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View Full Version : Engine is apart....Again!!


JhallettEX
05-09-2002, 07:40 AM
Well guys I began takin the engine apart last night to inspect for any damage, and also to take my head off to get Ported and Polished, CDRacing is doing it for me. Anyways I have a few questions about some things I ran into:

1) When you take the cam sprocket off you have to rotate it once to get to the bottom bolt, which makes you looseTDC. Do I leave it like this or do I need to rotate it to TDC again. I have everything off, meaning my cam, sprocket and head and I can see the piston is 3/4" down into the cylinder. Let me know on this.

2)When I put it back together do the lobes face up or down, When I took it apart they were down.

3) Question about gaskets: 1) The head gasket is the one that is under the cover correct? So then the gasket that is inbetween the cylinder and the head is the base gasket? Do I have this right? When i order my new gaskets I want a xr400 head gasket and what base gasket?

Thanks alot, I will keep you informed on the progress
JhallettEX
05-09-2002, 07:57 AM
Just snapped a few pics to post, just wanted to see if anyone saw anything not normal.
Texan32
05-09-2002, 07:58 AM
You have 3 gaskets.
1-valve cover gasket...that is the gasket that goes between your head and the calve cover.
2-head gasket...this is the gasket that goes between the cylinder and the head.
3-base gasket...this is the gasket that goes between the cylinder and the crankcase.

I think i hear a couple people say to use the xr head gasket and just use a thin layer of RTV ot the base gasket.
JhallettEX
05-09-2002, 07:58 AM
2nd view........
PsychoDave
05-09-2002, 07:58 AM
AS LONG AS THE ENGINE IS AT (TCD) ON THE TIMING MARK. ALIGN THE CAM SPROCKET WITH THE MARKS ON IT, AND THE LOBES OF THE CAM FACE DOWN (DONT WORRY YOU CAN NEVER BE OUT 180 WITH THE TIMING.....THE 400EX FIRES THE SPARK PLUG EVERY STROKE)

THE GASKET BETWEEN THE CYLINDER AND THE CRANK IS THE BASE GASKET....BETWEEN THE CYLINDER AND HEAD IS THE HEAD GASKET (HEAD GASKET USUALLY HAS METAL, BASE GASKET IS A FIBER GASKET) GOOD LUCK
JhallettEX
05-09-2002, 08:01 AM
Dave, then what is the gasket between the head the the head cover?

****Edit****Sorry Tex, thanks
Texan32
05-09-2002, 08:02 AM
Did you miss my reply? Look up...
PsychoDave
05-09-2002, 08:06 AM
1-valve cover gasket...that is the gasket that goes between your head and the calve cover.