Yz450f seize

7 replies to this topic
  • BigBoyBike

Posted May 13, 2014 - 10:56 AM


Hello I got a 2003 yz450f and the carb was leaking bad so I fixed the needle and seat and I didn't pay attention to the fuel adjuster and when I got it running and it was idling for about 2 minutes and the choke was on also and when I shit the choke of it sized my buddy told me that it was a hydro seize I don't know what to do please help thanks

  • DGXR

Posted May 13, 2014 - 11:29 AM


Never heard of hydro lock related to fuel or choke issues.  Not sure if your bike has manual or auto compression release.  You said it seized but I have to ask, can you kick it over using manual compression release?  If not, or if it has auto compression release, try removing the spark plug and see if it will turn over.


Only hydro lock I've heard of is when the engine ingests water (dropped in a river, etc). This can be cleared using the compression release, if the engine has it. Potential damage due to hydrolock (depending on the crash circumstances) can be blown head gasket, bent con rod, bent crank, damaged crank bearings, and other.


Letting a bike run high idle with choke for 2 solid minutes is too long IMHO. You should be able to shut off the choke after 30 seconds and the bike should idle.  Ride under moderate throttle until it warms up more, then let 'er rip.

  • BigBoyBike

Posted May 13, 2014 - 11:54 AM


It has a manual compression release haven't tried taking the plug out to see my buddy said it should release when I take the plug out

Edited by BigBoyBike, May 13, 2014 - 11:56 AM.

  • grayracer513

Posted May 13, 2014 - 02:37 PM


It has a manual compression release



Not if it's an '03 it doesn't.  That little extra lever is the Hot Start.  It could have had one added, but only a very few ever had that done.


The most likely cause of a seizure in an '03 is a rod bearing failure.

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  • BigBoyBike

Posted May 13, 2014 - 02:40 PM


Oh ok

  • Kylediffley

Posted May 14, 2014 - 07:44 AM


How what should I do?

Disassemble the bike. Head, cam, cam chain, tensioner, valves, and take off cylinder to inspektør.
How many hours would u say r on the bike?
How many hours on the oil and rings?
Was there oil in the bike?

  • grayracer513

Posted May 14, 2014 - 02:12 PM


You are going to need to pull the engine apart and find out what locked up, if it is actually seized.  You won't know anything until you do.

  • BigBoyBike

Posted May 14, 2014 - 05:48 PM


Well I got it un seized found out I hydro locked it with gas any tips on draining an engine?

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