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Z400 Problems
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Posted by: Boggs#3

Ok my friend has a 2003 z400 we was riding the other day and it just quit.It has no compression at all. We havent taken it apart yet i just wonder if any one knows what this could be? It turns over as if the was no spark plug in it. There is very little compression coming out the exhuast when you turn it over? Any help greatly apreciated. Thanks

Posted by: jonboy

Check and see if the plug is in fact threaded in tight, also check to see if there is any blow by at the head gasket.

Posted by: Boggs#3

Ok how do i check to see if there is any blow by at the head gasket? Thanks

Posted by: jonboy

you will hear air hissing out, also check to see if it is leaking coolant or oil. I reread your post if it just quit on you it may have jumped time and the valves are not opening and closing when they are supposed to.

Posted by: Boggs#3

It not hissing or leaking any where. What would it tear up if it jumpt time? He was giving it heck when it happend he thought the timming chain broke but it isnt. How often does jumping time happen? Thanks

Posted by: jonboy

If the timing chain was stretched it could cause it to happen, especially if he over revved it.

What would it tear up if it jumpt time?
If it jumped time bad enough for it to cause the valves not to open and close at the correct time, one ofe the valves could come in contact with the piston and damage the piston or possibly bust a hole in it. As well as damage the valves.

Posted by: Boggs#3

Id say thats what happend because it was on a flatt track messing around and i think he was wide open. Thanks well see what happend this weekend were going to tear it apart.

Posted by: jonboy

Keep us posted on what you find. I am curious to see what happened

Posted by: Sandgod4

Super low compression is a valve issue..It means both ex and in valves are open at the same time even if it's only for a fraction of a second. The engine cannot create enough comp to fire when this issue occurs..

Posted by: 400exrider707

quote:
Originally posted by Sandgod4
Super low compression is a valve issue..It means both ex and in valves are open at the same time even if it's only for a fraction of a second. The engine cannot create enough comp to fire when this issue occurs..

More than likely jumped time which is all too common on these motors with their crummy OEM cam chains, then bent a valve or two and now wont run because the valves are not seating.

Posted by: Boggs#3

Ok i will keep you guys posted i think were going to do it saterday thanks for all your guys help

Posted by: Boggs#3

Welp guys to start off the bolts that hold the cam down was all broke off 3 of the valves were broke off everything looks burnt and there is a hole in the top of the piston. So he hast to buy a whole head and eveything. The local honda shop said it was from riding long wheelies and no oil was getting to the cam.

Posted by: Sandgod4

Well it's time for an Athena. Somebody will have a used head complete.. Do not buy new and do not buy from a stealership.. There are plenty of used things in this day and age of the internet. You just have to do a little searching..

Posted by: smoothie

man good luck with that. sounds like a head ache lol. definitely a great opportunity for a big bore, hot cams good valves....all that great fun and expensive stuff. end result will be more than pleasing if you do it right.

Posted by: rockman

OUCH.. sounds like he sure did a number on that top end.. thats ok, the Z needs a big bore anyway. Its fun pissing off 450's

Posted by: jonboy

Over revving will do the same thing. I kind of figured that is what happened. Done the same thing on a raptor a while back.

Posted by: rockman

quote:
Originally posted by jonboy
Over revving will do the same thing. I kind of figured that is what happened. Done the same thing on a raptor a while back.

LOL i did the same thing with a 250x once.. smashed the piston into 30 some pieces. I've still got that piston too. I'll post some pics of it, nasty stuff, the head was destroyed.

Posted by: Boggs#3

He is looking for a used head if anyone has won. Thanks

Posted by: Sandgod4

Contact my bro Buddah. He just sold a head and ported jug to a guy. I believe the guy he sold it to now has his head and jug for sale.. carlhothan@msn.com is my bro

Posted by: jonboy

Yeah same here. Plus it twisted the connecting rod, head was destroyed, and all five valves were broken in a couple of pieces with some jammed into the piston. It was a big mess.

Posted by: z rider2

yep, i'm the guy that bought buddahs head and jug. I sold my stock head with cams valves everything for 200$. i still have the cylinder and stock piston, but kinda wanted to keep em. by the way the 450 runs awesome

Posted by: Sandgod4

Here's you big chance on the parts your looking for..

http://www.z400central.com/invision...topic=67666&hl=