Has Anyone put a topend in their 06 yet?


31 replies to this topic
  • sacfelix

Posted February 28, 2009 - 02:02 PM

#21

I race my 06 through the desert doing the MRANN series. I had to change the timing chain at 60hrs but the rest of the motor is solid with no valve movement. I now have 86hrs and the piston still looks great and valves even better.

  • grayracer513

Posted February 28, 2009 - 02:16 PM

#22

I guess that is why every one else in the industry is using wire clips. This was a low hour original engine that dropped the clip into the lowerend and when the pin slid far enough out it broke the piston, rod, cases , balance shaft and cylinder skirt. So much for the engine builder. Yamaha built this one. This is the third one I have seen fail. Just a warning for those of you who think they will last forever, pull it apart and check it once in awhile. It is a race bike not a daily driver.

Everyone else? Yamaha is the only one? Don't say stuff that's so obviously false that it erodes your credibility.

In over 40 years of assembling engines, I have never had a single wrist pin clip fail in any engine I put together, regardless of type or application. The only ones I've seen fail where I was able to oversee the tear down had the remaining clip incorrectly oriented.

  • VB_Racing

Posted February 28, 2009 - 02:57 PM

#23

I don't know how your bike could need all that unless you are not oiling your air filter properly. I changed my piston at 60 hours and it looked great, couldn't tell it had more than 5 minutes of run time on it. My valves have never moved either. I am an A class MX racer and spend a lot of time wide open.


I use pre oiled filters, the same filters I use on all my bikes, and do change them frequently. My pistons look OK, until you put a mic on them( I work as an auto tech, and a machinist). The chain is kinked, and the valves do not pass a vacuum test. Have the valves moved, no, but they don't seal as well as they should.I think in all fairness, the ice racing is extremely hard on the motor. I needed a crankshaft on my 07 Honda CRF450 at 25 or so hours(and the piston was in poor condition).
That being said, Most guys in our area do not get the hours you guys are claiming, I want to understand why, the cold??And to throw another wrench in the works, I pulled my 03 WR450 down last year, because I didn't know how many hours were on it(I purchased it used)and it was like new yet with at least 30 hours that I put on it. I use the same air filters, and actually change the oil less, yet it stays fresher longer. I don't get it

Dave

  • KJ790

Posted February 28, 2009 - 03:53 PM

#24

I use pre oiled filters, the same filters I use on all my bikes, and do change them frequently. My pistons look OK, until you put a mic on them( I work as an auto tech, and a machinist). The chain is kinked, and the valves do not pass a vacuum test. Have the valves moved, no, but they don't seal as well as they should.I think in all fairness, the ice racing is extremely hard on the motor. I needed a crankshaft on my 07 Honda CRF450 at 25 or so hours(and the piston was in poor condition).
That being said, Most guys in our area do not get the hours you guys are claiming, I want to understand why, the cold??And to throw another wrench in the works, I pulled my 03 WR450 down last year, because I didn't know how many hours were on it(I purchased it used)and it was like new yet with at least 30 hours that I put on it. I use the same air filters, and actually change the oil less, yet it stays fresher longer. I don't get it

Dave


I've never seen a piston that measured out under spec that I would say looked OK. I haven't heard of many (if any) people having problems with cam chains kinking, especially since the automatic chain adjuster keeps them under quite a bit of tension. Maybe you have a problem with the tensioner. Yamaha's cam chain issues almost always revolve around it stretching and taking the teeth off of the sprocket that is cut in the end of the crank, which requires a new crank to fix. For $10 it is easy to change the cam chain every 50 hours or so to save the gear on the crank, but there really is no reason to need a chain before that unless there is something else wrong with your engine. Which valves are leaking, intake, exhaust, or both? Temperature shouldn't make much of a difference on engine longevity as long as you warm the engine up properly and make sure the jetting is correct. The WR450F and the YZ450F have essentially the same engine (plus some extras on the WR), so they should wear out about equally if they are ridden the same in the same conditions with the same maintenance.

  • grayracer513

Posted February 28, 2009 - 05:35 PM

#25

I haven't heard of many (if any) people having problems with cam chains kinking, especially since the automatic chain adjuster keeps them under quite a bit of tension. Maybe you have a problem with the tensioner.

