Compression Test Techno v Evo

[cello]

Just airing this to see what you think , ran a Compression Test on my Techno 97 and got nigh on 170 PSI , whan I had the exhaust off I took a look at the piston and it looked worn and scored but this bike seems to have a lot of compression whn kicking it over and seems to pull very very well low down.

 

Tried a 2014 Evo 250 and only go 110 PSI well it was more like 106 but I rounded up, is this right?

 

I know it all depends on the life that the engine has had but I would have expected it to be the other way round with more compression from the Evo, the Evo does sound a little slappy like th little end is starting to knock so its goinf to have the head off for inspection at some point..

 

I must say the Evo controls all work perfectly compared to the Techno , brakes particulary but I guess if the Evo motor is good it should pull hard in all gears even the high rato 4 and 5 but its difficult to test round where I live as the bike is not road legal. Is there any road test I could do to test the motor out as I dont want to DNF because of the motor notfiring up or not pulling up a hill in a wet soggy trial New Years trial I'm thinkin of entering.

 

TIA

[konrad]

A lot of factors go into making an accurate compression test.  A few things to think about: 

Compression must be tested with the throttle held wide open.

I usually keep kicking until the gauge stop rising. This can often be a dozen kicks.

The spark plug adapter you use can make a big difference if it increases the combustion chamber volume appreciably.  For example, using a short-reach adapter in a long reach plug hole gives inaccurate (low) readings. 

If the piston crown and/or combustion chamber has a large about of carbon buildup, this will increase the reading. 

Smaller cylinders tend to have higher cranking pressure than larger ones. 

The barometric pressure (altitude) will affect the exact number.

A hot motor will make more cranking pressure than a cold motor.

Oily cylinders tend to make more pressure than dry ones due to a better ring seal.

There are other factors too.