The DESTRUCTION pics

[jakemax04]

http://i1178.photobucket.com/albums/...4/IMG_0171.jpg
http://i1178.photobucket.com/albums/...4/IMG_0170.jpg
http://i1178.photobucket.com/albums/...4/IMG_0173.jpg

Guys this is my poor poor yfzr, was just wondering what this looks like to some engine builders out there. if anyone thinks they know what causes this please let me know. i ran an intake cam for awhile without the proper tune. maybe it ran lean for too long but how does that explain the perfect indention of the valves into the piston. The valves had to float to cause this so im not sure how to pinpoint this problem. im sending my motor off to a builder so hopefully this wont happen again but id like to know exactly what caused this.

[misdirected]

man i thought mine was bad when it happend but your is by far worse your going to need a new head piston cylinder of course but it happends when improper valve adjustments are done or the cam chain was old if the tensor was bad sorry for your luck just build it better and faster is all you can do

[cpenalty217]

Wow that is definatley the worst case I have ever seen. Sucks ass man but I agree with misdirected all you can do is build it better and faster!

[nickmell]

O my sweet jesus, I am so so sorry that picture makes my wana cry a little. I kinds want to sell my 450 and get a 2 strole now.

[jakemax04]

haha no worries it will be back stronger, its just something didnt mesh right. im not sure what but i will find out and it shouldnt happen again. especially since im letting a pro build it.

[climb-101]

tough to tell what happended from pics but if i was guessing i would say a valve broke and drop in there. how long did you run it while it was making funny sounds. looks like a while

[jakemax04]

nope no funny noises, it came to a sudden grinding halt in fifth gear

[bbcmudtruck]

WOW! Thats pretty impressive! Whos going to build your next motor? Any plans on what you will build yet?

[Narmasil]

for changing the cam the valves shouldnt start float. i have also another intake and its no problem. Perhaps you got some debri in your intake? if you ride in sand and such its important to change air filter pretty often. A friend did about the same you did and he got sand in the engine.

Do the camchain look damaged? another friend got his camchain damaged so it would ride on top of the cogs on the cams and made a nice buffét of the whole stuff... arrrgh.

Is your camchain tensioner alright? maby the spring inside or so is damaged so it came lose and started jumping cogs and then valves went into the piston. By the looks of it your timing has somehow came all wrong with the piston contra cams

[thecoyfish]

Wow!!! I did the same thing on my 04. I found out that I ran low on oil or something like that and the cam girded on the head and stuck the vavles open, Bad deal. What are your plans for the new motor???

[buddah]

Wow!!!! I chunked a piston due to detonation on my Raptor and it didn't cause near the damage your's is showing. Man, that's just nasty. My guess would be a broken valve or the motor was running very lean. A hole in the piston, like your's is showing, is usually caused from a lean condition............. Good luck on the rebuild.

BTW, did you ever notice the motor pinging under a load?

[jakemax04]

for changing the cam the valves shouldnt start float. i have also another intake and its no problem. Perhaps you got some debri in your intake? if you ride in sand and such its important to change air filter pretty often. A friend did about the same you did and he got sand in the engine.

Do the camchain look damaged? another friend got his camchain damaged so it would ride on top of the cogs on the cams and made a nice buffét of the whole stuff... arrrgh.

Is your camchain tensioner alright? maby the spring inside or so is damaged so it came lose and started jumping cogs and then valves went into the piston. By the looks of it your timing has somehow came all wrong with the piston contra cams

i checked the intake when i took everything apart and was clean as a whistle, but the engine side of the throttle body had some debri probly from the explosion of valves in the head. as far as the timing jump that does make sense cause of the perfect indention of the valves in the piston. I believe the hole in the middle was caused from the broken off valves getting crunched in between the spark plug. my plug was crushed also. i checked the tensioner when i took it off and when it came out it extended all the way and i tried pushing it in by hand and it wouldnt go. so if it did jump timing im still not sure how.

WOW! Thats pretty impressive! Whos going to build your next motor? Any plans on what you will build yet?

im planning on sending it to williamsatvperformance, and the plans are:
Big bore
port and polish
+1valves
stronger valve springs
JE 12.1 or 13.1 compression(not sure yet)
throttle body bore
web cams
carillo rod(for piece of mind)

[jakemax04]

skip the +1 valves.... the aftermarket steel valves dont last as long as the oem yamaha valves... and you need to buy springs too...

plus, the aftermarket titanium ones have a terible flow profile....


oem yamaha is an awesome valvetrain

thanks for the tip, i will keep that in mind and yes im goin with titanium.

[YFZ450~BENCE]

wow thats terrible!! i doubt there should be float from just stage 1 hotcam.

['05 YFZ Racer]

Well theres yah problem....

[Haas33]

that makes me glad that i decided to rebuild my motor this winter

[funyun]

Originally Posted by mixxer

dont do it!! im telling you something BIG here!!

the valve profile makes a much bigger difference to flow than does a small change in diameter....

yamaha did a buttload of development to make the 5-valve as right as possible from the factory in the valvetrain dept...and its for real...!! the stock valvetrain is the best the dirt world has EVER had....

the aftermarket ti valves that are most common have no more design in them than glueing a casino chip on a popsicle stick!! terrible low to mid lift flow...which is one of the strong points of multi valve heads... ESPECIALLY the 5-valve

the aftermarket steel valbes have copied the excellent yamaha oem profile.... but they need heavy springs and done wear as well....

get close up pics of the valves and post them up... i swear you will be making huge mistake if you dont....

power comes from the profile and the airflow enhancements it can make...not the material of the valve....

Which aftermarket TI valves are you refering too? Seems like there are a few different ones out there. Some places have custom Ti valves too.

[funyun]

You are buying a new motor im assuming?

[kb motorsports]

Originally Posted by jakemax04

http://i1178.photobucket.com/albums/...4/IMG_0171.jpg
http://i1178.photobucket.com/albums/...4/IMG_0170.jpg
http://i1178.photobucket.com/albums/...4/IMG_0173.jpg

Guys this is my poor poor yfzr, was just wondering what this looks like to some engine builders out there. if anyone thinks they know what causes this please let me know. i ran an intake cam for awhile without the proper tune. maybe it ran lean for too long but how does that explain the perfect indention of the valves into the piston. The valves had to float to cause this so im not sure how to pinpoint this problem. im sending my motor off to a builder so hopefully this wont happen again but id like to know exactly what caused this.

Ouch! Harsh art work!

[jakemax04]

You are buying a new motor im assuming?

ya pretty much, it will be from the rod up.

And thx for ur help mixxer, i will be going stock ti valves. i just hope this never happens again. i can deal with it if it had big time power and had a lot of hours on it, but the bike was fairly new and had maybe 3 to 4 trips to the sand dunes, and a few joy rides elsewhere. the oil was changed more often than need be and i thought everything was good. basic mods and it grenaded. it sucks but it happens i guess. all it takes is money to bring it back better!