Big Prob Need Answers

1640 Views 28 Replies 12 Participants Last post by cmat, Mar 18, 2009

xxasilaydyingxx

Discussion Starter · Mar 11, 2009

3

I have a fresh motor in my yfz about 40hrs on her crank,piston,cyl, and heads by ttm so today I went to check my valves and found the intake cam and cam/cradles scored like it ran out of oil see pics. I dont baby my bike in anyway but am always 110% on top of maintenance. I drained the oil and ran a magnet threw it and came up with no metal shavings bolts were tight on the cam tower, it had plenty of oil and, the exhaust cam/cradle is perfect. So I have no idea how this happened and am about too lose it :angryfire: because my head I just spent 400$$$ on 2 months ago is trash
PLEASE HELP ME FIGURE THIS OUT racing starts in 14 days

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YFZ450 #69

· #2 · Mar 11, 2009

QUOTE (05 YFZ450#117 @ Mar 11 2009, 03:34 PM) index.php?act=findpost&pid=756594

bolts were tight on the cam tower[/b]

how tight?

it looks like they were too tight...and that oil is pretty dirty?

YFZER359

· #3 · Mar 11, 2009

i'd have to agree with... adam is it? Mr. Captain Obvious? lol

but yea, 7.5 FT. LBS. aint a whole lot, and your oil looks REALLY dark

989tommyboy

· #4 · Mar 11, 2009

QUOTE (05 YFZ450#117 @ Mar 11 2009, 04:34 PM) index.php?act=findpost&pid=756594

I have a fresh motor in my yfz about 40hrs on her crank,piston,cyl, and heads by ttm so today I went to check my valves and found the intake cam and cam/cradles scored like it ran out of oil see pics. I dont baby my bike in anyway but am always 110% on top of maintenance. I drained the oil and ran a magnet threw it and came up with no metal shavings bolts were tight on the cam tower, it had plenty of oil and, the exhaust cam/cradle is perfect. So I have no idea how this happened and am about too lose it :angryfire: because my head I just spent 400$$$ on 2 months ago is trash
PLEASE HELP ME FIGURE THIS OUT racing starts in 14 days

[/b]

did you send your head to ttm and get yours back or did you just swap heads.

xxasilaydyingxx

Discussion Starter · #5 · Mar 11, 2009

the bolts were all torqued to 7.5 with a snap on tw when I put the motor together and the oil was changed 4 rides ago it looks dark in the picture because there was no light

YFZ450 #69

· #6 · Mar 12, 2009

something doesnt add up then...

when you torque them, do you do a final check to see if you can spin the cams by hand? I've come across several torqued cam caps that wont allow the cams to spin freely.

7.2ft lb is the spec but .3 of a difference wont burn your head up like that. can you check the cams for runout?

at the end of the day, you need to try and clean those journals up as best you can...gently.
are there any gouges in them or is it just visual marks?

Terse

· #7 · Mar 12, 2009

What kind of torque wrench did you use?

SyKo450

· #8 · Mar 12, 2009

Says Snap-On

I wonder if he confused lb/ft with the meter side of the tq?

Terse

· #9 · Mar 12, 2009

I'm wanting to know how accurate the 7.2lbs is/ was. Most ft lb wrenches only go to 10lbs, and aren't very accurate at 10lbs... much less anything less then that.

DOZER520

· #10 · Mar 12, 2009

BEEN THERE DONE THAT.
i used a foot pound wrench and between that and the fact that i didn't hand check them to see if they moving freely i had the same thing happen.

i am actually repairing mine and i'm confident i can use the head again. my journals actually got "tighter" at 3oclock and 9oclock. i used some 320,400,600 sand paper and very carefully got the journals cleaned up to the point where i can get my cams torqued again and have them spin freely. it was a very tedious process but i did it. i have to replace 2 guides and some valves, but fortunately it's usable- i thought it was trash.

xxasilaydyingxx

Discussion Starter · #11 · Mar 12, 2009

It was a snap on in lb/nm torque wrench and went to 20nm aprox. 15ft lbs The bolts ex/in were torqued down to 10 nm which is spec. I didnt get any numbers confused i have rebuilt a number of these motors and know how to use a torque wrench the exhaust has no damage and was set at the same spec. the engine ran strong with loads of power after the rebuild but about a week ago it was a little harder to start like the battery was going dead or there was a strain on the motor

SyKo450

· #12 · Mar 12, 2009

Clean the oil tank screen often?

xxasilaydyingxx

Discussion Starter · #13 · Mar 12, 2009

Thats the thing I just did a full rebuild all lines the tank the tank screen and the screen in the crank case were cleaned Thats why I dont know what to make of this

SyKo450

· #14 · Mar 12, 2009

Clean your parts with a clean rag before setting them in place?

sidewinder

· #15 · Mar 12, 2009

How many times have you changed the oil since the rebuild? Just the once?

xxasilaydyingxx

Discussion Starter · #16 · Mar 12, 2009

parts were cleaned with break clean and blown out with compressed air and i have changed the oil three times cense the rebuild

Joester

· #17 · Mar 12, 2009

those cam DO looked overtightened, i dont know if it was you or the wrench, but i think something went wrong when you were tightening it. It only takes a little more to make em lock up. did you spin them by hand?

xxasilaydyingxx

Discussion Starter · #18 · Mar 12, 2009

no but i turned the motor over via the flywheel but what i dont understand about your statement is the same wrench at the same setting at the same time was used to torque the ex cam down and that cam and cradle is perfect no damage.

sidewinder

· #19 · Mar 12, 2009

You didn't lose the camshaft clip did you? Stupid question but have to ask.

Joester

· #20 · Mar 12, 2009

i bet its deep inside somewhere... lol jk.

i know mine was sketchy close to getting in.... all the way... it was scary, and traumatizing.

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