How to compression test

[wally]

I managed to get hold of a compression testing kit.

I would like to do a quick test on the second bike to gauge the condition of the motor before I start. I checked the booklet and it states you have to warm up the motor to operating temps before you test.

Now for my issues...

1) All the wiring has been removed.
I have it, but in boxes and I reaaaallllly don't feel like putting it all back in just to do the check. To get the carbs dialed in, etc, etc...

2) Motor stood for about a year. We squirted some oil down the cylinders a few months ago to see if we can crank it over and it cranked easily (by jumping from the car to the starter). Don't really want to spend bucks on oil and consumables for a quick test.

How reliable will the reading be on cold swings? Or am I stuffed...

Also don't want to open the motor unless I really have to, as gasket sets from Suzuki are near impossible to find locally.

Thanx!

 

[spyug]

You will get some readings but they won't be accurate so you might want to wait until its all back together again. If the engine is cold there will be no expansion of rings and as such likely leaks will be present and readings will be low. Adding oil will bring readings up but they aren't going to be true so its a worthless endeavour IMHO.

Good luck with the project,
spyug

 

[wally]

mmmmm...

I don't want to venture into months of body work and related expenses and only then to ding out the motor is completely stuffed.

Quite a predicament...

thanx!

 

[hampshirehog]

A cold test will give you an idea of where things are and it is worth doing for peace of mind. Just bump the starter motor directly off a battery if you don't have the bike wired up - use heavy duty leads as it zaps quite a bit of current.

If the test shows higher than the lower limit listed in the manual and both cylinders to be fairly close you'll be fine. If the test doesn't show those figures you then have to choose between leaving it until you can run it or doing a precautionary strip down. I would be minded to leave it but it's obviously your call.

 

[wally]

Thanx. Essentially the starter motor is the only electrical part on the bike (apart from the motor). We jumped it like that from the car a few moths ago.

 

[2BRacing]

Hi Wally

If the engine has not run for a year, the rings may be a bit gummed up, so resulting in false readings. Maybe this is going to lead you to incorrect diagnosis, so I would view the test results bearing this in mind.

Good luck!

Ben

 

[koolaid_kid]

You also must have the throttle wide open when you run the tests.