leak down test help

argclh6670 · Post by **argclh6670** » 03:03 pm Jul 21 2015

Hey people, i have a 95 rmx250 that im doing a complete rebuild on.....bottom and top, replate the whole nine yards. Motor on bench, cylinder installed and tryn to do a leak test on it and i cant get it to hold any pressure. Ive sprayed everywhere with simple green, on tester, cyl, head, reed block, exhaust. Cannot find any leaks. I just built tester a few months ago, worked great on sons kdx 200...i confirmed tester was working fine today. Wonder if im doing the test wrong??

Post by **bufftester** » 03:47 pm Jul 21 2015

I also have a 95 RMX. I assume you have blocked the exhaust and intake ports and have the gauge installed in the sparkplug hole? The RMX exhaust valve arrangement is different from the KDX. Most importantly, the resonator is ported to atmosphere on the left side of the motor. You will see a large (fuel line size) hose that exist the cylinder on the left side just below the head and is vented down under the motor. You will need to block that port or you'll never build pressure. On a different note, I am having starting issues on my RMX. Starts after a couple kicks cold, runs a few seconds and dies. Won't start after that. Pull the plug and it's wet. Dry it off, kick the bike over a few times, put it in and it fires for a few seconds and the same thing...over and over...very frustrated with it right now.

argclh6670 · Post by **argclh6670** » 04:10 pm Jul 21 2015

bufftester wrote:I also have a 95 RMX. I assume you have blocked the exhaust and intake ports and have the gauge installed in the sparkplug hole? The RMX exhaust valve arrangement is different from the KDX. Most importantly, the resonator is ported to atmosphere on the left side of the motor. You will see a large (fuel line size) hose that exist the cylinder on the left side just below the head and is vented down under the motor. You will need to block that port or you'll never build pressure. On a different note, I am having starting issues on my RMX. Starts after a couple kicks cold, runs a few seconds and dies. Won't start after that. Pull the plug and it's wet. Dry it off, kick the bike over a few times, put it in and it fires for a few seconds and the same thing...over and over...very frustrated with it right now.

i was just thinking bout that port. No, not attached at sparkplug hole....at the reed block, is that wrong? As far as your issue, mines always been fairly cooperative in starting n staying running. Lol....but, youre obviously getting fuel....maybe an electrical issue?

Adamnb1 · Post by **Adamnb1** » 11:04 am Jul 22 2015

sounds like Buff had the answer to your questions.
I don't think there is a problem with going in through the intake vs plug hole. I think some will say to make sure your piston is at bdc so your transfer port is available, but given a small amount of time I think the air would get past the rings and pressurize the top end anyway. Actually, pressurizing from the intake with piston at BDC requires that to happen anyway since the piston is in way of intake port, the air will need to squeeze past rings.

Bdub200 · Post by **Bdub200** » 06:53 pm Jul 22 2015

Hey Bufftester, I agree on the electrical, but I'm guessing you knew that. I had kind of a simular issue once and it was pick up wires on the old xs 1100's that had an open- you could feel the open in the wire. Bottom line after testing the basics like coil (maybe check for spark as you kick it over) the issue could be heat or vibration related and connectors or wires.

KDXRIDER.NET

KDXRIDER.NET