Like the title says, I got my 85 running again, but it makes this horrible noise in the motor somewhere. It has always done this on previous rebuilds and wonder if this was the cause of it breaking a thrust washer and siezing my motor. Do 85's generally make a loud "slapping" noise when running? IT is most noticeable when getting on the gas..

RoostKing...

 

I don't know if theya re known for that, but if you bored it out you will need to rejet so it could be a lean knock.

 

The word "rebuild" has allot of different meanings. What exactly did this rebuild include? I assume you merely bored the cylinder and installed a new piston. If so, did you get the piston yourself or did the boring shop provide it as they should. Either way, you need to make sure that the piston is right for the bore size. However,since you say you had this noise after previous rebuilds, I think your problem is in the bottom end. My first guess would be a rod problem. You should have checked for up and down movement of the rod on the crank (there should be none). If no problem is found there then the top of the rod should be measured (although the bottom usually goes first since the degree of rotation is greater). A main bearing could be failing but you would have a severe air leak problem long before these bearings made any noise.
Upon rereading your post, I notice you mention the thrust bearings going out. If you are talking about the ones on the big end of the rod then you must have rebuilt the crank. I guess I will have to wait for you to clarify what you fixed before I can be of any help.

 

Sorry for the lack of information. Yes, all I did was get a bore and hone, with the machine shop supplying the Wiseco +.020 piston kit. I wish I could have checked for rod play before I put t back together. As far as the thrust washer/bearing, it is on the small end of the rod where the piston is. It goes between the rod end and the inside of the piston. It sounds like this is not a normal sound out of the 85's. Either way, Im going to run it this weekend and if she blows, show blows...

RoostKing...

 

I highly recommend that you check out that rod immediately! If the noise is that loud, your quad could be in for a world of hurt. In a worst case senario, the rod could let loose entirely and ruin one or both halves of the engine ($$$$$). This worse case may not be real likely but running an engine that you know has a major problem like this is asking for trouble.
The most it is going to cost you to check the rod is an hour of time and maybe a couple gaskets. Stop torturing your quad! You will regret it!