'05 YZ450F-what do you guys think about it?

30 replies to this topic
  • revolucien

Posted November 03, 2004 - 05:43 PM


i think the yamaha guys suck for not getting the aluminum frame out for first year testing on the 4 stroke. i don't usually buy a bike in the first year after a major change to see what happens.
now if they throw it on the '06, it will probably be '07 before i get a new bike :cry:

  • condog_aus

Posted November 03, 2004 - 07:28 PM


WRONG! YOU HAVE TO BREAK IT IN HARD, but you have to cool it down every 10 mins of riding. FORGET what the manual says.

Yeh im sure you have broken in more engines than yamaha and pulled them apoart immediately after breaking them in to determine the best break in method.
Sure our opinions differ but dont rush so full on into saying that you know better then yamaha. If you do than go get an engineers job with them. Im sure Yamaha will back up their advice with their wallets. Id like to see you shelling out cash for engines that are blown up by running them hard while new. :cry: :cry: :cry:

  • SureBlue

Posted November 03, 2004 - 08:09 PM


Dear Condog, please read the motoman article
and see if it makes sense to you.

My bikes and the numerous ones I have supplied have been breaken in that way without problems. The list is long.
It is the combustion gas pressure that presses the piston rings against cylinder. If not enough pressure, the rings seat incorrectly. Machining tolerances are small, so if the engine breaks down, it would do it in any case.
The engines are test run on assembly lines, and do not think they are babied, they get beat hard.
What the manual says is only a way manufacturer avoids liability claims, but feel free to go the manual way.

When you pull out your babied piston from your bike, see if it has blowbys or clear shiny piston walls like this one has
Posted Image
Kind regards from Finland.

  • condog_aus

Posted November 04, 2004 - 12:13 AM


Interesting reading. The jury is still out. Thanks for the link, From Aus. Gods Country.

  • ovrrdrive

Posted November 04, 2004 - 01:31 AM


I've known about and heard about mototune's breakin for years, and I still don't buy it...

Everything on that guys site goes like this, "I know that everyone else does it this way, but I have learned the secret and get 20% more power by doing it like this. Forget what you know, this is the right way..."

There is no way that one man could figure out so many engineering secrets that go completely against everything the manufacturers that actually build the engines think they know. He's a smart guy, no doubt about it. But my $7000 bike got broken in by the book and runs perfectly.

The only thing I do a little differently than the book is I'm not afraid to get on it once in awhile and let it pull a load about halfway through the rpm range. From my past experience with different recommended breakin techniques that helps seat the rings. Otherwise I took it easy on the motor for about the first 5 hours before I really wound it out. After the first oil change I was a little more free with it, but I didn't really rag on it until I had probably 10-15 hours on the bike.

I will never do a mototune break-in on one of my engines. I just don't buy it.

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  • YZ250F_Rider

Posted November 04, 2004 - 04:02 AM


I will never do a mototune break-in on one of my engines. I just don't buy it.

He never thought of it first. It's called setting the rings, and has been done like that for as long as I can remember hearing about engines.

No ring/cylinder mating surface is perfect and it will leak at first. The intent is to get the rings and piston wall to initially wear rapidly so they seal better. This minimizes the blowby of the combustion and lets the pressure of the combustion push the piston down harder (more power) instead of just blowing past the poor mating surface of the ring and cylinder.

Most of the plated cylinders are pre-worn (machined) so that the cross hatch has flat tops instead of peaks. This reduces the time it takes to seat the rings. But it does not remove the need for it.

  • tricksta400

Posted November 04, 2004 - 05:54 AM


yo, this thing is amazing. it took me like 4 laps to get the suspension tuned to my liking and get used to the power...but this thing rips! The suspension is amazing and i did the 75footer and it didn't bottom!! That awesome. Now i can beat the kids i couldn't beat with my 400, i would recommend this bike to anyone that wants the best bike in the world. i think its better than the 04 honda, i rode that and didn't like it. This thing is amazing. and the power is still there and it dosen't lag. i might go down a tooth on the rear though, and really get rid of the chain it sucks balls.

  • Neysbo

Posted November 04, 2004 - 08:10 AM


Does anyone's 05 YZ450 seem to run extremely hot compared to the 04. Is it that they are running that lean.

I put Engine Ice in, went to the 170 main and lowered the clip, this helped some.

The plug still comes out very lean looking though

  • Thumper38

Posted November 04, 2004 - 08:58 AM


Its been pretty cool here in PA so I have not noticed the heat issue but I do feel that it is a little lean! :cry:

  • wr_power

Posted November 04, 2004 - 08:40 PM


Check out the Nov. issue of Dirt Bike Mag. They have a great right up on the 05 YZ450F.

  • SureBlue

Posted November 08, 2004 - 12:12 PM


Came back today from the Gotland Grand National, world's largest enduro race held on saturday in Gotland, Sweden, with over 2300 participants racing. Look at:

Talked with a guy there who is a top brand sports car mechanic and who earlier had worked as mechanic with bikes and had received schooling at a motorcycle plant in Japan.
He told me that the 4-stroke engines get break-in oil at assembly line and they idle warm about 5 minutes, then they dyno-run THE CRAP out of them for some 5 minutes. If everyting is OK, the computers give green light and they suck the oils away for recycling. The ones that failed, some 10% perhaps he said, got the red light and the engines got torn into pieces by engineers for R&D purposes. This is the initial factory break-in! Unfortunately he adviced me not to mention any brands, I only can assure the cars and bikes he works/worked with are top level.

Naturally everybody does his break-in the way he wants. And I do not even suggest you notice any difference between bikes broken in either way, by manual or by motoman. And sorry, I cannot send checks if you break something doing the motoman way, but if something is prone to fail it will do it anyway regardless how you brake it in. Just don't let it overheat.

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