Yamaha XT600E blind plug pops out
 

Hello

I have a Yamaha XT600e 2002 model and the blind plug keeps popping out spilling oil everywhere.

I've spent a small fortune getting the Yamaha dealership to fix the problem with no success. Their "fix" lasts for about a week then the plug pops again.
They've changed the piston rings, piston, valve stems, gaskets and oil pump, oil filter but he problem persists.

On startup the bike billows white smoke then it goes away. Sometimes it smokes, sometimes it doesn't. Generally it does but there is no consistency.
Does anybody have a similar problem?

Blind plug - where is it? What's it plugging? I assume the crankcase as it's spilling oil, which would be a crankcase pressure issue. Is the breather system functioning or is it plugged?

Also, SOUNDS like a coolant leak given white smoke, possibly a cracked head or cylinder leaking coolant into the combustion chamber. This COULD also cause a buildup of pressure in the crankcase. Is there any sign of water in the oil? (white / milky)

I'm surprised a dealer hasn't found the issue after all they've done.

This is 4pt model and its aircooled! Smoke maybe from broken valve seal, maybe damage when installed. Try start when engine is on stand and next time when its raised up straight and see if difference in smoke. Showpict of plug.

Sounds most likely to me, but amazed it hasn't been noticed considering work done.

Presumably blind plug refers to the kickstart plug? No idea how these are held in though...

The blind plug is a rubber plug that sits on top of the crankcase. It pops out when there's too much pressure. The bike is air cooled. When I get it back from the dealership it lasts about 2 weeks then the plug pops again.
It only happens on start up. Never when riding. Generally about 10 seconds after startup but the last time was after I let it idle for about 4 minutes waiting for the smoke to clear. There was no discernible difference in smoke density when idling on stand or upright.
Sorry but I'm not a technical guy. Can you explain what a breather system is and I'll check if its blocked. When I google it looks like an air filter with a hose. I'll check that after work.
Thanks for the feed back.

I have same engine and had others but never had any plug popping, still dont understand where it is explain side front rear? Pict is best. Can it be the breatherhose from engine is plugged? Its in the front left side under starter engine and goes up back to aircleaner box.

Yes. Picture please. Is it number 7 on the picture ??


I have the same bike too. Never had this.

Is the crankcase breather blocked ?

Is the oil level correct ? I would full drain (BOTH drain plugs) and measure oil.

Is the oil strainer clean ??

Has anyone adapted, enlarged the hole in the crank case so the plug doesn't fit well ??

The XT600 has an oil check valve in the RH crank case. It's a ballbearing with a spring. I would be checking this too.

There is definately a blockage or problem in your oil circulation. Have you checked your oil tank is refilling ?

Have you replaced the plug? A new one will likely be a tighter fit, they shrink over time. The XT crankcase ventilation is provided through small holes in the balance shaft inside the engine and then out through the ventilation hose and into airbox . If those holes are blocked then crankcase pressure will pulse badly as piston goes up and down, possibly causing plug to pop out.

Is your engine oil level overfilled or is it wet sumping ie all the oil tank contents draining into engine sump when bike is sitting? if excessive oil is sitting in the sump when starting, then excessive oil mist caused by crank running in oil can be drawn into the intake, causing smoking until the oil levels go back to normal level after a minute of running..ie oil tank is refilled and minimal oil in sump. More often than not a worn oil pump is main cause as will allow oil drainback from the oil tank into the sump when it is sitting.

If it is not wet sumping then i have found that the smoking on start is usually worn or poorly seated piston rings. Did the dealer correctly install new piston/ rings? As the piston and rings warm and expand, the smoke will stop but engine will still usually have excessive oil consumption.

A big single pumps a lot of air through the cases as the piston goes up and down. If your crankcase breather isn't totally unrestricted the cases will experience large pressure peaks.

Why even bother helping people when they dont even take the time to follow up...