motocrossxr Posted September 26, 2007 Report Posted September 26, 2007 ok. So I just purchased a 1996 bansh and the original owner said that it had a 4mm crank in it. There is prot and polish work done, owner said by trail tech. It had a stock head, it did not appear to be modified at all. The pistons are stock bore wiseco pistons. Owner sai that the cases were machined to fit the 4mm crank. HAs anyone ever heard of this? Is there any way to determine if in fact I do have a 4mm crank. Quote
00tbanshee Posted September 26, 2007 Report Posted September 26, 2007 ok. So I just purchased a 1996 bansh and the original owner said that it had a 4mm crank in it. There is prot and polish work done, owner said by trail tech. It had a stock head, it did not appear to be modified at all. The pistons are stock bore wiseco pistons. Owner sai that the cases were machined to fit the 4mm crank. HAs anyone ever heard of this? Is there any way to determine if in fact I do have a 4mm crank. i have never heard of machining the cases for a 4mil crank. maybe porting them.if you have seen the head i guess you have had it off,check and see if the piston comes out of the cylinder any when its at tdc.should be around 2mm also make sure it doesn't have a spacer plate on bottom or top of the cylinder.it should have one or they other.piston out of cylinder or spacer plate Quote
dajogejr Posted September 26, 2007 Report Posted September 26, 2007 The only way to check the stroke of the crank easily is get a dial caliper and stick it in the spark plug hole. From TDC to BDC should be 58mm. If it's 54mm, it's stock stroke. As said, I've never heard of machining a set of cases for a 4 mil, it's a drop in crank. 7 to 10 mil have to be trenched, anything bigger needs to be epoxied on top and bottom, then trenched. Quote
motocrossxr Posted September 26, 2007 Author Report Posted September 26, 2007 When you say that the piston sticks out of the cylinder are you speaking about the top of the crown on the piston or the point at which the round bore diameter of the piston meets the crown of the piston? The owner said that the cases were split and they were machined then, so is it posible for the cases to be trenched for a 4mm crank? I will measure the stroke tonight and get a better idea. Since purchasing I have put a cool head on it, however have to started it at all. I have rotated the stator and nothing crashes. with 18cc domes what should the squish be? Quote
dajogejr Posted September 26, 2007 Report Posted September 26, 2007 Oh boy... If he trenched the cases for a 4 mil crank he wasted money... The reason you trench cases is to clear the lower rod bearing...which sticks out and will hit the bottom of the cases once you go larger than 4mil. Squish should change with dome cc's from where you're at now... Dome volume, however...will. I like to run .040 to .050 squish...and make sure you check it twice, on either side the left and right. You don't want to take measurements front to back, the piston will rock slightly in the bore and give a false reading. Yes...if there is no stroker plate, the piston edges where it meets the cylinder wall (you know what I mean) will stick up 2mm over deck height... Quote
motocrossxr Posted September 26, 2007 Author Report Posted September 26, 2007 Ok. It does not stick about deck height..How do you check the squirsh? I do not have a deck plate. Quote
Hilarious Posted September 27, 2007 Report Posted September 27, 2007 Ok. It does not stick about deck height..How do you check the squirsh? I do not have a deck plate. Is there evidence of the stroker plate between the cylinders and top case? Some use a plate in there. :shrug: Quote
motocrossxr Posted September 27, 2007 Author Report Posted September 27, 2007 No evidence of a plate above or below the cylinder. If the case was machined would this make it so the 4mm crank would not need a plate or different pistons? Quote
00tbanshee Posted September 27, 2007 Report Posted September 27, 2007 No evidence of a plate above or below the cylinder. If the case was machined would this make it so the 4mm crank would not need a plate or different pistons? no. as said the cases being machined just gives the rod room to clear.no matter what you have to run a spacer plate or have your head cut Quote
KEVSWS6 Posted September 27, 2007 Report Posted September 27, 2007 no. as said the cases being machined just gives the rod room to clear.no matter what you have to run a spacer plate or have your head cut If you have no spacer plate and you can rotate the motor with the new cool head on sounds like you have a stock stroke motor. Quote
chevy7398 Posted September 27, 2007 Report Posted September 27, 2007 sounds like he either got screwd and didnt know it or he really screwed you Quote
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