VtamRLN
03-19-2014, 11:13 PM
I found a '84 YTM225DX that barely ran. Smoked bad and had piston slap like a marble in a tin can. Pulled the head, jug, and piston. Ring end gap was over .125 and piston rattled around in the bore.
Took it to a small engine specialist, he bored the jug, got a new piston for it. rings and gaskets. Put it back together, it ran for maybe 10 mins. Wouldn't restart. Time goes by and I am back on the project after a couple of years.
Nothing a new choke cable, carb cleanout, etc.... shouldn't fix. It has been over a week and it just won't run. Back to square one. Reset the valve lash, cleaned carb, fresh fuel, etc.... I am feeling very little suction with my hand over the carb. Ran a compression check. Cylinder checks at 105 cranking compression. Reset valve lash, 105 cranking compression. Verified cam timing. Disconnected exhaust, 105 cranking compression.
Removed carb, 105 cranking compression.
Pulled the head and it a Hemi style chamber that is almost .625 deep. Liquid checked the valve seats with racing gas. Zero leakage on I /E. Engine is rated for 8.5 to 1 compression. Piston is a flat top with Intake / Exhaust notches in piston. I don't see how this setup can get to 8.5 to 1.
So, Does anyone know the cranking compression should be for this setup? I am thinking 130-140 psi. If you can't build enough pressure, you are sure not going to create enough vacuum to pull fuel from the carb.
I am open to any other ideas as well.
Thanks in advance for your assistance.
Took it to a small engine specialist, he bored the jug, got a new piston for it. rings and gaskets. Put it back together, it ran for maybe 10 mins. Wouldn't restart. Time goes by and I am back on the project after a couple of years.
Nothing a new choke cable, carb cleanout, etc.... shouldn't fix. It has been over a week and it just won't run. Back to square one. Reset the valve lash, cleaned carb, fresh fuel, etc.... I am feeling very little suction with my hand over the carb. Ran a compression check. Cylinder checks at 105 cranking compression. Reset valve lash, 105 cranking compression. Verified cam timing. Disconnected exhaust, 105 cranking compression.
Removed carb, 105 cranking compression.
Pulled the head and it a Hemi style chamber that is almost .625 deep. Liquid checked the valve seats with racing gas. Zero leakage on I /E. Engine is rated for 8.5 to 1 compression. Piston is a flat top with Intake / Exhaust notches in piston. I don't see how this setup can get to 8.5 to 1.
So, Does anyone know the cranking compression should be for this setup? I am thinking 130-140 psi. If you can't build enough pressure, you are sure not going to create enough vacuum to pull fuel from the carb.
I am open to any other ideas as well.
Thanks in advance for your assistance.