1986 Honda 200 overheating, oil bubbling, missing oil separator plate

[Luke G]

I bought this project. Honda 200sx. Motor was out of it and shifter was stuck. Seller said it ran before the shifter got stuck.

I took the right side crankcase off and checked the clutches and shift linkage. Everything looked good, except the oil separator plate was/is missing (probably not a big deal I thought at the time). I put it all back together and did a refresh on the top end. 145lbs compression. New plug, new oil, carb refresh. Motor back on the bike and it starts right up. Tons of white smoke, and a heavy vibration. I thought I was getting oil around the rings, so I took the cylinder off and piston and cylinder wall are perfect. The rings were new when I rebuilt the top end. Put it back together, re-jetted to get more fuel, and fixed a hole in the exhaust. Same problem, slightly less white smoke. Also, there is oil leaking out the exhaust when I start it up.

I know that oil separator plate (part number: 15711HB3000) is missing/not on the bike. Is that my problem?

When I check the oil and bike is cold, the oil looks new (and is not over filled). When I check the oil after starting it the oil has tons of little bubbles floating on the top.

Breather tube is clear/not blocked. Carb is clean.

[Dirtcrasher]

It's not that plate, but that plate also guides your oil pump drive chain. It's more than likely the same as the 86/87 200X and should be installed.

You probably remember or have read about how to test rings? Pour some oil in the plug hole and retest compression, if it increases, the air/fuel mix is getting past your rings. Are they installed correctly, with the right ring gap? Sometimes rings are a size too small in this day and age.

Does a fresh top end mean it was measured in a few places, honed or bored if out of spec, and a Honda/Wiseco/Arias piston and ring set installed?? Or is this a turd just slapped a piston in with Amazon parts (no offense intended at all, but it's near impossible to help without knowing every aspect).

It's a 4 stroke, no oil should be coming out of the exhaust whatsoever, could be blow by or leaking valve seals. Bubbles sound like you are compressing the crankcase below the rings. When it runs is there a pulse out the breather tube?

And that thing shouldn't vibrate at all, it has no counter weight. Are all the motor mounts in place and the bolts tight? You definitely have some engine issues.

[Luke G]

That plate is getting hard to find. I found 1 on-line in the EU. What does it do? Mechanically keep the oil pump drive chain from jumping off the sprocket?

Rings were new and to spec. Cylinder was honed and measured in 3 locations, both profiles. The piston was re-used because it was also to spec.

I did disconnect the breather tube from the frame yesterday to confirm that it was not blocked and did not have oil in it. I didn't check if it was pulsing. I'll do that today.

I went back and checked my notes on this bike and I did not change the valve seals. I'm thinking I should pull the head off and replace those.

[Shep1970]

Ya "someone" bought a bunch of those plates a few years ago....for cheap. Damn hoarders
Yes u need that plate- same plate as 86/87 200x as steve said.


shep