My beautiful YFZ motor...

[The Quad FaJa]

who built the motor?.....thats the best question!!! I had an 04 YFZ and the tranny went out after 3 days and then the motor was knocking after about 6mo's

[Nightbreed]

hinson clutch wont do anything, stock components work no different and are way cheaper. But my motor has ran great, i never had a valve adjustment and put a piston in like 6 months ago, but it was time for it to blow up comming up to its 3rd year on racing.

[Ride1Rob]

welll mine must be a dud. i change the oil every 2 rides. i have replaced everthing in that engine. i seized it twice, blew a hole in the head and cylinder and many other things. its been good lately **knock on wood** but maybee becuase i have replaced everthing in the engine

I think your problems have come from who was (supposedly) working on your bike. The jetting on that thing was so lean when you blew the hole in the head. The plug was almost ghost white when Earl pulled it outta there. And another of your problems is... HOW MUCH Motorwork HAVE YOU GOTTEN DONE? If you max out these motors your not going to get much life out of them .

[DCR_Marcus14]

My motor was stock. It didnt have any work done to it. I guess it had a leaking head gasket, and that eventually made it seize.

[Gunnslinger]

Ride1rob-
I think your problems have come from who was (supposedly) working on your bike. The jetting on that thing was so lean when you blew the hole in the head. The plug was almost ghost white when Earl pulled it outta there. And another of your problems is... HOW MUCH Motorwork HAVE YOU GOTTEN DONE? If you max out these motors your not going to get much life out of them .
The plug turned white because he rode for 3 laps with the whole in the head and as for the guy who supposedly worked on it and jetted it-i stood there and watched him and when he checked the jetting after the build and 2 days after(after his next race) the build it was a nice chocalte brown-so it was not the guy who "supposedly" did the work-he had that bike working long before this happened-53YFZ450 rides very hard and sometimes past the bike so these things happen and it is also known by Yamaha dealers every where that the 04's for the most part have a lot of issues.

Not trying to be a smart a$$ just putting in what really happened and not liking when people knock my mechanic-he does alot better work in half of the time and alot better rates!!

Race bikes and such are what he does!!!!!

Still think you are cool just wanted the record straight-53 rides at full throttle 4 - 5 nights a week so he is putting the bike through alot of painful work and these things will happen!!!

[Eruption]

Geez that thing hand gernaded!  What does the head look like?

[mudnuri]

Holy Crap! Thanks for sharing. That's racing!

[Picow18]

Wow, good luck on the rebuild!

[The hyrbid kid]

your sick man

[yamaha350r]

what happend to it?

[Simulcaster]

I have seen this before when the plug comes loose and sucks sand in through the top. Your plug should be another bolt to check before you ride.

[DCR_Marcus14]

my head gasket leaked coolant into the cylinder and made it lock up.

[MIARAP1]

So let me get this str8.. you rode for 3 laps after the hole was made and didnt feel any performance difference.. When you blow a head gasket you should be able to tell right away do to white smoke, from the coolant being burned, coming out of the exhaust...

[53yfz450]

same thing happemd to me. it actually felt faster. and then boom

[MIARAP1]

Well then its settled.. Run some coolant in your fuel for a quick HP boost

[Simulcaster]

sounds good and keeps the motor builders in buisness

[Chuck_Norris]

really mine got slower. no lie

you are not doing something right then, who is tuning your bike?

[DCR_Marcus14]

getting one of my motors back today, but that one in the pictures isnt getting rebuilt, the head was fine though, the piston barely hit it... lol

[TurboBanshee_kid]

I will buy just the bike from you with no engine for $2000 and i will put my banshee engine in it.  Get back to me

[Old_School]

Orange450- so it leaked coolant and you hydrolocked the motor?  From what I understand what blows head gaskets is intense cylinder pressure or a loose head.  You said the motor was stock? I don't know too much about these new mult-valved 4 strokes but either a bolt on the head could have came loose (caused by vibration and/or high rpm) which cause the gasket to blow or long and high rpm intervals could have lifted the head and hence a blown gasket. I could be wrong but that's what I've seen on 2 strokes. What's the compression on those 450's and how many hours did you have on it?  -Mark

[The Quad FaJa]

same thing happemd to me. it actually felt faster. and then boom

cause water dose not squish like air...so the motor was building compression...makes the bike faster till the lock uP>!

[TurboBanshee_kid]

I will buy just the bike from you with no engine for $2000 and i will put my banshee engine in it.  Get back to me