oily exhaust port

icontender · Post by **icontender** » Fri Jun 12, 2009 8:48 pm

I was checking over my spare engine when I noticed one of the exhaust ports (#1) was very oily when compared to the others. The other exhaust ports just had carbon buildup. What would cause this oily buildup in the one exhaust port. Also how can I clean all the exhaust ports so they look nice and shiny.

haro504 · Post by **haro504** » Fri Jun 12, 2009 8:57 pm

i would say its either an oil ring on the piston or most likly the valve seal

cad600 · Post by **cad600** » Fri Jun 12, 2009 8:59 pm

Pull the head off and remove the valves is probably the best way to clean it.

As for how it got like that, IDK

. But I'm thinking it is not an easy or cheap problem to fix.

95FZR600 · Post by **95FZR600** » Fri Jun 12, 2009 9:11 pm

Sounds like the rings are the issue.

Post by **sweekster** » Sat Jun 13, 2009 12:30 am

I'd be curious to know the compression numbers on the cylinder

mszilves · Post by **mszilves** » Sat Jun 13, 2009 12:34 am

sweekster wrote:I'd be curious to know the compression numbers on the cylinder

Definitely a good start. I would also add that it is possible to have good compression, and have bad oil-control rings, causing the same oil-burning problem. I had that exact issue on mine last season before I rebuilt it with new rings, and now not a drop of oil is consumed. For the longest time I thought it was coming from the valve guides/seals, but it turned out to be the rings (specifically the oil control rings).

But like it's been said, probably not a cheap or easy fix... sorry man.

modkingfzr600 · Post by **modkingfzr600** » Sat Jun 13, 2009 7:57 am

[quote="icontender"]I was checking over my spare engine when I noticed one of the exhaust ports (#1) was very oily when compared to the others. The other exhaust ports just had carbon buildup. What would cause this oily buildup in the one exhaust port. Also how can I clean all the exhaust ports so they look nice and shiny.

even if you polished the exhaust ports to a sparkling shine, they would be black in less than a few hours of riding. I would just get the "buildup" or the carbon chunks out of the ports for now.

the oil burning is either from worn valve guides, valve seals, or rings.

mossy1200 · Post by **mossy1200** » Sun Jun 14, 2009 5:31 am

If its rings the oil would have burnt away rather than collect in exaust outlet as the only way that rings can get oil there is while bike running unless you stored your spare motor sitting on its front rather than as it sits in bike.
How ever valave guide seals will let oil run down if old and cracked.common in a motor that sat for a while.

gravity says oil goes down unless something pushes it up.
Combustion says oil burns away rather than collect.
Conclusion oil leaked down valve guide seals.

Dont you dare reassemble without the port and polish photos.We expect two full days sanding.

yamaha_george · Post by **yamaha_george** » Sun Jun 14, 2009 7:20 am

mossy1200 wrote:
Dont you dare reassemble without the port and polish photos.We expect two full days sanding.

+5 on the cause,

two days per port surely is what you meant

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