 silencers Stock head milled (.025 installed) / also have a coolhead with 21cc domes Boss Racing intake with built in crossover 34mm Keihin PJ carbs Dual K&N filter pods +4 advance timing 16T & 40T All advice/answers is highly appreicated>>>>. Quote Link to comment Share on other sites More sharing options...
vulvafan537240 Posted August 24, 2010 Report Share Posted August 24, 2010 Im about to put a +4mil in my banshee & get the cylinders ported. First of all, the kind of riding I do is high speed trail riding. After we trail ride we cut up on the street drag racing. I need some opinions on which +4mil to get for more speed/HP.(115 rods or 110mm rods) Which +4mil would give the better HP with the same porting & my set-up? How many cc/s would I have with my piston size around 64.50 with either +4mil? How much HP will either +4mil estimate be with my set-up? My current set-up is: FMF Gnarly Pipes with Power Core 2 silencers Stock head milled (.025 installed) / also have a coolhead with 21cc domes Boss Racing intake with built in crossover 34mm Keihin PJ carbs Dual K&N filter pods +4 advance timing 16T & 40T All advice/answers is highly appreicated>>>>. i would say to talk to your builder about which type of port to get. every builders portwork is different. id say a dune port since you say high speed trails and dragging. as far as the 110mm rod or 115, the 115 decreases the rod angle and side load on the piston and supposedly gives longer engine life. you will need to use 795 series pistons with the 115mm long rod. Quote Link to comment Share on other sites More sharing options...
madjimmax Posted August 24, 2010 Report Share Posted August 24, 2010 I would have to agree with volfan on this one. Give Jeff @FAST a call he does excellent work very clean. 785-364-5325 Quote Link to comment Share on other sites More sharing options...
spurdy Posted August 24, 2010 Report Share Posted August 24, 2010 As said before the 110 (stock) rod vs 115 (long) rod effects the angle between the connecting rod and the wrist pin and bearing as the piston runs up and down in the cylinder. The intention is to reduce this angle with a longer rod over the majority of the stroke. It will still come perpendicular with the piston at TDC and BDC therefore rotating through all angular sequences just at greater angles when referenced between identical heights of the stroke. As far as HP and displacement, they are the same. There maybe be some that theorize the long rod might spin up to rpm faster and this can get into a lengthy discussion as we have had on here before. I think if there was a difference in performance it would only be able to be seen in test equipment and nothing you would ever see by your "seat of the pants" dyno. Your bore size effects you displacement very little also. A 4 mil is around 390 cc and the difference in a 64mm bore and a 66mm bore is only a few cc. There used to be a graph on here that referenced bore size vs stroke length but I couldn't find it. Again, any builder would be happy to go over this with you. SP Quote Link to comment Share on other sites More sharing options...
252wheelieking Posted August 24, 2010 Author Report Share Posted August 24, 2010 As said before the 110 (stock) rod vs 115 (long) rod effects the angle between the connecting rod and the wrist pin and bearing as the piston runs up and down in the cylinder. The intention is to reduce this angle with a longer rod over the majority of the stroke. It will still come perpendicular with the piston at TDC and BDC therefore rotating through all angular sequences just at greater angles when referenced between identical heights of the stroke. As far as HP and displacement, they are the same. There maybe be some that theorize the long rod might spin up to rpm faster and this can get into a lengthy discussion as we have had on here before. I think if there was a difference in performance it would only be able to be seen in test equipment and nothing you would ever see by your "seat of the pants" dyno. Your bore size effects you displacement very little also. A 4 mil is around 390 cc and the difference in a 64mm bore and a 66mm bore is only a few cc. There used to be a graph on here that referenced bore size vs stroke length but I couldn't find it. Again, any builder would be happy to go over this with you. SP I appreicate all the help......I recently emailed Kevin @ Herrs Jugs Racing & he recommended his MX Hardcore porting for my set-up. He also said that it worked perfectly with my FMF Gnarly's. Quote Link to comment Share on other sites More sharing options...
