if i bored my atv 20 over and didnt jet will that cause the piston to hit the valves?

 

No. Boring has nothing to do with valve to piston clearance. And jetting REALLY has nothing to do with valve to piston clearance.

 

well my piston it hitting the head

 

Did you use stock size head gasket or the OS (over size) head gasket .. Your piston is probably touching the head gasket ..

 

<div class="FTQUOTE"><begin quote>will that cause the piston to hit the valves? </end quote></div>
<div class="FTQUOTE"><begin quote>well my piston it hitting the head </end quote></div>
Did the piston hit the head or the valves? BIG difference.

If the piston hit the valves: It could be:
#1 Excessive piston to bore clearance.
#2 Wrong piston.
#3 Excessive wrist pin to piston clearance.
#4 Bad con rod bearing.
#5 Wrong cam timing.
#6 Too big of cam.
#7 Wrong head/base gasket crush.
#8 Too much taken material taken off of head (That's all I can think of now!!)

If the piston hit the head: It could be:
#1 Excessive piston to bore clearance.
#2 Wrong piston.
#3 Excessive wrist pin to piston clearance.
#4 Bad con rod bearing.
#5 Wrong head/base gasket crush.
#6 Too much taken material taken off of head (That's all I can think of now!!)

Or it could be none of these and the piston is hitting the gasket like HondaMechanic said.

 

ive pulled the head and the piston has indentions where the valves line up with the piston, if i didnt put on a thick enough gasket will it cause it

 

Too thin of a gasket COULD cause it. It depends on how much clearance there is in the stock configuration. Did you do anything else besides boring it and putting in a bigger piston? You should use the same thickness gasket but with a bigger ID to match the new bore dia.

 

<div class="FTQUOTE"><begin quote>Originally posted by: juttin_15

ive pulled the head and the piston has indentions where the valves line up with the piston, if i didnt put on a thick enough gasket will it cause it</end quote></div>

those are valve reliefs they are there from the factory.

 

what if i use silicone on each side of the gasket?