250r rattle noise [Archive]

ATC350X 85

11-19-2002, 07:09 PM

I just did the top end on my 86 250r and when you rev it up you can here this rattle noise coming from the cylinder. I know my circlips are good, my rings are lined up and everything is good in there or so i think. Its a stock bore with a new Wiseco piston, rings, pin circlips and a new Honda bearing. I put a new Honda base gasket and I used a CR head gasket. Is it possible the CR head gasket is the cause of this, cause it is thinner and ups the compression? Im gonna take the head off over the weekend and see what it looks like in there and get a ATC head gasket for it and see what happens. Also could this just be a new break in noise? It only has 40-50 minutes on the top end? If anyone has any ideas on this please tell me, this is my baby.

Lots_Of_Nothing

11-19-2002, 07:11 PM

usually when it does this, it is because the piston is too small and it is slapping off the sides of the cylinder....but idk

Dirtcrasher

11-19-2002, 09:02 PM

I haven't heard to many break in noises. Something is outta spec and hitting something or slapping around or, is something vibrating? Give your baby some surgery!

ATC350X 85

11-19-2002, 09:28 PM

Im gonna open it up take a look around and see, also im gonna put the right head gasket back on it.

freaksfix

11-19-2002, 11:20 PM

not to insult you but did you get the right size bore head gasket??? I dont know of the tolerance's off hand, but you might not be able to use a high comp. piston with the thiner gasket???

OldSchoolin86

11-19-2002, 11:35 PM

Unless you resleaved it I'd bet it's a good old case of piston slap.

tony_250r

11-19-2002, 11:40 PM

With the CR head gasket the compression was rasied, you may need to run race fuel now, VP Red or C12.

atc86r

11-19-2002, 11:42 PM

do a compression test on it and let us know.

250rAL

11-20-2002, 11:29 AM

When I had my '85 R rebuilt in 1990 at the Honda shop, it had a ticking noise in it. I took it apart to see if I could see anything wrong and discovered a small "dent" on the very bottom of the piston skirt (Honda piston). The piston was hitting the crank slightly at the bottom of the stroke. I filed the spot off and the noise was gone.

ATC350X 85

11-20-2002, 06:59 PM

I just realized that the head gasket i got is for a 90 Cr 250 and the bore on that was 66.40 not 66mm like the atc 250r. I wonder if that has any effect. I tried to take it apart today with some crap tools cause all my good ones are at work, I broke 2 12mm sockets trying to take off one motor mount bolt, damn crap tools. But more than likely its gonna be piston slap and im gonna have to bore it over. How much is the question, hopefully the slapping didnt cause any damage.