Hey guy's.. Ive posted this on another site but i figured maybe someone here will have a definitive direction for me to go or experience with this happening.

I got a 2003 Vinson 500 for cheap because it burned oil. Like white plumes of smoke and at idle it burns all the oil up in the case within minutes.

The compression was at 110# and all of the valves were with in spec for lash.

So i figured i'd rip it apart and put in new valve seals and new rings. Cylinder looks great and I have 130# compression as it sits. The rebuild went great and i followed the service manual to a T

So i have the exact same issue prior to the rebuild, billows white/blue smoke and burns up all of the oil in the crank case fast. I never let it run dry but it burns it up fast.

Anyone have any ideas as to what i missed? and why it still burns all the oil up? Is there a pump or seal im missing?

All oem parts and oem gaskets were used.

Any help would be great, i have no problem ripping it apart again to verify anything.

I just pulled the valve cover and theres a ton of oil in where the valves are. So oil is getting up past the seals from what i can tell.

Coolant isnt milky.

I have done a bunch of 4 and 2 stroke top end rebuilds, this one just has me at a lost is all.

If i crank it over with the valve cover off oil just pours up from this hole. I get it is supposed to get some lubrication to the cam. The amount that comes up is insane and is dumping down directly into the exhaust valves from what it looks like.

 

Even if the valve guides were worn,the new seals should have stopped any oil from seeping into the engine from that area. Question is did you just install new rings on the old piston? If so that could explain why there was only a 20 psi jump on compression from 110 to 130. New rings on a worn piston usually won't seal properly and you can still have oil blow by on the rings because of piston slack. Looking at the parts break down no over size pistons are offered so I guess the cylinder is plated. If so a new piston and ring kit might solve the problem,but if you have the manual I'd check piston to cylinder tolerances which are usually pretty tight on a four stroke along with checking the dimensions of the cylinder itself at the bottom,middle and top. Might be time to have the cylinder replated if beyond the maximum wear limits in the manual.

 

There are no sidewall scuff marks and no signs or indicators of being worn. Ive done a bit of 4 and 2 stroke top end rebuilds and havent had many issues with reusing pistons if they look alright.

I'll bring it in to a local shop and have them mic everything i guess.

It just smokes so much i keep thinking the oil is getting in somewhere it shouldnt.

The exhaust leaks raw oil at the block where it bolts onto it. I have no idea how so much oil can get up there to burn 2+ quarts in a matter of minutes.

The stock compression is 142# so im down 12# which i know once rings seat etc can recoupe the lost lb's.

I'll bring in the cylinder and have it checked out.

Anyone else have any input im all ears.

Thanks OPT..

 

If the valve seals are good, shouldn't let any oil into combustion chamber. Excess oil runs back to sump.

 

There should be lots of oil coming up onto the cam, like hydrex wrote, the valve seals will keep it out of the inlet & exhaust ports.

The engine breather works hard on a single cylinder engine, remove the pipe from it to check what is happening, most quads simply blow a cylinders worth of air out as the piston goes down, and suck the same volume in as it goes up. Another possibility is a cracked head or cylinder, or a blown head gasket, leaking oil from an oil gallery or the head into a port or the cylinder.

 

Valve seals are new the old ones were brittle, i thought that is what was allowing the oil into the cylinder. The head gasket is new so it is making me believe that theres a fracture or crack somewhere. I have to run south for a couple hours today then i'm going to rip it back down.

May go get what i need for a leak down test today too prior to ripping it apart again. I need a leak down tester anyways.

As always guys the advice and knowledge is appreciated. I've done a ton of top ends etc and this one just has me at a loss..

 

Get a leak down tester end of the week.

Going to set this aside for now n start something else. I'll post back when i get some numbers to work with.

thanks for now guys!

 

Leak down test indicated %20 through the rings/cylinder.

Its making me wonder if there actually is an issue with oil getting through somewhere besides the ring. I know %20 is a lot but is it enough to have that much blow by while running?

I have a good suzuki 500 motor sitting in back of the shop. May swap cylinders and pistons and see if it clears it up.

 

Swapped complete topends from a known good Suzuki 500 motor that i've been saving for a sand rail project.

Adjusted valve lash at tdc and Compression is at 140#.

I get the exact same results, ton of smoke and oil pouring from the exhaust manifold while running. I disconnected the spark plug and removed the exhaust and cranked it over.

Here's a video of it running and at the end is the oil and gas dripping from the exhaust manifold while cranking. I'm thinking oil pressure regulator or a blocked passage in the oil system.

Let me know what you think because im at a loss..

 

If you changed out the cylinder and piston and reused the original head,that might be the problem area. Head may be cracked leaking oil into the combustion chamber. Magnafluxing could probably find it or try another used head.