Is it possible that if you never adjust valves the engine could lose a lot of compression? 1990 Suzuki VX800, 19,000 miles on the clock. No idea if it has ever had the valves adjusted, only got it 3,000 miles and 6 months ago. It is now not running and after a compression test, has 90 psi in the rear and 150 psi in the front cylinder. Don't really have the time yet for a leak down test. Could the exhaust valves be the cause of the low compression? thanks.
Yeah, valves should be adjusted from time to time, both intake and exhaust, they are the two biggest areas of the compression system that would cause low compression. That old of bike probably needs a good 'go-thru' to see what's happening, the leak-down is your best bet at that happening.
Yes it can lose compression if your valve lash is too tight. This can also cause the valves to burn. Adjust your valves as soon as you can.
