'08 450 with 47 hours = locked up :(

[2strokenut]

As I have said before, there was no indication from the motor that a valve was suspect. It ran perfectly. If the valve was out of adjustment to the point of it causing a major failure, then I would have had some other indication, no?

From my experience, thats the problem with thumpers. I can feel a loss of power when I need a top end on my 250t but with a 4t they will run good until they go boom. Very sneaky. This was the problem every one of my buddies who bought 4ts had when they came out. They grew accustomed to "feeling" when they needed a top end but more often then not their 250fs or 450s went boom when the bike started fine and ran fine:excuseme:

I dont mean to start arguing but if I had a thumper again I would check the valves religiously every 5-10 hours. But thats just me. Hope that ebay head works out, that will save ya a bundle.

[2strokenut]

if an XR drops a valve, do you think it will be a simple and cheap fix?

Of course it would be cheap, I would throw it away or part it out:busted:

JK that was uncalled for. I could fix it for cheaper than a yzf450 most likely:excuseme:

[alleycat50]

From my experience, thats the problem with thumpers. I can feel a loss of power when I need a top end on my 250t but with a 4t they will run good until they go boom. Very sneaky. This was the problem every one of my buddies who bought 4ts had when they came out. They grew accustomed to "feeling" when they needed a top end but more often then not their 250fs or 450s went boom when the bike started fine and ran fine:excuseme:

I dont mean to start arguing but if I had a thumper again I would check the valves religiously every 5-10 hours. But thats just me. Hope that ebay head works out, that will save ya a bundle.

I spoke with the local Yama Mechanic.(good friend of mine too) He said that he checked the valves after about 10hrs of riding on a new bike(450) and there was one tight one.Possibly just a fluke, but this is what he recommends.I do all of my own work, so he is not just saying this to get $$$.It is not uncommon on a new bike.After the first 10 or so Hrs,the average rider could get away with once a season(6months).

Just what he says.He has been doing this ever since the YZ400's,I trust him.

[swaldrop]

If this head will fit, it will save you a little money.

http://cgi.ebay.com/ebaymotors/YZ450F-COMPLETE-HEAD_W0QQcmdZViewItemQQcategoryZ35595QQihZ014QQitemZ330239028389QQrdZ1QQsspagenameZWDVW

Just found out that the head is for an '04, so no go. I'll keep looking though.

Thanks again

[grayracer513]

Just because a few people have gone so long on stock valves doesnt make it smart for someone to go 47 hours without at least checking the vlaves:excuseme: I thought my point was pretty clear.

Like I said above, going that long without checking to see if clearances were in spec is not smart. People make the yami 450 out to be some sort of blue XR, which is not the case.

Well, you got me thinking, you know, and my '06 was out there in the shop with the tank off, anyway, and being that it has about 75 hours on it, and no clearance check since it had about 15, it needed to be checked, by your standards. So I did.

Now that I have checked them, what am I supposed to do with the fact that it doesn't need an adjustment, and the clearance hasn't changed in the last 60 hours? Will I be less likely to drop a valve now that I have done little more than get some fresh air under the cover?

Only one form of neglect can lead to a valve head breaking off, and that is to continue running an engine with one or more valves that has needed more than one adjustment, or that has been shimmed more than .10mm from its original size. Obviously, this does not apply here. If a YZF valve simply breaks at the stem/head joint under any other circumstance, that joint was defective, simple as that.

Your personal campaign against 4-strokes on the basis of how expensive they are to repair is interesting, but adds nothing to the subject of this thread, unless you count "I told you so" as being pertinent to handling the repairs of this gentleman's broken engine. Calling any of us "tards" is not acceptable.

[corndog67]

As for lapping titanium valves, I would check with the manufacturer of the valves, not Yamaha. I work in a top fuel cylinder head shop, I'll ask the valve job guys tomorrow what they think (I'm in the machining side of things), and post back.

One of my old co-workers, an A rider and the fastest guy in the shop, had a 99 or 2000 WR, and after the initial break in adjustment, didn't need an adjustment for 5 years. That is why I bought an 06 YZ450. Because they are rumored to be bulletproof. I hope that turns out to be the case.