AKheathen Posted August 24, 2010 Report Share Posted August 24, 2010 actually, it's the opposite with the 2. short rod 4mill will rev quicker and higher more easily, having more to do with better balance then a long-rod. the short-rod will also have less dwell time, and slightly different durations, resulting in more blow-down than a long-rod with the same port heights. now, trying to compare the 2 as far as power and torque is an apples-oranges scenario. they benefit better for different applications, and, like i mentioned already, will change port timing on the same set of cyls, so you can't really do a good control, but it's been researched plenty, lol. the rod angle is really not that huge of a differnce as everyone stresses. so, basically longrod should be used for more torquey builds, such as yours, from woods, to dune, and even drag, as many do, but shortrod is really best kept in the drag scene, and other topend builds. i'm sure the porting for those builds will see the end of the ring life 3 times before the slightest rod-angle related wear can be picked up. 1 Quote Link to comment Share on other sites More sharing options...
firebanshee Posted August 24, 2010 Report Share Posted August 24, 2010 I broke piston skirts with my short rod motor,but it did rev quicker.Not worth it in my opinion,i like the reliability of long rod motors. Quote Link to comment Share on other sites More sharing options...
wacko2000 Posted August 25, 2010 Report Share Posted August 25, 2010 Everyone wants a longer Rod Quote Link to comment Share on other sites More sharing options...
12 0 Clock P I M P Posted August 25, 2010 Report Share Posted August 25, 2010 Everyone wants a longer Rod Take out a Metric tape measure......5mm is the difference of the rods.......see for yourself how much it really is...not a lot... People have run reliable set up with both just have it spec'd ou prior to build and you will be fine as ong as the tolerances are within Quote Link to comment Share on other sites More sharing options...
AKheathen Posted August 26, 2010 Report Share Posted August 26, 2010 Take out a Metric tape measure......5mm is the difference of the rods.......see for yourself how much it really is...not a lot... People have run reliable set up with both just have it spec'd ou prior to build and you will be fine as ong as the tolerances are within ok, 100mm soft, 175..hard..... Quote Link to comment Share on other sites More sharing options...
WINDYCITYJOHN400 Posted August 26, 2010 Report Share Posted August 26, 2010 ok, 100mm soft, 175..hard..... You holding the rod and tape measure? Sizes might be a little off... (You know you can go blind doing that) 2 Quote Link to comment Share on other sites More sharing options...
03banshee20 Posted May 23, 2011 Report Share Posted May 23, 2011 Im about to put a +4mil in my banshee & get the cylinders ported. First of all, the kind of riding I do is high speed trail riding. After we trail ride we cut up on the street drag racing. I need some opinions on which +4mil to get for more speed/HP.(115 rods or 110mm rods) Which +4mil would give the better HP with the same porting & my set-up? How many cc/s would I have with my piston size around 64.50 with either +4mil? How much HP will either +4mil estimate be with my set-up? My current set-up is: FMF Gnarly Pipes with Power Core 2 silencers Stock head milled (.025 installed) / also have a coolhead with 21cc domes Boss Racing intake with built in crossover 34mm Keihin PJ carbs Dual K&N filter pods +4 advance timing 16T & 40T All advice/answers is highly appreicated>>>>. wanna sel that cool head? Quote Link to comment Share on other sites More sharing options...
AKheathen Posted May 23, 2011 Report Share Posted May 23, 2011 wanna sel that cool head? WTF? Quote Link to comment Share on other sites More sharing options...
camatv Posted May 24, 2011 Report Share Posted May 24, 2011 if you part it out i want the seat cover and the 2 c-clips inside the motor that hold on the shift fork shafts.. WOW~!!! short rods rev and make a broader powerband. longer rods will usually make a shorter band but can make a LIL more overall HP.. this is nothing new every motor has diff rod lengths and etc. the 115's are sometime necessary in strokers to CLEAR the crank at bottom the skirts can sometimes whack the crank at longer strokes.. but havent really had to deal with that in a LONG time.. i personally really prefer a stock stroke at 110 rod and others i dont really care. the norm is a 4 mill with longer rod its a well known setup parts are easy to get and its a very common "performance" motor.. broken skirtsis due to sloppy fitting pistons or too much piston -wall clearance. not a rod length.. i have always heard if you measure at the balls its longer.. Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted May 24, 2011 Report Share Posted May 24, 2011 I will take the crank case vent hoses Quote Link to comment Share on other sites More sharing options...
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