Quote:
Originally Posted by bluechip
hi guys,
thanks for all the interest and technical insight.
i looked into it as far as the dealer, i know his rep is impeccable. so i new the compression numbers where accurate. he says the yam 150 and many other 4 stroke compression numbers are that high.
they also do a leak down test which is a static test and the motor is tight (did not get the specific percentage of leakage). the only other point is that the compression test is done at cranking speed, so i am not sure if Adriatic (sp) heating is causing the higher compression at that rpm
thanks Lloyd that is what i was hoping for: 40 top, 5 mpg at cruise
thanks to all
mark
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The leak down test is "King" as far as a more accurate test, When you get your motor get a good leak down tester (around $100 for a good one) and record the base % loss and check it every few months or seasons. When you start to see a slack cylinder or get a loss of 10% more than the recorded base numbers you wrote down when you got the motor you know to look for an issue then before it becomes a failure. Works great on 2 strokes to determine when to re-ring the pistons but can help determine problems on the 4 strokes too.