Mullet Man Posted February 4, 2007 Report Share Posted February 4, 2007 (edited) i cant recall reading about anyone balancing the rotating assembly in these motors. is it common practice to do this and it just doesnt get talked about or, is it just common place to run the parts "as is"? and if it isnt needed, why? Edited February 4, 2007 by Mullet Man Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted February 4, 2007 Report Share Posted February 4, 2007 I think most people just run them as they are, but yes, you can get them balanced better than they come. I'm sure some of the big name guys do it. A&S, K&T etc Quote Link to comment Share on other sites More sharing options...
FireHead Posted February 4, 2007 Report Share Posted February 4, 2007 i cant recall reading about anyone balancing the rotating assembly in these motors. is it common practice to do this and it just doesnt get talked about or, is it just common place to run the parts "as is"? and if it isnt needed, why? Because the engine is a twin cylinder with a flat plane crankshaft it is inherently dynamically balanced. Therefore you don't need balance it with a bob weight mass like you would need to 4 plane crankshaft engine. All that needs to be done is to have it trued for runout. :thumbsup: Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted February 4, 2007 Report Share Posted February 4, 2007 Because the engine is a twin cylinder with a flat plane crankshaft it is inherently dynamically balanced. Therefore you don't need balance it with a bob weight mass like you would need to 4 plane crankshaft engine. All that needs to be done is to have it trued for runout. :thumbsup: I've still seen some instances where people drilled material out of the crank webs to get them balanced. Also seen them do it for the turbo crank mod thing, but I doubt that really makes that big of a difference. Probably about like porting the cases. 1 or 2hp. But I know I've seen a few cranks that were balanced. I've never done it. Quote Link to comment Share on other sites More sharing options...
FireHead Posted February 4, 2007 Report Share Posted February 4, 2007 I've still seen some instances where people drilled material out of the crank webs to get them balanced. Also seen them do it for the turbo crank mod thing, but I doubt that really makes that big of a difference. Probably about like porting the cases. 1 or 2hp. But I know I've seen a few cranks that were balanced. I've never done it. If everything that makes up the crank (weights, pins, etc.) is true and running parallel, there shouldn't be enough of a difference for a spin balancer to pick up. The last time this topic came up, I took a couple old stock cranks to work, trued them and tried to balance them and I never could get the machine to tell me to take material off inorder to balance it. It's pretty much the best balancer out there and it gets recertified every three months, so it's a safe assumption that it was working properly. :thumbsup: I assume people have seen Banshee cranks that have been balanced because someone took it down to their local NAPA machine shop and had some pothead beat it apart, rebuild it, and then throw it on their crapmatic balancer simply because that's what they do with "all" crankshafts. That's just my theory though. Quote Link to comment Share on other sites More sharing options...
Mullet Man Posted February 4, 2007 Author Report Share Posted February 4, 2007 OK, thanks for the info. different flywheels and clutch setups doesnt have an effect on this either? what is involved in "trueing" the crank? Quote Link to comment Share on other sites More sharing options...
FireHead Posted February 4, 2007 Report Share Posted February 4, 2007 OK, thanks for the info. different flywheels and clutch setups doesnt have an effect on this either? what is involved in "trueing" the crank? Different flywheels do not matter as they should be balanced by themselves, However, this brings up an interesting question as to whether or not there a compelling reason to balance a flywheel while it''s on the crankshaft. I'm pretty sure nobody does that with Banshee cranks, but I may need to give that some thought. The clutch doesn't matter because it's not on the same axis as the crankshaft. Trueing a crankshaft means that you spin it on it's main bearings and measure the runout on the mains. The goal being that you don't want to have any runout on anything on the crankshafts center axis. I ususally true my banshee cranks to 5 microns. :thumbsup: Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted February 4, 2007 Report Share Posted February 4, 2007 yeah well I true mine to 3 microns. infinity plus one! :yelrotflmao: j/k Quote Link to comment Share on other sites More sharing options...
