top end rebuild

[polabareus]

Ok, I just had the top end on my 84 big red rebuilt and Im wondering what to expect from a rebuilt engine. Should I break it in? Do they normally burn some oil following a rebuild. Basically I just need to know whats normal following a top end rebuild. Thanks,

[roofinggun]

I would take it easy for a while, at least a few hours. You may see alittle blue in the exhaust for the first 5 0r 10 minutes because a lot of people put oil in the cylinder above the piston so the jug and rings aren't damaged on the first few strokes. If it was just reseating the valves you shouldnt have any issues.

[polabareus]

see what gets me is that I had it rebuilt because I heard a knocking noise on acceleration and was told it was the piston clearance. They bored it out and put a new piston in and I still hear the noise,,. What could it be?

[roofinggun]

Maybe rockers or possibly transmission. Does it knock when you rev in neutral?

[polabareus]

yes, it does make the noise in neutral.

[TRI-Zbrian]

rod knock?????????

[polabareus]

Im not disagreeing with the rod knock theory but isn't that something they would check or fix when rebuilding the top end? (keep in mind, I know Nothing!)

[polabareus]

oh, and if it was a rod knocking wouldn't it be knocking all the time, not just when I give it gas?

[TRI-Zbrian]

if its is in the early stages of starting to go it will only do it when u rev the engine atleast that how it works on car engines ive seen engines sound fine when idling and at low rpms but when you let into them they sound like a machine gun going off. id bet you have something going in the botom end slowly but soon enouph it will get serios.

[polabareus]

So it should give some warning then before it breaks? I just don't want to have the damn thing blow up while im riding it.

[TimSr]

If I understnd right, you only get a little bit of a knock when you first give it gas, and its coming off of idle, right? It doesnt knock at higher RPMs?

I had an 86 200x with this problem, and a valve adjustment, and some 93 octane fuel solved it nearly eliminated it. I also had a 200sx which had the problem to a much greater extent. Eventually the one way bushing on the centrifugal clutch went, and when I had it apart to fix it, I noticed an awful lot of slop in the timing chain, so I replaced it while I had it apart. Miraculously the knock all but disappeared upon reassembly.