[motoclay]

First off haha, WHAT TEAM/SHOP DO U WORK FOR CORNDOG!!!???

Second, i dont care what valve it is, material its made of or what, it needs to be lapped to properly seal, bottom line. I mean, yeah, wear to fit it will get better with time, and yada yada yada. I dont want to hijack this guys thread, he has a serious blown up 450, and its keepin him off the track, i am giving what little knowledge i have with engines and performance, and cylinder/head seal is critical to maximizing your engines potential, thats why you put new rings in every so often, to keept he SEAL!!!

[grayracer513]

My position remains unchanged.

[JSanfilippo]

You could add "to lap or not to lap titanium valves" to the list of oil, religion, smoker vs. thumper, coolant, and other "fight" theads. ?

I suppose lapping a TI valve will give you a marginally better seal...but that valve is only going to last 5 hours...if that

I'll say this! I'll beleive those with knowledge, experience, credibility over some know it all blowhard

[bigred455]

I had a thread the topic was 07 left intake tight from factory,to refresh everyone. This is my 2nd 07 450 NEW ,just like the first one ,the right intake was .003 from the factory. I did not even start up both bikes,both stock shims were 184,I just through a 180 shim and I was right on .004. What I am getting at is, in mass production they do not have time to shim check shim check every bike,they get a average and go with that. Yamaha likes to shim on the tight side which I am all for,but the left intake is a little too tight from the factory.

[Lowedog]

http://www.zanottimotor.com/ Best prices I have found on OEM Yamaha parts.

-Lowedog

[matt4x4]

/BEGIN INTERMISSION

Ok, let me shed some light on the whole valve lapping issue at hand here.

First off, you do not lap the valves, you lap the SEAT.

BUT (and it's a BIG but)

You are supposed to use a valve lapping tool/disk which is essentially a cast iron tool shaped EXACTLY the same as the valve, NOT the valve itself - this is the big problem here and after 9 pages, you'd think SOMEONE would have caught that.

After cutting the seats you are supposed to be grinding the seat in, this process usually leaves irregularities that are just larger than what is acceptable, this is when you lap the valve seats, however, NOT using your valves!!!

Oh, by the way, grinding in is pretty much lapping except that you work your way from a rougher to a finer compound, never going quite as fine as the compound used to lap valves.

Lapping was left to the installer since the guy in the machine shop only machines/finishes so far.

maybe valve manufacturers should ship a lapping tool in each set of Ti-valves to stop the confusion.

Back in the pre ti-valve days when everything was steel, most mechanics used the actual valve they were putting into that particular valve seat - what it did is mate both surfaces of the final product installed for an even better fit, if you had 4 valves you used all 4 valves to do the lapping, but in the day of Ti-Valves, you DO NOT use the valves as Grayracer has been trying to tell you for a number of pages.

/END INTERMISSION

[grayracer513]

What I am getting at is, in mass production they do not have time to shim check shim check every bike,they get a average and go with that.

This is incorrect. Each and every head is checked and each valve is individually shimmed. Note that every valve in every YZF head will have a different shim, and that those shims are in .01mm increments. They don't get that way by taking an average.

What does happen in mass production situations like this is that these measurements are made using jig fixtures that speed up the process, and usually do more than one measurement at a time. The accuracy of these needs to be periodically checked, and if the jig gets tweaked, the factory can easily produce a large number of mis-adjusted parts before the error is discovered. Not something that I expect from any Japanese manufacturer, but when you see multiple identical defects in a series of parts, this kind of thing is generally the cause.

[MotoGoalie]

First off haha, WHAT TEAM/SHOP DO U WORK FOR CORNDOG!!!???

Second, i dont care what valve it is, material its made of or what, it needs to be lapped to properly seal, bottom line. I mean, yeah, wear to fit it will get better with time, and yada yada yada. !!

Do a search for some punters that lapped a WR450 set of valves using the valves as a lapping tool, a few years ago, and you'll see what the real *benefits* of that dubious project is worth.

This isnt a 2v V8 you're working on here:bonk:

[motoclay]

LOL, ok ok, i give i give, but, for the record, I DID LAP MY 450 VALVES THE OLD FASHION WAY!!!!

