I was doing a longer than usual cruise this morning. I did about 150 miles and heading home was doing 65 mph on the highway around 5000 rpm. All of a sudden I loose power and see a lot of smoke coming out of the breather and A LOT of oil all over the place. Smoke coming out the exhaust too. I pull over and the bike is still running but rough. I shut her down and get a tow home. I'm going to have to take the engine out to see what's what but any ideas as to what happened. I don't think there is a hole in the piston because of detonation. My timing was bang on but you never know... Here is a pic of the oil. No unusual noises as of right now too.
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The stains running down the engine look rather thin for just oil. You may have had gasoline thinning out the oil. Take a good smell of the oil in the sump.................does it smell of gasoline? If you smell gasoline, then drain the sump competely and means the carbs need checking to see why they are over flowing raw gas.
Start with the basics.....................compression test.
Start with the basics.....................compression test.
scabber
XS650 Guru
Good observation retired few people even think about cylinder wash by over jeting or a carb leaking.
Thanks for the reply guys. I did a compression test and the left cylinder has 130 and the right has 0. I think there is a hold in the piston from whatever reason. I'll have to replace the piston and clean out the bottom end. Hopefully I won't need a rebore but if there is a lot of damage from parts flying around then the engine is scrap metal.
scabber
XS650 Guru
You should check your advance unit likely the cause of a holed piston, over advanced ignition. Find the cause or it might happen again.
Tomterrific
XS650 Junkie
Were you using premium gas in the tank? I have been on a campaign to get folks to run high octane pump gas in their old bikes for years. Every season I read posts and hear stories from friends and virtually 100% of the holed pistons are running low octane 87 swill. While premium might not save an engine if the mechanical advance blows out, the high octane will certainly slow the destruction compared to low octane swill. But even with no mecahanical failure, conditions can lead to detonation with only 87 octane.
Detonation will commonly show up on the highway and hole a piston when we least expect it. Wind noise and engine clatter will mask the start of the detonation. Detonation will get worse until teh laminar layer of insulating gas over the piston crown is scrubbed away and the super hot combustion gas gets to the aluminum. Detonation gets worse and soon blows a hole through the piston. Don't listen to anyone who says 87 is okay. For 20 cents more, an engine can be saved.
Tom Graham, 45 years of messing with old bikes!
Detonation will commonly show up on the highway and hole a piston when we least expect it. Wind noise and engine clatter will mask the start of the detonation. Detonation will get worse until teh laminar layer of insulating gas over the piston crown is scrubbed away and the super hot combustion gas gets to the aluminum. Detonation gets worse and soon blows a hole through the piston. Don't listen to anyone who says 87 is okay. For 20 cents more, an engine can be saved.
Tom Graham, 45 years of messing with old bikes!
bbillington
blorp a dorp dorp
It's cheap insurance. I do the same with our turbo cars.
OP: pamcopete has a video showing the snap back of the advance unit weights/springs. Note the position when you take the cover off, and test your unit.
Hey TomT.---I would love to put high test in my XS but the age of the fuel makes me nervous because nobody seems to buy it any more---I do use mid-range 89 because it gets sold more and therefore is fresh and not old---Perhaps I will look into some octane booster---
cros36
thread killer
you talking about the age of premium in the tanks at the gas station?
Yes, I feel the premium is old---When I go to the drag strip I buy 5 or 10 gal. of race fuel that is 108 I believe---Usually I cut it with the mid-range 89
cros36
thread killer
i swear im not trying to be argumentative, but how old do you think that 108 is?
I hear ya---At the drag strip they sell it from 55 gal drums and I believe more people buy it to take home with them, than use it at the track---The fact is that oxygenated and ethanol enhanced fuel starts to loose it's umph pretty quickly---Sta-Bil even has a new product to combat the short shelf life fuel---
