Checking compression

 If understand this correctly, checking compression will tell me if I
need new rings. (I've 10,000 miles on my Yamaha Zuma scooter so I may
need them).   How is this checking done.  Do you take off the spark
plug and screw in some device. Can a regular garage mechanic do it or
do I need to go to a motorcycle mechanic?  Thanks.

 Kent Murdick wrote:

Don't know about the history of that particular machine, but 10K needing
rings would be unusual.
What leads you in that direction?

It is basically a pressure gauge that screws into the spark plug hole.
A "regular" mechanic could do it IF he has the right adapter but probably
wouldn't know if the reading obtained was good or bad.

Also note that a valve seat leak down test is usually done first.....as
BADLY damaged valves makes a compression test impossible.  The other side of
that coin is that BADLY worn rings makes a valve test difficult too.

Best take it to a Yamaha dealer to sort out whatever the problem IS because
it may have nothing at all to do with rings OR valves.

 
The Yahmaha dealer will just say he found nothing wrong and charge me
$100.

 
Then there probably is nothing wrong and you can thank your lucky star that
he didn't sell you an expensive top end job like some dishonest shops might
do.

Modern bikes and scooters are very unlikely to need major engine work at
10,000 miles.  I've seen Harleys and BMWs with over 100,000 that we couldn't
even measure the wear on. I'm sure nearly all brands are the same.

Remember, no bike or car is ever as fast as it was when you first rode it.

 

Eh? Mine is a LOT faster now that the mileage has increased.


--
Beav

VN 750
Zed 1000
OMF# 19