Author Topic: poor mans leak down tester  (Read 5815 times)

0 Members and 1 Guest are viewing this topic.

Offline BDI

  • Hero Member
  • *****
  • Posts: 1,533
poor mans leak down tester
« on: June 10, 2008, 12:05:24 PM »
These are rubber expantion plugs that you use to plug the exhaust and intake. These can be hard to find but if you have a pep boys near by they have them, or a plumbing house should have them also. The second picture is of my compression tester with the gauge removed and a schrader valve screwed in it's place. For this to work you have to take the schrader valve out of the end of the compression testers whip that screws in to the spark plug hole or you can't put air in the engine.  Use a small foot pump for a bicycle or something similar to put six psi in the engine, do not over pressure the engine. If the plugs come out things can get busted that includes your face make sure the exhaust and intake are clean and dry of oil and put the carb clamp on the rubber boot and tighten it just like the carb was in place then tighten the plug. The engine should hold six psi for sixty minutes. If it does not then use soapy water in a spray bottle to look for leaks. To check main seal put soapy water on the crank case breather tube if it blows bubbles the right side crank seal is leaking. To check the left seal you have to remove the mag and spray soapy water on the seal. If the left seal is leaking it may be obvious, do to, gas and oil behind the mag.
« Last Edit: June 10, 2008, 12:41:27 PM by BDI »
Smoke every cigarette like It's your last and ride like you stole something!!!

Offline KXcam22

  • Hero Member
  • *****
  • Posts: 1,677
Re: poor mans leak down tester
« Reply #1 on: June 11, 2008, 03:22:38 AM »
BDI,
  Excellent writeup!!  Question: is a round plug good enough to seal the intake (not a reed shaped plate) or does the plug go in the round part where the carb spigot would insert?  Thanks. Cam.

Offline hughes

  • Hero Member
  • *****
  • Posts: 1,923
    • Dirt Hammers
Re: poor mans leak down tester
« Reply #2 on: June 11, 2008, 04:29:09 AM »
The piston would also need to be at the bottom of it's stroke to ensure the ports are open.
Open Class 2-Stroke Kawasaki KX500
Yamaha 2005 YZ250
Richard Hughes
Dirt Hammers - Online Off-Road Journal
hughes@dirthammers.com
http://www.dirthammers.com

Offline BDI

  • Hero Member
  • *****
  • Posts: 1,533
Re: poor mans leak down tester
« Reply #3 on: June 11, 2008, 09:58:20 AM »
BDI,
  Excellent writeup!!  Question: is a round plug good enough to seal the intake (not a reed shaped plate) or does the plug go in the round part where the carb spigot would insert?  Thanks. Cam.

   Yes use the round plug in the intake boot so you can check the rubber boot and reed block gaskets for air leaks also. Leave no stone unturned, I have even found cracks in cases before that you could not see with the naked eye.
« Last Edit: June 11, 2008, 02:17:04 PM by BDI »
Smoke every cigarette like It's your last and ride like you stole something!!!

Offline wreck-n-roll rik

  • Full Member
  • ***
  • Posts: 51
Re: poor mans leak down tester
« Reply #4 on: August 30, 2008, 03:43:17 PM »
Great idea - will work on just about any engine as long as you have plugs -thnxs

Offline bob larry

  • Full Member
  • ***
  • Posts: 150
Re: poor mans leak down tester
« Reply #5 on: April 20, 2010, 02:05:33 AM »
Glad I saw this I almost put 100 psi from my comp. through the engine............

Going to build one......other site said you have to plug the power valve vent too....?

2001 KX500