yzf valves vs crf valves?


41 replies to this topic
  • nfrcr31

Posted August 23, 2005 - 12:00 AM

#21

Thanks guys....I think my red blood is turning BLUE....

  • Slowmotion426

Posted August 23, 2005 - 01:17 AM

#22

I do have to make this disclosure: I've been racing my '04 WR for two seasons, and hopefully this winter I'll get around to checking my valves for the first time. :D

Jerry



I have an '01 YZ426F that I bought new back then. I've only shimmed one intake valve in all that time. :D

  • Satch0922

Posted August 23, 2005 - 04:18 AM

#23

. A couple guys with YZ426's did have some issues.



Kirtwell had 400+ hours on his 01 YZ426 and no valve problems. My 426 had a good 200 hrs....zero issues. That is why it is difficult to think a bike that has to have them replaced at 50 hrs is acceptable.

  • CRFThumper

Posted August 23, 2005 - 04:28 AM

#24

It's a simple matter of superior quality, that's all.

The answer is no, I am not going through it. My '03 is still stubbornly refusing to need it's first valve adjustment. I did have to replace the valves in my 250F in January at about 400 hours, but it has not needed a reshim since before I bolted the head on.

I have more trouble with my sundial.



Same here my 03 has been spot on since new!I do ck them often though,heres something for the Honda guy'sI'm almost wanting them to be a little out so i can do them!!(it would just make me feel better) :D

  • Jetsprint2

Posted August 23, 2005 - 07:17 AM

#25

Not sure how many hours are on my 04' 450 but I ride the hell out of it (I need an hour meter). Checked the valve clearances this morning and they were exactly spot on.

  • MotoGoalie

Posted August 23, 2005 - 10:06 AM

#26

I bought my 03 used in March. It was in spec, it starts nearly first kick everytime now and I just finished an enduro that had a lot of clutch slipping and WFO. It runs like a top.

I wouldn't take a CRF if you gave it to me. I'd just trade it in for a YZF.

BTW, at the RMEC race I entered, the bikes of choice are a very noticeable majority consisting of a 50/50 mix of Blue and Orange with a scattering of green and a touch of red. That's what the start line looks like in Colorado enduro racing.

  • SureBlue

Posted August 23, 2005 - 11:19 AM

#27

I wouldn't take a CRF if you gave it to me. I'd just trade it in for a YZF.

I agree with you about Yamaha reliability, but I would also love to have a CRF450 if someone paid for and did the maintenance and kept me constantly on it without garage days. I have to say the bike is awesome despite possible problems it may have if you're unlucky. I think I have enough to keep already 3-4 blue bikes going strong.

  • eazrider

Posted August 23, 2005 - 11:23 AM

#28

I have an '04 YZ 450 that I bought in November of '03. I have motocrossed it, but generally it has spent it's life blasting across the desert, or up a high speed sand wash. I have yet to require a valve adjusment.......

  • Mike_socal

Posted August 23, 2005 - 11:33 AM

#29

This isn't a scientific poll by any means, but I've talked to quite a few people that I race with. I haven't run into any Yamaha owners (YZ450's and WR450's) with valve problems. A couple guys with YZ426's did have some issues. The Honda owners seem to fall into one of two categories: guys that check their valves regularly and have no problems, and those that don't and have to buy a new head and valves.

And in all fairness to 2-smokes, I haven't heard of a single one with valve problems :D

Jerry


I agree. My Honda hasn't had a single valve problem yet. I did however replace "the valve" for the hell of it.

  • 642MX

Posted August 23, 2005 - 06:09 PM

#30

I posted earlier about my crf450 valve problems....Does any of you YAMAHA owners have valve problems???? If this is a reoccurring problem I'm going back to 2-smoke!!!!!




I've got 250+ hours on my 02 426, and my valves still haven't tightened up.

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  • Satch0922

Posted August 23, 2005 - 06:13 PM

#31

I see a trend here.. :D

  • ONLY4STROKES

Posted August 23, 2005 - 07:44 PM

#32

Isn't it true though that the CRF valves wear out faster because the four-valve design takes more of a beating against the valve seats than the five-valve design of Yamaha?

  • jerryls

Posted August 23, 2005 - 08:10 PM

#33

Isn't it true though that the CRF valves wear out faster because the four-valve design takes more of a beating against the valve seats than the five-valve design of Yamaha?



Go over to the CRF forums. Seems to be a new theory every week.

Jerry

  • 99wr400

Posted August 23, 2005 - 08:15 PM

#34

The stainless yamaha valves will go forever.