That's actually been reported here a few times. It usually does turn out to be a problem with a failed or damaged tensioner, but it's very rare on the '05 or earlier models. The redesigned tensioner that came out in '06 seems to be a little less robust.

  • VB_Racing

Posted February 28, 2009 - 09:13 PM

#26

I've never seen a piston that measured out under spec that I would say looked OK. I haven't heard of many (if any) people having problems with cam chains kinking, especially since the automatic chain adjuster keeps them under quite a bit of tension. Maybe you have a problem with the tensioner. Yamaha's cam chain issues almost always revolve around it stretching and taking the teeth off of the sprocket that is cut in the end of the crank, which requires a new crank to fix. For $10 it is easy to change the cam chain every 50 hours or so to save the gear on the crank, but there really is no reason to need a chain before that unless there is something else wrong with your engine. Which valves are leaking, intake, exhaust, or both? Temperature shouldn't make much of a difference on engine longevity as long as you warm the engine up properly and make sure the jetting is correct. The WR450F and the YZ450F have essentially the same engine (plus some extras on the WR), so they should wear out about equally if they are ridden the same in the same conditions with the same maintenance.


This is where you and I differ,...I am not trying to start a pissing match so don't take this as such, but here goes...
A little background on myself. I have been an autmotive technician, as wel as a warranty inspector for for the past 22 years. I have owned my own motorcycle repair business until just recently, when the economy forced me back into the automotive service and machining field.
When I take a motor apart, I look for obvious wear, and not so obvious wear. Just because a piston looks OK, that doesn't mean that it will measure out to spec, I will go to the safe side and replace a part rather than just chance it because it "looks" OK. If a piston skirt measures small, I will replace it, if the bore measures big, I will replace it. If the timing chain starts to look kinked, I will replace it, not take a chance that it will be OK. I have put together several of these motors for several different customers, and have always found that the chains will start to kink up around the 30 hour mark. 15 bucks is chaep insurance. I will vacuum check the cylinder head to make sure that the valves have a good seal. This involves pulling a vacuum on the intake and exhaust port, and measuring vacuum loss. If they leak , they leak, it doesn't matter what the valve specs were. When I cut, or polish the seats, and install new valves, tehy will pass the vacuum test. Minor, maybe, but why take the chance.
I think this is more a product of ice racing than Motox, ice racing is extremely hard on the bikes, because of the stress on every part of the motor. You have to remember that these bikes will have more traction on the ice, than you could ever achieve on the pavement, let alone the dirt. THis may be the key, but I am just curious as to why I don't see the service life out of these bikes that some of you have. I do agree that the Yamaha is a tough motor, but I just fixed up a motor for a friend that needed 1400 dollars worth of parts , because they were trying to get the service life some of you are getting.
I am not calling anybody out, or disbelieving, I just want to get to the reason why I am not seeing it.Make sense?

Dave

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  • KJ790

Posted February 28, 2009 - 09:44 PM

#27

This is where you and I differ,...I am not trying to start a pissing match so don't take this as such, but here goes...
A little background on myself. I have been an autmotive technician, as wel as a warranty inspector for for the past 22 years. I have owned my own motorcycle repair business until just recently, when the economy forced me back into the automotive service and machining field.
When I take a motor apart, I look for obvious wear, and not so obvious wear. Just because a piston looks OK, that doesn't mean that it will measure out to spec, I will go to the safe side and replace a part rather than just chance it because it "looks" OK. If a piston skirt measures small, I will replace it, if the bore measures big, I will replace it. If the timing chain starts to look kinked, I will replace it, not take a chance that it will be OK. I have put together several of these motors for several different customers, and have always found that the chains will start to kink up around the 30 hour mark. 15 bucks is chaep insurance. I will vacuum check the cylinder head to make sure that the valves have a good seal. This involves pulling a vacuum on the intake and exhaust port, and measuring vacuum loss. If they leak , they leak, it doesn't matter what the valve specs were. When I cut, or polish the seats, and install new valves, tehy will pass the vacuum test. Minor, maybe, but why take the chance.
I think this is more a product of ice racing than Motox, ice racing is extremely hard on the bikes, because of the stress on every part of the motor. You have to remember that these bikes will have more traction on the ice, than you could ever achieve on the pavement, let alone the dirt. THis may be the key, but I am just curious as to why I don't see the service life out of these bikes that some of you have. I do agree that the Yamaha is a tough motor, but I just fixed up a motor for a friend that needed 1400 dollars worth of parts , because they were trying to get the service life some of you are getting.
I am not calling anybody out, or disbelieving, I just want to get to the reason why I am not seeing it.Make sense?

