Wilsons Sandbox

All, I was wondering if I could get some advice from everyone. My trusty 1989 KLR 650 has been burning a fair amount of oil recently, about 1 qt. every 100 miles or so. Also, when pulling up a hill, I would loose power above 3000 RPM's. I thought it was rings, so I got started and pulled the motor, and took the head apart. Now that I have it apart, I am a bit mystified. Normally when I have had problems with my other bikes burning oil, I find wear marks in the cylinder from the rings, and its pretty obvious I need to do an oversize piston. The cylinder looks and feels clean and smooth, like brand new. Same with the piston, no wear marks or anything. I got to thinking it may be valve seals leaking, but that seemed like a bit much oil to burn through a simple valve seal. Also, the bike would smoke a bit whenever I gunned it. And occassionaly when I started it in the morning, it would puke out a smoke cloud. I have yet to figure out why it only smoked sometimes, oil level inside the engine did not seem to make a difference, nor did the pistion it was parked in. Any thoughts, concerns, or reccomendations would be greatly appreciated. -- Regards, Richard Bessey System Administrator Vivio Technologies

Richard - The only way to conclude anything is by measuring the components. I'm going to assume you haven't bored this engine already. Did you take cylinder pressure tests (limit is 77-124psi) or do cylinder leak-down testing? Oil pressure tests (11-21psi at 4,000 rpm)? These are pre-tear-down, so not that important at this point. But in the future, take these measurement for baseline and interval comparisons. If it's just seals, you'd see this with positive leak- down testing and save a lot of effort. Visually, it's difficult to determine extent of wear (smooth polished cylinder, no cross- hatching, etc.), but only bore gauges, calipers and other tools will provide the exact details. Of course, four leaking valve seals could relieve your machine of a lot of oil but a quart in 100 miles is extreme. It's nearly 1/2 the oil capacity. Anything is possible, however only measurements will dictate the health of the compression ecosystem. I'd inspect and measure the valve seats, cylinder, piston, and rings with appropriate tools/tests and compare with service limits. For the seats, simply replace them. The blue smoke is a dead giveaway in this case. And while you're in there, I'd consider doing a complete valve job seeing it's a 1989. Of course, a qualified shop should be able to provide you the results of doing a complete inspection if you don't or can't do it yourself. A standard valve job including replacing seals should run $200 if you deliver the head. The service manual describes measurements and service limits for cylinder, piston and rings. I started to type/describe them, but it's colossal. I'm simply going to refer you there. My guess is the seals alone will make a big difference, but you're this far and considering the vintage I take the measurements on all compression components. Furthermore, have a look at the balancer ecosysem while you're in there. As part of this inspect/clean the oil screen on the clutch side. This screen clogging, a bad balancer bearing and/or chain slack are silent engine killers. Specifically, check the 3 gears with rubber dampening material for vitality. If they're worn beyond reason, your balancer spring will be (unsafely) slack. Also, measure the chain length as well. Again, follow the service manual (straight forward) or email me. Brian