gregrob Posted June 9, 2010 Report Share Posted June 9, 2010 Who has done this and did the universe collapse on itself when you did? I have a set of cases ported for my 4mil twister and I'm thinking about just putting the top case half and topend on my HJR engine. Should I do that, or just swap the entire transmission and everything? Word Quote Link to comment Share on other sites More sharing options...
toytech Posted June 9, 2010 Report Share Posted June 9, 2010 Who has done this and did the universe collapse on itself when you did? I have a set of cases ported for my 4mil twister and I'm thinking about just putting the top case half and topend on my HJR engine. Should I do that, or just swap the entire transmission and everything? Word the case halfs are machined to match each other, you need to use the matching case halfs together or things don't lineup properly. I'm not saying it can't be done but it won't be the rite way to do it. Quote Link to comment Share on other sites More sharing options...
NYUK Posted June 9, 2010 Report Share Posted June 9, 2010 it`s a crap shoot, it can make the crank bearings fail prematurely. i avoid it if possible. Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted June 9, 2010 Report Share Posted June 9, 2010 Just swap the jugs, less work , no problems. Quote Link to comment Share on other sites More sharing options...
bansheesandrider Posted June 9, 2010 Report Share Posted June 9, 2010 Yamaha did the final machining on the cases as a set. All the bearing bores for the crank and transmission shafts are machined to final dimension with the cases bolted together. That is why Yamaha only sells Banshee cases as a set. Some guys say they can be mix and matched, but I think that will lead to other problems down the road. Quote Link to comment Share on other sites More sharing options...
firebanshee Posted June 9, 2010 Report Share Posted June 9, 2010 Matched is better,but i have mix them without problems on several occasions. Quote Link to comment Share on other sites More sharing options...
Zeroskill Posted June 9, 2010 Report Share Posted June 9, 2010 Its like sticking your head in an alligator's mouth. Possible, but very dangerous. Quote Link to comment Share on other sites More sharing options...
gregrob Posted June 10, 2010 Author Report Share Posted June 10, 2010 Just swap the jugs, less work , no problems. Not possible. If it was that's obviously what I'd do. The smallblock twister cylinders require the top case half to be bored to accept the larger sleeves, and the case porting wouldn't even be close. I already have a set of cases ported for the twister, just didnt want to hassle with swapping the tranny and entire bottom end out of the other ones, but I suppose I will take the time to avoid any issues. I would still like to hear of where this caused a problem though. Everyone says "dont do it the universe will explode" but I have never heard of anyone having problems from it. Quote Link to comment Share on other sites More sharing options...
dco3100 Posted June 10, 2010 Report Share Posted June 10, 2010 If the manufacturer produces "identical" parts for these "different" cases, then there would be no medium for the fitment among every engine part designed for the model. Basically, if Yamaha made cases different in any way, it would mean that the "crank bearings" as mentioned not line up properly or whatever the case for a particular set(s. Ive heard the universe will blow up story as well, but both of my bikes have diff case halves and I havent had any problems Quote Link to comment Share on other sites More sharing options...
gregrob Posted June 10, 2010 Author Report Share Posted June 10, 2010 If the manufacturer produces "identical" parts for these "different" cases, then there would be no medium for the fitment among every engine part designed for the model. Basically, if Yamaha made cases different in any way, it would mean that the "crank bearings" as mentioned not line up properly or whatever the case for a particular set(s. Ive heard the universe will blow up story as well, but both of my bikes have diff case halves and I havent had any problems True. The thing I've heard that makes the most sense is that the case halves are line bored for the crank bearings and if one set was off enough from another, you could have problems. I would think you could see the discrepancy there if it was big enough to put enough pressure on the bearing cages to cause a failure. JMO though Quote Link to comment Share on other sites More sharing options...
okbeast Posted June 10, 2010 Report Share Posted June 10, 2010 We've had some that wouldn't even fit together, so that tells me not to try it. Quote Link to comment Share on other sites More sharing options...
stroking Posted June 10, 2010 Report Share Posted June 10, 2010 well i have mixed them and they worked fine,and also have tried to mix others and it not work i had one that when you tight down the cases together the tranny would become hard to turn over....so i switched the cylinders to the matching cases and it worked find would. so some will work and some won't. Quote Link to comment Share on other sites More sharing options...
Erwin8r Posted June 10, 2010 Report Share Posted June 10, 2010 Dude, it's like cam-caps and heads on a DOHC 4-poker... Sometimes (maybe many times) you'll get away with using unmatched sets, but it is not the right thing to do. I'd put the work in... Quote Link to comment Share on other sites More sharing options...
bansheesandrider Posted June 11, 2010 Report Share Posted June 11, 2010 (edited) We've had some that wouldn't even fit together, so that tells me not to try it. When Yamaha line bores the holes for the bearings, the parting line is not always perfectly in the center of the hole. If you mix a top that was offset to the top with a bottom that was offset to the bottom they wont go together. If you use a top that was offset to the bottom with a bottom that was offset to the top then the bearings will be loose in the bores. Granted, we are talking about ten thousandths of an inch but it does matter. Any good mechanic knows that you need to keep bearing caps in their original machine location or you COULD have problems, whether it is main bearings, differential bearings or overhead cam bearings. Edited June 11, 2010 by bansheesandrider Quote Link to comment Share on other sites More sharing options...
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