What's up with this

Xs7501978

Active Member
So I was wondering why my bike shoots out white exhaust sometimes...
Here's a video if anyone wants to see.
https://youtu.be/1UwlcNS6eHo
 
Thats leaking intake valve guides. If it shoots plumes of smoke on deceleration/engine brake its piston rings. You need new seals. Has it been standing a long time?
 
Well the guy before me bought it after it had sat for years... But he "rebuilt" it over the winter and then it sat maybe 1 month while I worked on it this summer. Are seals a cheap buy and easy fix or will this be a big project?
Also is it okay to drive it with this leak?
 
Yea you can drive it no problem, until the plugs foul or the oil mix gets so bad it wont fire. I bought a 77 xs750 that smoked, not as bad as this though, but a few thousand kms ad a few oil changes later and it was completely cured with great compression. Is this first time your starting it after you got it, or have you been running it a few miles? Just to rule out condensation or oil sitting in the barrels.
 
Seals are cheap but head has to come off, unless you can lock the valves with compressed air, then you can switch them without disturbing the head gasket. Which would be preferrable..
 
No I've been driving it. It rarely smokes and normally just for a second or 2, like at a stoplight. The video was the worst it smoked and I restarted it and it was not smoking. I've been riding it like I stole it and it runs fine.
 
Xs7501978 said:
Hey dataDavid. It now only smokes when I have the bike choked...
At which temperature :) dont forget that warm air can soon as smoke at certain temperatures...smoke is heavier...when you stop the bike while smoking youll see the difference.

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It smokes when cold and running on the choke? Might just be normal condensation. If it smokes when hot and choked it just means its running rich.
 
It always smokes whether cold or hot. The moment I turn it off it stops smoking...


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datadavid said:
Thats leaking intake valve guides. If it shoots plumes of smoke on deceleration/engine brake its piston rings. You need new seals. Has it been standing a long time?

Other way around. Closed throttle on decel causes higher vacuum in the intake and so it sucks in air from the head, past the seals. On acceleration, high pressures in the cylinder usually presses the rings outward and scrapes the oil off of the cylinder walls. When the rings begin to fail, there is less pressure (or bigger gaps) to perform the oil scraping and it seeps up into the combustion chamber.

I would pull the plugs and inspect them.

If it looks like this, then you're definitely burning oil and need to figure it out. It's only a matter of time before an oil leak becomes a bigger problem.

130_0703_06_z%2Breading_spark_plugs%2Brich_spark_plug.jpg
 
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