Dave


You and I don't differ as much as you think, but I have not had any of the problems that you seem to be having. Perhaps it is the extra traction of ice racing, I don't know. I personally haven't done any ice racing, but my father raced on ice quite a bit back in the 80's, he even ran a few pro races. Next time I talk to him I'll have to ask if he noticed a difference in engine life between his winter race bikes and his summer ones (he ran MX in the summer), however things have changed a lot in the last 25 years.

Personally, if I remove a part like a piston, I replace it. That's just how I am, regardless of how few of hours are on it or what it measures out to. I've had 5 Yamaha four strokes. At first I changed pistons every 20 hours, and they always measured in spec, but I changed them anyways. Then I kept hearing about guys getting 100 hours on pistons and what not, so I started stretching it out. I still check my valves every 10 hours on my hour meter, and have never had a cam chain kink. If your tensioner is working properly, a cam chain should never kink.

I now replace my pistons every 55-60 hours on my hour meter, and they still measure within spec. Unless you are having an oil issue, or are getting dirt in the engine, a piston should not wear out that quickly, no matter how much traction you are getting. Everyone knows that owner's manuals grossly underestimate the time intervals for part inspection and replacement to cover the manufacturer's butt, but the Yamaha owner's manual even says to inspect the piston around every 20-25 hours and replace when it is out of spec. If I were a person that put parts back in to the engine if they were still in spec, who's to say how many hours I would get on a piston since they are still in spec at 60 hours.

I'm not trying to start a pissing match, I'm trying to help you find out why you can't get any life out of your engines.

  • wellsy1

Posted February 28, 2009 - 11:02 PM

#28

I said earlier I got 100 hours before I did my first top end in my 06 YZ450f. I replaced the piston(wisco), Kibblewhite ss valves, spring, seat, you name it I replaced it. Sent it to a machine shop (mongoose machine) in vancouver,B.C. in Canada. Put it back together my self. Had to adjust my intakes valves once. Able to get another another 103 hours(203 total running hours on two pistons, and valve upgrade) Got a fith gear tranny issue developing. Going to take care of that. Other than that its a soild motor. I'm running 94octane Chevron. And I ride her hard. But i dont race. I ride every chance i get.

  • Joe_Jet

Posted March 01, 2009 - 01:48 AM

#29

my 07 had 147 hrs of SoCal mx on it when I sold it. never touched the top end or did a valve adjust. it was still starting on the first kick and pulling holeshots!

  • grayracer513

Posted March 01, 2009 - 10:16 AM

#30

...(I) have always found that the chains will start to kink up around the 30 hour mark. ...I will vacuum check the cylinder head to make sure that the valves have a good seal. ... If they leak , they leak, it doesn't matter what the valve specs were. When I cut, or polish the seats, and install new valves, tehy will pass the vacuum test. Minor, maybe, but why take the chance. ... I am just curious as to why I don't see the service life out of these bikes that some of you have.

Well, we could compare credentials, I suppose, but that wouldn't accomplish much, would it?

There may or may not be any merit to the concept that ice racing produces heavier loads or introduces greater wear on an engine than MX. It's likely that there is something to the fact that ice racing, half-mile, mile tracks, SM and road racing all include longer high gear, full throttle pulls than MX does. And, I would argue that MX is likely to be tougher on the transmission and drive train than any of these other forms of racing are, but that's not the point here.

Top end wear is sensitive to the load borne by the assembly, so your piston wear could come from there. The valve seats and timing chain are not affected by applied load, however, only operating speed, so that takes the traction question off the table.

My son and I run up between 70 and 100 hours per year of mixed riding on our bikes, most of it pretty hard time. Not like spending every day on a mile track, but tough all the same. I replace our timing chains every 12-15 months, and except for the first one I replaced in his 250F, which was past due for replacement, none of them have even shown significant wear. None of them have shown any signs of kinking whatsoever. I have found a kinked chain in another bike at an unusually early point, but the tensioner on that one was clearly faulty.

