VintageVmax.com

i have a rebuilt vmax 540 motor and it seams like the pistons are lose in side the motor and it makes noises when u turn it over by hand and it also reads 110 compassion in both cylinders i have brand new pistons and rings in it. what could be wrong with it maybe be a broken ring? i have new o ring and gaskets in it. should it read 150 in both cylinders plus i haven't broke it the motor in yet

Keith, Did you check the cylinders and the ring gap ? See http://www.vintagevmax.com/1986_service.htm "i have a rebuilt vmax 540 motor and it seams like the pistons are lose in side the motor and it makes noises when u turn it over by hand and it also reads 110 compassion in both cylinders"
When you say Seams like this makes me believe (Like everyone else after a rebuild) you are simply nervous. Did you coat the bottom end bearings and cylinders with oil during assembly ?

Some good reading !
http://www.mototuneusa.com/break_in_secrets.htm

Make sure the engine has been warmed up before beginning the test, to ensure that the oil has been warmed up. A cold engine will not test correctly.
Disable the ignition module or coil.
Insert the compression tester into one cylinder spark plug hole at a time.
Hold the throttle to full open position to ensure the engine gets adequate air intake.
Crank the engine continually for at least five to 10 full revolutions to obtain an accurate reading on the compression tester.
Record the reading for each cylinder. If any of them vary 10 percent or more from each other a problem may exist in one or more cylinders. If the variance is greater than 10 percent, specialized testing equipment may be required to fully diagnose the problem.
If all cylinder readings are within 10 percent of each other, no further testing is required and compression is considered optimal.

Vmax540 wrote:Keith, Did you check the cylinders and the ring gap ? See http://www.vintagevmax.com/1986_service.htm "i have a rebuilt vmax 540 motor and it seams like the pistons are lose in side the motor and it makes noises when u turn it over by hand and it also reads 110 compassion in both cylinders"
When you say Seams like this makes me believe (Like everyone else after a rebuild) you are simply nervous. Did you coat the bottom end bearings and cylinders with oil during assembly ?

Some good reading !
http://www.mototuneusa.com/break_in_secrets.htm

Make sure the engine has been warmed up before beginning the test, to ensure that the oil has been warmed up. A cold engine will not test correctly.
Disable the ignition module or coil.
Insert the compression tester into one cylinder spark plug hole at a time.
Hold the throttle to full open position to ensure the engine gets adequate air intake.
Crank the engine continually for at least five to 10 full revolutions to obtain an accurate reading on the compression tester.
Record the reading for each cylinder. If any of them vary 10 percent or more from each other a problem may exist in one or more cylinders. If the variance is greater than 10 percent, specialized testing equipment may be required to fully diagnose the problem.
If all cylinder readings are within 10 percent of each other, no further testing is required and compression is considered optimal.

i had the motor done like last year i havnt been able to ride or idal it because of problams i went from no spark than that was fixs then the carbs filling up the motor with gas so i took the carbs apart clean tham but now for some reasson the air boxs is leaking gas ???

MY VMAX HAS 140 psi. 3:16 (yammie tony))

What kind of pistons, forged or cast?

Bob Vehring wrote:What kind of pistons, forged or cast?

i dont know what my dad put in it but i do know that its not the chrome cylinders i just had it running but i dont no why its leaking gas from the air box?

With cast iron liners the walls wear, you bore or hone to get the hole straight then finish hone to the size of the pistons, Cast pistons can be run tighter then forged. Forged also need to get some heat in them to get round. In other words let it warm up each time before you run it hard especially with forged pistons. If the clearance is more then .005, the pistons maybe rocking in the bores. That could be the sound you hear.

No idea why there is gas in the air box, shouldn't be except for what sprays back from the carbs. Clean it out and see if more gas gets in there.