06 450 HELP - Engine Grenaded during Vegas to Reno!!

5 replies to this topic
  • LVThumper

Posted August 24, 2008 - 04:08 PM


Well, we tried, and I won't say we failed entirely because we had a great time, but we didn't finish. :worthy:

33 miles in, our first rider went over the bars, the bike flipped over, and the resulting damage appeared to be a busted up rear fender, busted hot start, and some scratches. Off we go and although the rear suspension feels springy, we rectified it at the next pit. The bike seemed to sputter at top end, and although we changed air filters and pulled filter skins between each pit, by the time we were at pit 7, something was wrong. we had already determined at Pit 3 that the sub frame was bent, but now there was oil coming out of the breather tube, so we added some and leveled it off. I left out of the pit and 15 miles later, the bike was done.

Once we retrieved the bike we started to tear into it to see if we could salvage the ride and still get a finish. When we pulled the right number plate off, we discovered our problem, the first and only crash of the day not only did the aforementioned damage, but the exhaust pipe was bent in two places and flatened out between the fame mounting bolt and the exhaust can!! :busted:

Well long story short, there wasn't much oil left, as the back pressure was just killing the bike. The overheating from the back pressure also boiled almost all of the radiator fluid out as well. The spark plug cap / coil was slightly melted too.

Now for the questions / advice request - We have pulled the motor and will look at tearing into it next weekend to replace the top end. What else should we be looking for? The oil that came out looke dirty (obviously), but there were no metal "shavings" only tiny metal flakes like what I normally see from clutch wear. I am guessing piston, rings, replate the cylindar, valve and head work, timing chain (while it's apart), but what else??

I appreciate any and all input.



  • bigred455

Posted August 24, 2008 - 06:01 PM


Honestly I would split the cases and go over everything. Since the cases are split,go with a new crankshaft assembly.Seals bearings also,everything will be back together and you will not 2nd guess yourself.Also check out the cams and bearings,along with caps and where the bearings mount. If there was oil starvation that is the worse place affected.

  • Mike Martel

Posted August 25, 2008 - 12:14 PM


I had my 06 yz450 over heat and quit because I never checked the radiator fluid. Turned out it just melted the coil which made the bike quit. Everything else is ok and the bike runs great after replacing the coil.

Yamahas are almost idiot proof. Thank god for the extended warrenty.
Yes I Lied and said I put fluid in it to the people at the shop.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • KWJams

Posted August 25, 2008 - 12:57 PM


Sorry to hear about the DNF -- but you said there was not much oil left and the bike was "done".

How much is not much and what do you mean done? Did the motor lock up?

You have to determine if all the heat was from oil starvation or what you referred to as back pressure. Back pressure would make the bike run so poorly that you would think it would not be able to run fast enough to create the heat like you describe.

My advice is a complete disassembly checking for warped parts and anything out of spec -- and then retire the motor to play riding and drop a fresh motor in the frame.

Not much consolation but you will have to ask yourself is it worth another DNF at the next race when you may be leading?

  • SUnruh

Posted August 25, 2008 - 06:35 PM


the Fram version of what bigred455 said:

"Pay me now, or pay me later!"

take the time and do it right now. split it and see what is truely "done". R&R what needs it and rock on.

  • LVThumper

Posted August 26, 2008 - 09:38 AM


Thanks guys. I figured as much. It looks like this upcoming long weekend will be just that, a LONG weekend! :thumbsup:

I had a blast and it was worth it! Can't wait for next year!


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