I took the top off my son's bike to replace a head gasket late last fall, when it was over two years old, and the piston did not look good, it looked new. Actual piston/bore clearance was excellent, and a solvent test of the head showed no seepage. Now that it has new rings and is broken in, a leak down shows excellent numbers. I don't know how you are measuring your pistons, but I'm sure you know the importance of measuring them in the correct spot, because they are not cylindrical. Have you tried measuring the clearance, or only the piston size?

And, since your experience has not been as good as some others, have you considered your oil selection? Perhaps you might send off a used sample of whatever you've been using for a UOA, and see what that says.

It could just be the severity of the use you're putting the engine to; as I said, you do have those prolonged straightaway pulls, and such. Hard to say.

  • Kasjok

Posted March 01, 2009 - 10:46 AM

#31

This chain is from 08 machine with 80 hours on it. It has this one small kink in it that is rather stiff.
Posted Image

  • VB_Racing

Posted March 01, 2009 - 11:49 AM

#32

Well, we could compare credentials, I suppose, but that wouldn't accomplish much, would it?

There may or may not be any merit to the concept that ice racing produces heavier loads or introduces greater wear on an engine than MX. It's likely that there is something to the fact that ice racing, half-mile, mile tracks, SM and road racing all include longer high gear, full throttle pulls than MX does. And, I would argue that MX is likely to be tougher on the transmission and drive train than any of these other forms of racing are, but that's not the point here.

Top end wear is sensitive to the load borne by the assembly, so your piston wear could come from there. The valve seats and timing chain are not affected by applied load, however, only operating speed, so that takes the traction question off the table.

My son and I run up between 70 and 100 hours per year of mixed riding on our bikes, most of it pretty hard time. Not like spending every day on a mile track, but tough all the same. I replace our timing chains every 12-15 months, and except for the first one I replaced in his 250F, which was past due for replacement, none of them have even shown significant wear. None of them have shown any signs of kinking whatsoever. I have found a kinked chain in another bike at an unusually early point, but the tensioner on that one was clearly faulty.

I took the top off my son's bike to replace a head gasket late last fall, when it was over two years old, and the piston did not look good, it looked new. Actual piston/bore clearance was excellent, and a solvent test of the head showed no seepage. Now that it has new rings and is broken in, a leak down shows excellent numbers. I don't know how you are measuring your pistons, but I'm sure you know the importance of measuring them in the correct spot, because they are not cylindrical. Have you tried measuring the clearance, or only the piston size?

And, since your experience has not been as good as some others, have you considered your oil selection? Perhaps you might send off a used sample of whatever you've been using for a UOA, and see what that says.

It could just be the severity of the use you're putting the engine to; as I said, you do have those prolonged straightaway pulls, and such. Hard to say.


First off , not trying to compare credentials, because as you say, it doesn't accomplish much, Just trying to give you my experience level, that's all.
I have to believe seepage in a solvent test would not show as well as a vacuum test, but I have used the same method before with very different results. In the most recent example, I could not get solvent into the combustion chamber fast enough to keep up with the seepage thru the valves. This was on a motor with only 50 hours on it. THis was not my motor , but another I was fixing. The valve clearance on this motor was good, so it wasn't that the valves moved, they just pitted to the point that they didn't seal.
The chain I have on my bench now looks like the one Kasjok has x3. and that is with about 35 hours on it. my chain out of my 03 WR looks similar with unknown hours.
The piston is measured at the skirt, where specified. I have not tried to measure actual clearance , because it is very difficult to do accurately compared to inside and outside mics.
My theory is starting to sway towards the same conclusion you have gray. I think it is sustained high RPM high load situations that you just don't see in MX at my level. I see no wear on the piston(within reason).I believe the piston skirt may be collapsing slightly or distorting under load. I don't see how that could happen with out visible wear, but who knows?
Again, just looking for constructive conversation on this issue. as far as oil goes, I do run a different oil in the winter compared to the summer.(I use a semi synthetic spectro 5w30 in winter, and a full synthetic silkolene oil 10w40 in the summer, but with no real visible scuffing or erosion , I don't think that is it. When I get this next motor apart(at 38 hours) I will post up pics and measurements, as well as vacuum test AND solvent test results.:p

Dave





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