98 Evo Rocker Box Gaskets
 

I just replaced the Rocker Box Gaskets in my Evo. I used the James Gasket set with the metal and silicone base gaskets. The front box was leaking and we saw the two leak points in the old HD Gaskets. The only problem was that the James Umbrella gaskets in the new set wouldn't seat properly in the middle Rocker Box. Hence we ended up using the HD Umbrella gaskets. Everything went well except now I'm getting pressure in the oil filler box to the point of pushing out the dipstick. Thoughts?

Sounds odd. Double check your work? Did you do any work in the cam chest? YD

No, but I went back to it today. Started it up and let it idle for a while. The dipstick came up about an 1/8" but did not come out. Took it out for a ride. After about 5 miles, checked it out again. Dipstick was no further out and if anything, completely seated. Strange

A few years back I was helping my brother do a cam change on his 97 EVO motor (top breather). Since we pulled the rocker boxes to install the cam we replaced all the rocker box gaskets with new gaskets. When my brother went to ride the bike it blew out the oil dip stick. We finally figured it out, the local shop where my brother bought the gaskets gave him a set for a bottom breather motor (pre 1993) which did not allow them to breath out of the top end. Check and make sure that you have the correct gaskets for your year.

You are definitely better off with the green HD umbrella valves, they're better than anybody else has out there. As for the pressurized oil tank, you sure you didn't swap the rocker spacers? The front with the rear and the rear with the front as this will change the location of the umbrella valve and It will do what you're saying.

No, did not swap. We did the rear first and then the front. As previously replied, it didn't come out today when I ran it, Starting to believe a new O-Ring on the dipstick will solve the problem if there is any, That O-Ring is 21 years old. Thank You everyone for the input.

No, did not swap. We did the rear first and then the front. As previously replied, it didn't come out today when I ran it, Starting to believe a new O-Ring on the dipstick will solve the problem if there is any, That O-Ring is 21 years old. Thank You everyone for the input.

Too much oil in the tank will also do this, I assume you drained the oil when you did the project. Maybe there is just too much and you need to drain off a half of quart. Sometimes it is easy, not often, but sometimes. Good luck.