Hello all,

I had my 1985 13b just rebuilt and got it running. It was running a little rough so after about 10 mins I decided to do some checking, after doing a compression test the front rotor is getting 120psi the back is only getting 65psi so I feel the apex seals are not seated. I did take it for a drive and got it to operating temp brought it back and did a test again with same results. I am running 2 stroke oil with fuel just in case someone ask that question.

My question is how long should it take for them to seat?

Thanks for any help I get.
Greg

 

Bump... cause I've got the same question.

 

Your seals were installed correctly right? Is it 65PSI on all 3 sides or just one?

 

More accuritly my question is what is the recomended break in?

but it falls under the same catagory.

 

Yes seals were installed correctly I helped/watch builder and he explained as he went and showed the correct way and the wrong way so I could learn. As far a compression it ranged from 1 72psi 1 60psi 1 65 psi I just round out to 65psi. After do some research different builders say anywhere from 2000 miles to 5000 miles so I am going to go on a little driving and keep testing. I called the builder and that was his suggestion also and if after 2k miles it does not get better to bring it back and we will rebuild it again.

 

My concern with this "drive it for 2000 miles", and we will see is if something failed, is how much damage will be done to the engine in that time? I would drian the oil and look for metal shavings. Just to be blunt something isn't right!! Take it back to the builder and figure out what went wrong. Have him look for the issue(s) or you can but that my void any warranty.

 

ugh.... what kind of rebuild.... new/used apex seals, condition of housings (chatter marks, chrome flaking) the seals need to where in to match the housings. check the compression every couple hundred mi. if it keeps getting better than your ok if it dose not change then you have a problem

 

New Apex seals and springs the housings had some marks but no chrome flaking. My plan this weekend is to drop the exhaust and verify apex seals look ok and if so drive it about 50 miles and check compression again to see if it improves.