2006 YZ450F one o-ring created $1000's in problems


11 replies to this topic
  • bentley

Posted January 16, 2009 - 04:41 PM

#1

I'm new here, but I have used the site many times for help. I have a 2006 YZ450F that was purchased used. When I purchased it the bottom end had just been re-built with one ride on it. I rode it for a few months and on my last ride it started smoking out the over flow tube from the top end. It was a white smoke. I rode back to the car as I felt my clutch tighten up. I put it in the truck and took it home when I changed the oil it was black(only one ride on fresh oil). I then took a look at the radiator and it was empty! So I started to fill it up and it leaked from the tube that goes into the head and I found that the o-ring was bad. So thinking I had found the problem I replaced the o-ring, changed the oil, and everything felt fine. I rode it again and the radiator fliud was gushing out the radiator overflow tube now at high RPMs. I assumed it was a head gasket. So I took it down to the head gasket replaced it, along with my clutch that I found out was about to go(jet black with grooves). When I built it back up it wouldn't start. I then thought I over tightened my cams and that was true(I recomened 5 foot lbs not 7) I losened them and it would kick over but not start. My mecanic has a compression tester and we found that I was losing 40% compression, thats the piston or rings. After taking it back down to the head I found that the pison has wear in it and the cylinder was also worn down and the oil channels were almost gone and on top of that my oil pump was about to go....what a drama! So now I'm looking to replace my piston, cylinder, oil pump, clutch, etc...has anyone ever had a problem like this, any word of advice as I proceed on the fix? Anything else I should look at?

  • sacfelix

Posted January 16, 2009 - 06:20 PM

#2

While your in there change the timing chain as well.

  • bentley

Posted January 16, 2009 - 06:48 PM

#3

Thanks, I have read that the timing chain is a common issue with these 450's. My chain looks fine, but then again so did my piston at first look. I suppose it's not worth taking the risk for a $30+/- part.

  • DBMX 925

Posted January 17, 2009 - 02:44 AM

#4

Are you saying the o ring caused the problems or because you were looking you found all these other problems. I had the same things, black oil (grooves in clutch basket) Radiator low (hadn't checked it all summer) piston and rings, timing chain replaced at 75 hrs. Now she is back to normal...... a delight.

  • bentley

Posted January 17, 2009 - 07:17 AM

#5

No, I don't think it's possible to have done all this damage from one o-ring. I'm sure it burnt up the clutch plates but not the other stuff. I think that was from the previous owner as I have not had the bike to long and things like wearing the cross hatching on the cylinder takes some time. I think getting into the motor was good so that I could see all these problems, otherwise it would have certainly blown up, created more problems, and probably while I was out on a ride. I ride hard but I ride right and take care of my bike, so its a huge bummer for this to happen to me. I'm glad to hear after you replaced all those things that it was back to normal, I cant wait to get back out on it! Dave- was your cylinder OK after getting in to it?

  • grayracer513

Posted January 17, 2009 - 09:16 AM

#6

No, I don't think it's possible to have done all this damage from one o-ring. I'm sure it burnt up the clutch plates but not the other stuff.

So, you don't think that riding a liquid cooled engine back to your truck with no coolant had any effect on it? I'd say all the damage was from the loss of coolant, and also that you bear as much responsibility as the O-ring does, since it was you who decided to run the engine in that state. You should have refilled it in the field or towed it back.

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  • bentley

Posted January 17, 2009 - 04:33 PM

#7

I'm sure that riding back to my truck with no coolant made it worse. The only thing I don't think I did was put grooves in the clutch basket, I also wish I would have known that I was low on coolant at the time. Had I known I would have put water from my camel pack in it just to get back since I was on a very technical single track called Kerry Canyon up at Colsen Canyon. There was no option to get towed out of the place I was at. This was an expensive lesson learned! If my timing chain looks fine do you guys think I should still replace it along with everything else? I took another look at it and it looked good but after reading a few posts it sounds like most will replace it after what happened to my bike.

  • mkporn

Posted January 17, 2009 - 05:51 PM

#8

I'm sure that riding back to my truck with no coolant made it worse. The only thing I don't think I did was put grooves in the clutch basket, I also wish I would have known that I was low on coolant at the time. Had I known I would have put water from my camel pack in it just to get back since I was on a very technical single track called Kerry Canyon up at Colsen Canyon. There was no option to get towed out of the place I was at. This was an expensive lesson learned! If my timing chain looks fine do you guys think I should still replace it along with everything else? I took another look at it and it looked good but after reading a few posts it sounds like most will replace it after what happened to my bike.


Replacing the chain should not even be a question needing to be asked. If you have it opened up, replace the chain. If it goes, not replacing a $30 chain turns into a bill that could be mor than a grand...:thumbsup:

  • 426 NOOB

Posted January 17, 2009 - 10:23 PM

#9

Replacing the chain should not even be a question needing to be asked. If you have it opened up, replace the chain. If it goes, not replacing a $30 chain turns into a bill that could be mor than a grand...:thumbsup:


What he said ^^^^

  • moto T

Posted January 18, 2009 - 03:26 AM

#10

I would say that grooves on the clutch basket is normal for an 06. I had to replace mine after about 50hrs, buy a billet basket and you won't have that problem anymore. Also, if you oil pump went you might want to check your crank, there is a line that pumps directly to it.

  • Polar_Bus

Posted January 18, 2009 - 08:35 AM

#11

any word of advice as I proceed on the fix? Anything else I should look at?


After reading this post I still don't quite understand it, sorry to rub salt on wounds, but here's a few tips:

NEVER buy a hybred race 4 stroke that just "had the bottom end redone".

This for SURE spells a lifetime of questionable engine relibility. 90% of people who granade an MX 4 stroke engine don't have the money to CORRECTLY and COMPLETELY repair the extensive damage. They are fixed "half-a$$" then the person quickly sells the bike knowing it's a ticking time bomb....


If you see antifreeze leaking all over the place, STOP ! Let the bike cool, open the cap, and see if the system has fluid, if you can't see any fluid assume the system has no fluid, DON'T drive the bike. These new bikes have a minimal amount of coolant and oil to keep the weight down, so any less fluids will immediately spell disaster..

  • bentley

Posted January 18, 2009 - 09:02 AM

#12

Like I said lesson learned...the guy I purchased it from gave me an invoice with over $1300 worth of part for the bottom end and I even went to the shop that did the work and asked them about it. So I felt that I followed up with the work that was done and it was a good local shop that I trust. I still agree with the 90% of people not puting it back correctly, and at the time the guy could have just had the mechanic replace only what was broken and not replace what looked "ok". I'm the 10% that pays to fix it correctly thats why I have a parts bill of over $1600 so far...most OEM replacement since I figure OEM is best for most engine parts.

Trust me, if I could see the coolant leaking I would have stopped. It was a slow leak that was hitting the head/head pipe and wasn't dripping from my bike. I think it slowly leaked over the period of two rides on the same day and I'm now a believer in checking it after every ride!





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