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mxdude1986

Yz400f Update Please Help!

5 posts in this topic

OK SO AFTER NARROWING MY PROBLEM DOWN TO THE HEAD GASKET I DECIDED TO OPEN THE ENGINE AND CHANGE IT OUT SO I TOOK THE CAMS OUT AND PULLED THE HEAD OUT I DID NOT MESS WITH THE VALVES HAS ONLY BEEN 6 HRS SINCE THEY WERE CHECKED AND WERE WITHIN SPECS DO I NEED TO DO ANYTHING TO THEM?, SO I GOT THE HEAD OUT AND THIS IS WHAT LOOKS LIKE WHAT YOU GUYS THINK? I DONT PLAN ON CHANGING PISTON OR RINGS SINCE BIKE HAS BEEN RUNNING REALLY STRONG. WHAT YOU GUYS THINK? HERE ARE SOME PICS.:thumbsup:

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MY HELPER !

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lets see some pictures of the cylinder walls, atleast one of the "side" of the wall and the "front" of the wall. if the crosshatch doesnt match then things are a little worn...

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Place the head so the valves are pointed down (like the head was setting back on the jug). Squirt a fair bit of carb cleaner in the exhaust port and the intake ports, wait a minute or two and then raise the head without tipping it and dumping the carb cleaner out. If you see some seepage, then whatever valve you see is not sealing. The '99 400 has steel valves (unless replaced somewhere along the line with ti') so if the seepage is only a little, then you can probably get by with cleaning the valve, seat and then lapping the valves.

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How many hours do you think are on the bike??

While your are already into it for a topend gasket kit make sure all is good before bolting it back together. Check your piston and valves out well if it has been leaking coolant in. Your cylinder wall should tell you if there is trouble. It is apart now so pulling the jug to have a good look wouln't kill you. If it has higher hours the timing chain be worth a close look. Why did the head gasket start leaking...could the head be a little warped??? Just some things to think about before buttoning it up.

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