And guess what, the seal was spot on, and the performance was excellent, i will admit, the valves were SS, but, i have never heard of the Ti argument before. So i admit my stupidity here. There is no need for name calling, i never did that to ne of you. IM not a PUNTER, or a KNOW IT ALL BLOWHARD, or ne thing else for that matter. I am a man with experience with the EXACT issue this gentleman is dealing with and i wanted to put in my OPINIONS!!!! I do understand the engines in these machines very very well, i knew exactly what happened when he described his issue, i knew what the pics looked like before they were here, again, EXPERIENCE is where this is coming from. IM not some hillbilly that likes to stir the sheet, i appologize for showing my stupidity on Ti valves.

[corndog67]

OK, check this out. One of my direct supervisors is the top guy in Top Fuel cylinder heads in the country, actually all cylinder heads and I trust his opinion very much. Valves like Manley or Stealth Titanium for the top fuel application are not coated and are lapped in. My boss bought a set of Kibbles and lapped them in on his CRF450 and was adjusting them weekly, they were sinking in the seats. They are hardfaced at about .001" thickness on the faces of the valves, and he had gone through the hardfacing, and they started wearing rapidly. So, lesson learned, he suggests not lapping them in, it doesn't take long to go through .001" with some of the more aggressive lapping compounds.

Robert

[grayracer513]

Top fuel cars run for a total of perhaps 20 minutes during the course of a weekend meet, and in that time, they are rebuilt at least ten times. They are interesting, but not pertinent.

The hard coating of a Ti valve as used in a YZF is far thinner than the hardening on a SS valve (0.0001", not 0.001"), and the underlying base metal is not as hard as steel to begin with. The coating (which is actually a ceramic) is so thin because it is so hard (estimated at more than 85 on the Rockwell C scale, which is essentially out of range at that level, and no longer very useful) that it cannot be machined. So, the valve is finished and the coating applied in a thin enough layer that irregularities in coating will not significantly alter the trueness of the surfaces.

Don't lap them

[erik981]

i had the same problem with my 07 450. pull the valve cover and check the timing, i have had two cam chain tensioners go bad and cause the chain to jump teeth on the cam gears. so check the exhaust cam becausse if it jumped teeth it would cause the auto decompresser pin to not engage.

[Scspringer912]

BIg Steve.. it's springer

First off nice smiley face in your title ha ha Anyway after reading all of this i think about 3 people actually know what they are talking about. Love the guys that post my bike has 1 million hours on my bike no problems. LIke this is a brag about how many hours your bike has and how slow you are so you can put another million hours on it. Anyway this whole situation sucks, I hope this or anything with bikes breaking never happens to you or me ever!!! I was set on getting 09 after my year off to relax but now i am freaked out about getting another bike because of YOU.. fix it cheap and trade it in and not on a 250F.. somebody please tell him 450's almost 99% of the time are more reliable.

how's WILLLLL IEEE He still kicking people out of A- B practice for not keeping steady lap times... lol Then kicking us out of C class back to A-B for doing all the jumps. lets get 09 HOnda's

[swaldrop]

BIg Steve.. it's springer

First off nice smiley face in your title ha ha Anyway after reading all of this i think about 3 people actually know what they are talking about. Love the guys that post my bike has 1 million hours on my bike no problems. LIke this is a brag about how many hours your bike has and how slow you are so you can put another million hours on it. Anyway this whole situation sucks, I hope this or anything with bikes breaking never happens to you or me ever!!! I was set on getting 09 after my year off to relax but now i am freaked out about getting another bike because of YOU.. fix it cheap and trade it in and not on a 250F.. somebody please tell him 450's almost 99% of the time are more reliable.

how's WILLLLL IEEE He still kicking people out of A- B practice for not keeping steady lap times... lol Then kicking us out of C class back to A-B for doing all the jumps. lets get 09 HOnda's

Oh man... I've already made my decision... I am going to get a 250F. I may hang on to the 450 and take my time getting it fixed to save some money, but the next time I'm on the track I'll be YZ250F'n. No Honda's...

Willie's gone. He came back and helped out for this last series we had, but I don't think he's going to come back to work practice days. He still doesn't have any shoes though.