  • yz_for_me

Posted August 23, 2005 - 08:31 PM

#35

I agree Jerry, Honda owners do usually fall into those two categories. I maintain my Honda as I would a Yamaha. Even if the Yamaha has more reliable values that doesn't mean you can ignore maintenance longer on one. Any color of bikes are great these days, but if you don't maintain them then you're bound to have issues. If take care of your bikes and perform regular maintenance valve issues should be non-existent or not very serious. Even though I own a Honda I'm not being bias, it just comes down to one thing..... MAINTENACE…


True enough, but not all "maintenance" is created equal. To me there is a difference between normal week to week maintenance and yearly maintenance. Checking your valves should be one of those yearly kind of things. Shimming them should be rare and replacing them should be almost unheard of. Don't give me the "this is a high performance engine" story. That's just an excuse. The other manufacturers have figured out how to build "high performance" engines w/o valve issues. Honda could take care of this problem if they wanted to, but that would require admitting there is a problem.

This topic really burns a lot of Honda guys, but denying the problem doesn't mean there isn't one. I think Honda's legendary reputation for reliability, and the fact that every other aspect of the CRF is superb, makes it hard for Honda guys to admit the CRF may have a flaw. Sure, most CRF riders never have valve problems (there's a poll on the CRF forum to prove it), but it's pretty hard to argue the Honda doesn't have significantly more valve problems than any other brand. Just look at the frequency of the topic in the different forums. In the CRF forum it's a regular topic. In the blue, orange and yellow forums it's hardly ever talked about.

On the other hand, if you don't mind the risk or time and $ involved to "maintain" the CRF, you are rewarded with a hell of a good bike, probably even the best performing bike of all time....at least until the '06 YZ450 comes along :D

  • YZLEE

Posted August 24, 2005 - 07:26 AM

#36

And in all fairness to 2-smokes, I haven't heard of a single one with valve problems :D

Jerry

The power valve on my '91 KTM 300 snapped into three pieces. Does that count?

  • jeff_wsu

Posted August 24, 2005 - 07:46 AM

#37

Don't give me the "this is a high performance engine" story. That's just an excuse.


I haven't heard anybody say anything in this topic about the high performance engine and using that as an excuse, so I'm not sure what you're talking about.

This topic really burns a lot of Honda guys, but denying the problem doesn't mean there isn't one.


I've seen a lot of issues with valves in the Honda forum, so I wasn't denying there was a problem, but I also see a lot more red bikes than any other at the track so I would think there would be more posts regarding issues and recognizing a problems. But problems are prevented with maintenance, that's all I was referring to. I check/maintain my valves every 10-15 hours and have had no issues. That's not to say I won't, but it makes me feel warm and fuzzy inside to know I'm taking care of my bike, regardless of brand. And like I said before, any bikes now and days are great, but you can't ignore them because they're "supposedly" more reliable than another brand. I've seen situations time and time again where someone thinks their bike is bullet proof because it's a certain brand and then they're the ones with the largest problems when the begin to occur, which could have been prevented all along if they would have taken preventive measures in the first place.

  • ONLY4STROKES

Posted August 24, 2005 - 11:47 AM

#38

Go over to the CRF forums. Seems to be a new theory every week.

Jerry

Oh, thats just what I heard from Motocross Action mag.

  • Satch0922

Posted August 24, 2005 - 06:05 PM

#39

don't worry about the valves...you know they are a problem so if you buy a red bike replace them and your good.

Now...what about the water pump seal that goes bad at will and causes overheating to the point of cracking your header?

Oh and what about the faulty oil pump that can go at any minute and trash your engine?

These are things I have seen on the red bikes in the last 90 days. I have not seen them on any other bike ever. Real world...not magazines.

  • grayracer513

Posted August 24, 2005 - 08:50 PM

#40

Oh, thats just what I heard from Motocross Action mag.

One of the things you'll find out about the guys at MXA is that they're pretty good, but they aren't really engine people.

The four valve theory is based on the idea that the larger valves are heavier, and since there are fewer of them they have to lift farther, and thus close harder to allow the same flow volume as the YZF's 5 valves. If that were true, the 450's would wear faster than that 250F and CRF250, and they don't.

Poorly, or aggressively ground easing ramps on the closing side of the cam could be at fault, which follows the same general thought pattern, but using an aftermarket cam in a YZF doesn't seem to shorten valve life that much either.

I still think it's a simple question of quality.





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