ok just worked my 97 banshee with many motor mods including coold head rebuilt crank with blaster wiseco pistons 28 pwk carbs reed spacers aluminum intake manifolds with no cross over tude. and it was ported. Work was done by ohton racing

I was breaking it in after finally getting it to run because of ther jets and carb settings. I ran if for 1 min then let it cool
then 2 min and cool
then 5 then cool
then 15
then i took it for a 3 min ride 1/4 throttle
come up the next day start it
go for a 5 min ride. shut it off where it was and then try to start it
wouldnt start so it was towed home
checked the whole wiring harness, statot, coil, cdi, and removed tors
has tons of spark
cool head has 17 domes lots of compression
brought it home and it wouldnt start. notices that compression was blowing back threw the carbs
!!!
i put my hand over the card flange and it would push my hand off
pulled jug
noticed it was only whereing on the intake and exhaust walls
not the left and right
crank has a puddle of gas in bottom.

Why would the compresion blow out intake ???
bad porting ?? reeds ?? carbs???
any ideas
should that wear like the because i didnt have it how enugh to expand and cove whole cylender ???
i am taking pics of the jug tomorrow so i can post them and show how the sides still look like the cross hatch and the front and back are smooth

this is only happening on left cylnder not right one.

thanx for the help

 

If its blowing back by the carbs I can almost gurantee its the reeds, probally broke one or something...

 

The intake and exh side of a cylinder tend to wear more than the transfer side of the cylinder. The piston skirt, which is on the int and exh sides, have more surface area, more surface area ='s more wear.

Sounds like you broke a reed...