I have a 2001 400ex stock engine. Im gonna buy a compression tester and see what the compression is on the engine since i think its burning oil and the rings are going on it. What should the compression be between for a good engine?

 

monster,

do you plan on doing the work yourself? If not, have the place you are going to have rebuild it do a quick compression test for you. It takes them about as long to do a compression test as replacing a spark plug. The other alternative is take a plug with you to an autopart store that allows you to borrow tools. If you get your own, test it first for a baseline reading and then put a tablespoon of heavy oil in it. Test again. If your reading goes up, then you need new rings. If not, it could be your vavles. If you do buy your own tester, get a reading after you do the rebuild. This way, you have a new baseline reading for future comparisons.

The reading should be between 120-128 for a stock 400ex.

/Jon

 

yea thanks. Im training to be a auto tech in school so im pretty good with these things. Im going to buy one anyway, its good to have around the shop. Thanks for the advice.

 

The 2001 went through a similar problem not to long ago. It smoked whitish colored smoke under acceleration through all the gears. It made me sick anytime I had to follow this quad. We were in a freakin cold spell so I decided to let Dirt First in Baltimore do the work. They checked mine over and performed the following work:


Rings $40.00
Top end gasket kit $40.00
cam chain 90.00
spark plug 2.50
2 intake valves 50.00
valve cover bolt 8.00


In-house Labor 200.00


Headwork (outside labor) 100.00

Total $530.50

/Jon

 

ah yea. Yea im thinking about boring it out so if anything i will let my friends shop do it. Thanks for the tips.