FireHead Posted February 5, 2007 Report Share Posted February 5, 2007 yeah well I true mine to 3 microns. infinity plus one! :yelrotflmao: j/k Oh yeah..................well then my triple can beat up your triple. j/k :yelrotflmao: Quote Link to comment Share on other sites More sharing options...
MotulMonsta Posted February 5, 2007 Report Share Posted February 5, 2007 It's not worth the money, the time and the effort to dynamically ballance a banshee crank. Wiseco cranks are pretty cheap and you can't truly rebuild a stock crank..nobody will touch it and you'll be paying more in the end when you can just drop in a trued wisco crank. Though enshuring the flywheel is ballanced would make a difference...as that weight is on the furthest part of the plane of rotation and an out of ballance flywheel could lead to premature main bearing failure and excessive vibration..but the weight of the flywheel itself doesn't matter as long as that weight is spread evenly about. The pisons and connecting rods are also important to be shure that they weight the same..as a heavy piston would cause excesive vibration..plus they should be matched to the counter weights on the crank itself. Hence why over bored banshees vibrate more then stock..the rotaing mass of the pistons are not correctly compensated by adding weight to the crank...You can't. But all this is negligable. As soon as you port a piston, it's going to be lighter anyways. Just make shure they weigh the same when you are done. If you run pistons lighter then stock..you could take some material off of the counter weights of the crank to smooth it all out. But it's not worth it. Quote Link to comment Share on other sites More sharing options...
FireHead Posted February 5, 2007 Report Share Posted February 5, 2007 It's not worth the money, the time and the effort to dynamically ballance a banshee crank. Wiseco cranks are pretty cheap and you can't truly rebuild a stock crank..nobody will touch it and you'll be paying more in the end when you can just drop in a trued wisco crank. Though enshuring the flywheel is ballanced would make a difference...as that weight is on the furthest part of the plane of rotation and an out of ballance flywheel could lead to premature main bearing failure and excessive vibration..but the weight of the flywheel itself doesn't matter as long as that weight is spread evenly about. The pisons and connecting rods are also important to be shure that they weight the same..as a heavy piston would cause excesive vibration..plus they should be matched to the counter weights on the crank itself. Hence why over bored banshees vibrate more then stock..the rotaing mass of the pistons are not correctly compensated by adding weight to the crank...You can't. But all this is negligable. As soon as you port a piston, it's going to be lighter anyways. Just make shure they weigh the same when you are done. If you run pistons lighter then stock..you could take some material off of the counter weights of the crank to smooth it all out. But it's not worth it. It is really easy to add weight to a crankshaft, either by adding weld or in high imbalance cases, heavy metal (mallory, tungsten, depleted uranium). I agree that weight matching components is important. I disagree that a big bore Banshee motor will vibrate any more than a small bore motor providing all the components are in good shape and similair in weight. Piston porting and lightening is most cases with Banshee motors is silly and a waste of time in my opinion. Plus you more than likely shorten the life of your piston and increase the likely hood of it crasking or the skirt breaking. Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted February 5, 2007 Report Share Posted February 5, 2007 It is really easy to add weight to a crankshaft, either by adding weld or in high imbalance cases, heavy metal (mallory, tungsten, depleted uranium). I agree that weight matching components is important. I disagree that a big bore Banshee motor will vibrate any more than a small bore motor providing all the components are in good shape and similair in weight. Piston porting and lightening is most cases with Banshee motors is silly and a waste of time in my opinion. Plus you more than likely shorten the life of your piston and increase the likely hood of it crasking or the skirt breaking. Everyone sends them to these guys. They did my old drag bike. Falicon Quote Link to comment Share on other sites More sharing options...
FireHead Posted February 5, 2007 Report Share Posted February 5, 2007 Everyone sends them to these guys. They did my old drag bike. Falicon Thise guys are the Scat or Eagle of the motorcycle world. They do good work for what they do, but they certainly aren't the people any of the top race teams use. Quote Link to comment Share on other sites More sharing options...
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