Box Stock

gx200 clone clicking noise

J

jrdragbike

New member
hello im new here,
but here is my problem i have a highly built clone and for some reaason there is a popping noise coming from the head or the block, it only happens when the piston is almost at TDC (top dead center) i can feel it in the exhaust valve. i have tried every other fourm and no one has been able to help so hopefully you guys can ;)
mods are
billet rod +20
flattop piston
billet flywheel
356 lift cam
big valve head 32/28 milled 0.30 14cc
28mm flatslide mikuni
stock rockers
dual springs 36lb
there is prolly more i am just forgetting
 
Are you sure the piston isnt hitting the head or valves with the .020"+ rod you have in it? Im thinking either rod/crank journal has too much clearance or you have piston contacting the head or valves
 
I would suspect the stock rockers. Without knowing about the push rods or guide plate the pivot slot may not be enough for the lift. Rocker stud height in conjunction with rocker position during lift can cause clearance problems Stock lifters will bend/spread in the middle with that build. You need Champion,
Burris, or Raceng rockers. Rocker position during lift can influence performance.
 
Take a look at where the magnet on the flywheel is at when the click happens. We had one we could hear click while profiling the cam near TDC and after a very long and extensive witch hunt, the crankshaft was cracked and when the magnet would get close to the coil, you would hear it click. Engine started and ran and even made pulls on the dyno with the noise but was seconds away from
disaster. Good Luck!
 
there is a popping noise coming from the head or the block, it only happens when the piston is almost at TDC (top dead center) i can feel it in the exhaust valve.

I have a feeling the valve is hitting the piston. use silly putty to check this which will intale removing the head and place the putty on the piston and installing the head with at least 2 bolts, no gasket and with the rockers adjusted to the proper clearence. turn the engine over by hand ans then remove the putty and check the thickness, it will have to be at least .050
 
If your going to check for piston to head clearance or piston to valve clearance, it needs to be done right, with the head gasket, all 4 headbolts, and torqued to spec. Leaving 2 of the head bolts out and head gasket off is not going to give you an accurate measurement. I use .025" minimum clearance between piston and the head/valves
 
Just found this and it appears I have same problem. My gx200 sounds ok until if exchange the standard cam for a 252-0611 from nr racing (not new). On investigation it appears the compression relief mechanism has to much lateral play and catches cam followers. Do I repress retaining pivot or grind follower smaller ?
 
You must log in or register to reply here.
Back
Top