Blowby causing excessive oil pressure?

Lets hit the important info: 81 XJ650 Maxim, 35,xxx miles. I recently noticed that boss for the tach cable was leaking oil at a fairly decent rate. So I bought the seal and o-ring from Chacal and installed them. Suddenly, my valve cover was leaking oil. I checked the bolts and realized they could be snugged up a bit. And just like that, my head gasket suddenly started leaking oil. So I started to think about what could be causing all this extra oil pressure and remembered earlier this summer that there was what looked like exhaust coming out the crankcase vent. I did a compression test and got two cylinders (2 and 4) well below 100 psi, but then realized you're supposed to have the throttle open so they might not be that bad, but there was still a 40 psi difference between the worst and best cylinder. I will redo the compression test at some point, but am leaning towards and engine that needs to be rebuilt. I looked into how much it would cost to drop in some oversized pistons and realized that isn't an option. $1200 minimum (And I highly doubt it would cost that little) in parts for a bike that'll probably never be worth more than $1000 isn't something I'm going to do. So, question time:

1: Is it possible I've miss diagnosed the oil pressure problem? Is there a common problem I don't know about?
2: Is there some poor-man's rebuild option? could I bore out the cylinders to accept stock xj750 pistons?
3: Can I use my non-yics carbs on a yics-engine? There's a running 650 for sale by me, but it looks like it might have a yics engine based on the single, terrible CL pic. (It's an 81 maxim, just like mine, so it shouldn't, but....)
4: Any cheap and running 650 or 750 (those can be crammed into 650 frames, yes?) engines for sale in/near Minnesota?
5: partout? https://www.instagram.com/zaxbys1337/ Ignition module is a year old and front brake was completely refreshed last summer. Plus, the cafe-ish seat made from a stock seat.

 

oil pressure won't make the valve cover leak. when the valve cover leaks it will make the head look like it's leaking. what you saw coming from the crankcase vent was probably water vapor, no big deal. you should check the valve clearance before you do a compression check. then no matter what the compression is, how does it run? then do one of those cost/benefit things and let your wallet be your guide

 

1Polock covered this if you had excessive crankcase pressure the oil would blow out the vent hose into the airbox before the heads or if you have pods all over the motor.
2 poormans option is another motor 650 or 750 will work
yics motor needs the tci that comes with the motor as the nonyics motor has a different tci and wiring configuration

3 HCS 32 carbs are Hcs 32 carbs may need different pilot jets and needles in 650 depending on year and country to match year of motor but that is debatable use 650 carbs on a 750 need to rejet http://xjbikes.wikidot.com/carb-specs
4 i am not in Minnesota but a parts/donor bike may be cheaper than a motor alone
5 ignition module 1 year old doubtful unless it is an aftermarket one

do not confuse oil pressure with crank case pressure, first is made by a pump second is made by piston movement, have you checked your oil level over filled oil incressess crankcase pressure if it seals off fills air flow spaces or covers bottom of cylinder sleave.

 

Ok: new day, new outlook! Compression numbers after redoing the test with WOT 1-4: 120, 130, 130, 130. Valve clearances were done last year and 6-7 of the shims were replaced with thicker shims. The bike runs great; it's just suddenly throwing oil out much faster. I loosen all the valve cover bolts and tightened everything down going from the center and working my way out to make sure everything was tight there. Took it for a ride (to return the compression tester) and I'm still nearly certain it's leaking oil from the headgasket. It's very wet right around the front center where the head and case meet(and dry up by the valve cover) and appears to be a little wet most of the way around the headgasket. As in the fin below the gasket is coated in oil and the fins below and above have nothing (below might have a small amount). I know the previous owner had the head off at one point, so should I retorque the head studs? I assume the haynes manual has the value and order to torque them (and is hopefully correct)

(and the tci is aftermarket )

 

Oil coming from the speedo gear?

 

You mean the tach? Just replaced the seals and o-ring

 

retorque head first before removing it valve cover donuts can cause leak from valve cover shrinkage but you are sure of the leak being head

 

Pretty sure my non-yics valve cover doesn't have donuts, and that gasket was replaced last summer. Probably gonna retorque the head this weekend then.

 

you are correct. 2 times this week I blew that call

 

well, I retorqued the head today. The top 12 bolts were fine, but the front side nut that's under the head (and right where the leaking was) needed about a 1/4 turn to reach 23 ft-lbs. So I cleaned up the engine a little bit to try to make any leaks obvious and took it for a 20 mile ride. 5 miles in I stopped and noticed one little spec of oil on my boot and some wetness on the right side of the transmission and top of the carbs like the right rear of the valve cover was still leaking a bit. It wasn't that bad, so I continued on and didn't really pay attention to anything until i got home. There I realized my right boot (and lower pant leg) along with my right side panel (where the stock plastic piece goes) were coated in oil, along with the carbs and side engine covers.

Why is a two year old gasket (I misspoke when I said it was one year old) allowing so much oil past it?

 

I would suspect the valve cover gasket is not seated properly in it's groove. The inside edges are tough to see. Suggest removing the cover and lightly glue the gasket to the cover with a removable Permatex type goop first. Once it's tacked in place add some more to the half moons and take extreme care getting the cover properly seated.

 

oil filter cover will leak and get oil on your shoes a little rtv on housing will fix that