could this cause it too...

ron89

New Member
Feb 20, 2008
2,172
15
0
35
bensalem PA..
well i pulled the motor out of the blasty today and pulled the top end off , and i was looking at the piston it seemed fine the crank was tight has no up and down play, and i was looking at the crank it it looks like the piston was hitting the case. i am thinking that is why it sounded so bad when it was running..

pic2.jpg
[/IMG]

pic3.jpg
[/IMG]

pic5.jpg
[/IMG]

pic6.jpg
[/IMG]

pic1.jpg
[/IMG]

well there is some pics of the case where it was hitting. any 1 no why the piston would be hitting??..
 
it defently looks like the piston skirt was hitting the case, it could be because of a bad wrist pin bearing since you said there was no up or down play in the crank
 
it defently looks like the piston skirt was hitting the case, it could be because of a bad wrist pin bearing since you said there was no up or down play in the crank

i was thinking the same thing but the piston hits when you turn the motor over, its just a little bit tho.

i am placing a order with vitos for .010 240 piston so i may have the bottom of it trimed down so it don't hit. but i am going to order a new wrist pin bearing too just in case haha.
 
oh yeah man, 1 more thing................stuff some wrags in the bottom end and CLEAN the cases off before u get some grit in there, if not it wont be long until u r replacing crank bearings
 
just throwin this out there...did this motor ever or is there any way it has a stroker crank in it? Reason i ask is because the case is ground in the place that it would be for a stroker crank so the connecting rod wouldnt hit...and if im thinking right a +4 stroker requires that piece of the case machined down. basically what im saying is the only way i see the piston being pulled down that far is with a stroker, either past or present. Do you know what all setups that case has been run with? and are you sure it wasnt like this before you got it? p.s. might wanna ditch that vitos super dooper stock piston lol
 
just throwin this out there...did this motor ever or is there any way it has a stroker crank in it? Reason i ask is because the case is ground in the place that it would be for a stroker crank so the connecting rod wouldnt hit...and if im thinking right a +4 stroker requires that piece of the case machined down. basically what im saying is the only way i see the piston being pulled down that far is with a stroker, either past or present. Do you know what all setups that case has been run with? and are you sure it wasnt like this before you got it? p.s. might wanna ditch that vitos super dooper stock piston lol

yea i know the case is trenched. i got the motor like that, it just has a hot rods stock stroke crank.. yea i gave the cast piston away and went with the vitos/wiseco forged piston, and i don't think it was hitting before when i got the motor, i ran it for like 5mins and tore it down sent the jug for porting and ordered up my new piston, and dropped it in my other blaster and it ran good till i blew out a base gasket and its been doing it ever since, it just got louder and louder....
 
so does any one no why my piston would hit on the case like that cause every thing is tight the wrist pin bearing is tight no up and down play. but the crank does have some side play like if you take the piston off the crank and push the top of the crank /connecting rod and push the top where the wrist pin bearing gos it will move maybe a millimeter to the left and right is that normal..
 
yeah the side to side play is normal, how does the bore/piston look? if the rings are bad it could allow the piston to move sideways somewhat and the skirt hit like that, make sence? like instead of being aligned with the cylinder it could be angled a bit..
 
yeah the side to side play is normal, how does the bore/piston look? if the rings are bad it could allow the piston to move sideways somewhat and the skirt hit like that, make sence? like instead of being aligned with the cylinder it could be angled a bit..

the bore is pretty good you can see some wear marks on the cylinder, but it had awesome compression it would start fist kick pretty much every time. i guess when i get the new piston ill take it to a machine shop and have them take like a millimeter off the bottom of my piston so it don't hit.
 
thats weird ... sh*tt like this will bug me till i figure out what it is... ive never heared of anyone else having this problem with this set up...
 
if your bearings are all tight only thing i can think of is a bad lemon of a piston even the addition of a stroker would not do this in that area .btw clean all that yama bond gunk overhung out of your cases and ru n a cometic copper or steel base gasket and it wont ever blow out
 
if your bearings are all tight only thing i can think of is a bad lemon of a piston even the addition of a stroker would not do this in that area .btw clean all that yama bond gunk overhung out of your cases and ru n a cometic copper or steel base gasket and it wont ever blow out

yea i am going to clean it all up. its hard to say if the piston was bad i don't think it was cause i didn't hear any noise when i did break in, but i am going to order a 010 over forged piston with all new gaskets and wrist pin bearing when i get them ill install them, and if it hits the case when i rotate the crank then ill have the bottom of the piston milled down a little i guess lol..
 
well i got the parts from vitos today, and i just put the piston on new wrist pin bearing and cranked the motor till the crank was at BDC, and the piston still hit very little should i file a little off the piston skirt or when i drop the piston off at the machine shop have them mill it down maybe a mm or so?..