sled Posted November 8, 2007 Report Posted November 8, 2007 (edited) well i bought new piston from Jeff at fast to do a mild rebuild for now and i ran into some problems. i put the piston in and rotated the motor over the top of the piston popped outta the top of the cylinder. the top piston ring came out and all. does this mean it has long rods?? i was looking at it and the old head gasket is 2mm think! i also measured from the wrist pin down on both pistons and their different. theirs a 6mm difference between the old piston and the new ones. the old ones are 9.5mm from the bottom to the wrist pin and the new ones are only 3.5. from the wrist pin to the top of the piston is about 28mm on the new pistons and the old ones are about 23mm. the piston itself looks like its sticking about 5 or 6mm out the top of the cylinder. thats eye balling it . i dont have the tools to measure how far it sticks out. i thought this was a stone stock motor but i guess not. i need some help here guys! thanks Bill Edited November 8, 2007 by sled Quote
HotCarl Posted November 8, 2007 Report Posted November 8, 2007 well i bought new piston from Jeff at fast to do a mild rebuild for now and i ran into some problems. i put the piston in and rotated the motor over the top of the piston popped outta the top of the cylinder. the top piston ring came out and all. does this mean it has long rods?? i was looking at it and the old head gasket is 2mm think! i also measured from the wrist pin down on both pistons and their different. theirs a 6mm difference between the old piston and the new ones. the old ones are 9.5mm from the bottom to the wrist pin and the new ones are only 3.5. from the wrist pin to the top of the piston is about 28mm on the new pistons and the old ones are about 23mm. the piston itself looks like its sticking about 5 or 6mm out the top of the cylinder. thats eye balling it . i dont have the tools to measure how far it sticks out. i thought this was a stone stock motor but i guess not. i need some help here guys!thanks Bill It sounds like you have a 4mil stroker motor. the old pistons you have are probably blaster pistons that have a different pin to deck height (2mm) and the thick gasket is to make up the difference(2mm) therefore 4mm stroker. Quote
sled Posted November 8, 2007 Author Report Posted November 8, 2007 this is driving me up the wall. I called my buddy who builds car engines. he said he stop by tomorrow and measure the stroke for me and then he can try an figure out whats done to it. Im kinda dying to know. the bike was a flat track bike before and it has no port work. i called the guy i got it from, but he couldnt really tell me much about it. i guess it was really his kids bike not his. Quote
Handyman Posted November 8, 2007 Report Posted November 8, 2007 Can you read the numbers on the rods????might have longer rods in yours Quote
sled Posted November 8, 2007 Author Report Posted November 8, 2007 Can you read the numbers on the rods????might have longer rods in yours i think so, ill check tomorrow. im not at my shop anymore. Quote
sled Posted November 8, 2007 Author Report Posted November 8, 2007 well, i think it has a 4mm with long rods. i put one of the old pistons in to see if the piston sticks out the top and it does. without the spacer it hits the head if you just lay it on there. ive never seen a spacer that goes between the head and cylinders. does anyone know of any kits that come like that. o yeah the rods say hot rod right on the sides. Quote
dajogejr Posted November 8, 2007 Report Posted November 8, 2007 Yep, sounds like you probably have a long rod, 4 mil stroker. I've heard of spacers for the top, but most kits will sell you a spacer for the bottom. With the spacer on the top, if it hasn't been ported, the port timings are even more out of whack than just a cut head/domes and a spacer on bottom.... All the ports are lower that stock... My advice would be get the correct pistons for a stroker/long rod motor. They're called 795 series or racers choice piston. Then, get the head OR a set of domes cut for the stroker, it will run the piston up into the head....but not as much as now (as said, the right piston has a higher pin height) Your porting on the cylinders should be matched to the stroke of the motor.... Quote
sled Posted November 8, 2007 Author Report Posted November 8, 2007 (edited) thanks for the info. whats a good shop that doesnt have a waiting list?? Edited November 8, 2007 by sled Quote
dajogejr Posted November 8, 2007 Report Posted November 8, 2007 Call Bob @ R&B Racing in Michigan...very reasonable pricing... Just be flat out honest and say how long realistically before I get them back. Shit happens to everyone, but...a reasonable time frame should be quoted off the bat. 517-388-3662 Quote
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