Q: I’m riding around on, and have done since I bought it new, a 2005 Yamaha XT660. But over the past few months it seems to be losing power, and therefore a little sluggish, which is becoming annoying.
Therefore I would like to check the compression, but seeing as I live on a farm 160km north of Gaborone in Botswana, it’s a bit difficult.
So is there any way I can check the compression, which you might know of, without using a proper compression tester?
Your advice will be greatly appreciated, Noddy.
Keith Collingswood Botswana
A: You will have to find a proper compression/leak down tester to do the job properly, because it will show the ‘blow-by’ percentage loss, if any, through the inlet and exhaust valves and the piston rings.
But for a quick ‘farm test’ you could put an airline from a compressor into the spark plug hole, once removed. If you get a good seal and the piston must be at T.D.C. (top dead center), you could possibly listen for air coming from the air-box (inlet valve), or from the end of the exhaust (exhaust valve), and remove the oil filler plug and then listen to air coming from the crankcases (piston rings).
This is only a rough guideline, but if you have severe damage in any of these three areas it will tell you where the problem lies.
Definitely worth a try before you endure a long drive though…
