Testing the health of a motor

1 reply to this topic
  • AFelix

Posted October 06, 2014 - 03:40 PM


What is the best way to test the health of a motor without dissasmbly? Is a compression check valid with hot cams?



Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • grayracer513

Posted October 07, 2014 - 06:36 AM


Conventional compression tests are pretty useless even with no auto decompression.  If a YZ400 is really healthy, you can't really kick it through compression in the first place, and there are no standards published for what it should have.  Even in car engines, the best use of compression testing is to locate one or more cylinders that are lower than the others, not what pressure is ultimately run up.


The best test is a Leak Down Test.  Most shops can do one inexpensively if you show up with the tank off already, and the cool thing is that you can not only see if it leaks too much, you can tell from where.

Related Content


Snake pit oct 30th by The Anvil

Dirt Bike   Dirt Bike Regional Discussion   California
  • Hot  293 replies

Chubby dad, looking at bikes , First trip to the orange/black forum ! by Slow_ride

Dirt Bike   Make / Model Specific   KTM   250-530 EXC/MXC/SXC/XC-W/XCR-W (4-Strokes)
  • Hot  28 replies

2016 YZ450 by CaptainKnobby

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  59 replies

James Stewart back on a YZ450F by YamaLink

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  47 replies

Thinking about Yamaha 250... by Arctic Pride

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  491 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.