YZ450 or KX450


59 replies to this topic
  • DesertRacer2

Posted March 07, 2008 - 10:21 AM

#21

you compare your kx250 and kx500 to some guy's kx450f? the blown head gasket could be an mftr error, and i used to have a 98 kx250 and after 8 years on the same piston (who knows how many hours) the thing was still in amazing condition. the crankcase seal went out and all the oil went with it and destroyed the engine, but all of the mechanics that looked at it said it was a freak accident worthy of happening to any bike. but still she ran rock solid up until then.


I am sure the blown head gasket was a manufacturer error. However, doesn't that seem ridiculous for a new bike to have a problem off the show room floor? When I spend $7000 on a new bike, it better be perfect and all my new Honda's and Yamaha's have been. Weird!

  • dirtbiker771

Posted March 08, 2008 - 04:53 PM

#22

You have to take into consideration the owner of the bike also. I just sold my 06 KX450 and never had a problem, hell the valves hadn't even moved when I sold it. I also keep the oil changed and air filter cleaned and don't bounce it off the rev limiter every chance I can. I am looking at the YZ for this year, haven't decided what I will replace my KXF with yet. But wouldn't hesitate for one minute to go back to a Kawi. I'm mainly looking at the YZ for a change of pace. I loved that Kawi though and that's the only thing making me have second thoughts.

Don't believe everything you read in those mags.

  • mxboy2661

Posted March 08, 2008 - 05:50 PM

#23

I would reccomend the yamaha.. I have 2 08 450's I have had every brand and nothing beats a yamaha! I reccomend Tokyo mods carb mod with a DR D pipe INSANE!!!!!!!!!!!!!!!!!!1

  • harwood39

Posted March 09, 2008 - 12:38 PM

#24

im for sure gonna go with yamaha, they have a killer deal on financing!!! up til may 31st.... 750 cash back and 69 bucks a month!!!

  • todds924

Posted March 09, 2008 - 06:01 PM

#25

Yeah... that makes me feel better (no sarcasm). Why are guys rebuilding the motors at fifty hours... not trying to contradict you or anything. Just wondering.


Maybe they think they need to or simply have the money to do it. Have you ever looked in your service manual and seen the maintenance intervals for top ends???????? I think that is ridiculous. I beat on my 06 for over a year and over a hundred hours and didnt touch a thing... just frequent oil changes and a fresh air filter every ride. I think i replaced the spark plug once and checked the valves twice.......they were still in spec. I'm not sure but check it out for yourself what the service manual recommends for time on replacing a piston...It is ridiculously low.

  • etug321

Posted March 10, 2008 - 01:02 PM

#26

Alrigth guys. I just got a much better job and can finally afford a brand new bike. Im stuck tho. I have only been on yamaha so do i stick with them? or do i go for the new KX450? Both bikes seem great. I like things that both of them have. The only thing i dont like is the new YZ seems to sit 2 in higher than previous years... IDK if this is just how the dealer set up the 08 they have but they still have a new 06 right next to it and it is 2 in lower than the 08. I am 5'9 so the 2 inches scares me as i cant touch easily.


is the yz to tall? im 5'5'', i just shaved an inch of the seat foam and it was good to go.:thumbsup:

  • Scspringer912

Posted March 11, 2008 - 05:50 AM

#27

okay i rode an 08 yz and 08 kaw.. the kaw motor was hands down a beast. to much for me even coming off an 07 crf 450. but i am always reading on here about how kaw's need this or need that for pistons and all this every 20 's. what's the deal on this. are people just putting new top ends for the hell of it or are they really blowing up? because no matter how fast the kaw is i damn sure don't want to buy rebuilding ever so often. I know yz are the longest lasting that's for sure. if they only put a motor in that thing

  • wolfie12

Posted March 11, 2008 - 07:08 AM

#28

I did a full season of racing last year. None of the vets I know made a full season with their KXfs or RMZs without catastrophic motor failure. I'm told that is largely due to the lack of oil flow to the valve train. Take a head off a Yam/Honda and remove the plug-turn over motor-oil squirts up onto the valve train. Do that with a RMZ or KXF...nothing, unless the motor is running, ie., less flow. I also read something about KXFs having a change this year that directs oil flow to the heads. For the kind of money we spend, this crap is unacceptable.

  • NorCal

Posted March 11, 2008 - 11:45 AM

#29

I did a full season of racing last year. None of the vets I know made a full season with their KXfs or RMZs without catastrophic motor failure. I'm told that is largely due to the lack of oil flow to the valve train. Take a head off a Yam/Honda and remove the plug-turn over motor-oil squirts up onto the valve train. Do that with a RMZ or KXF...nothing, unless the motor is running, ie., less flow. I also read something about KXFs having a change this year that directs oil flow to the heads. For the kind of money we spend, this crap is unacceptable.


:thumbsup: :eek: :D :ride: :lol: :ride: :ride: :ride: :cry: :eek:

There are so many god damn conflicting reports on reliability of these Kawasakis!

What year were the KXFs? I know the 2007 motors are quite different than the 2006s.

  • Scspringer912

Posted March 12, 2008 - 09:20 AM

#30

so can we all agree that the darn yz is the most dependable longest lasting ha bike out there.. we all know everybody does. i just wish they would make it a little more powerful

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • grayracer513

Posted March 12, 2008 - 09:55 AM

#31

Making a YZ450 more powerful is an extremely simple and relatively low cost matter. Making a bike handle, getting the suspension to work, and most of all, building reliability into a bike are vastly more difficult when you have to do it yourself.

  • NorCal

Posted March 12, 2008 - 10:03 AM

#32

so can we all agree that the darn yz is the most dependable longest lasting ha bike out there.. we all know everybody does. i just wish they would make it a little more powerful


YZs are plenty powerful. Look at the dyno charts, and you'll see they make the
same peak power. It is just deceiving when you ride it because it comes on so smooth.

  • grayracer513

Posted March 12, 2008 - 10:14 AM

#33

That's true of the '06 and '07, but as delivered, the '08 does have a pronounced dip in the curve between 4000 and 6000, which is what counts as low-mid these days. Most any pipe more or less eliminates that, though, and the stock '08 does have something around 52 hp at peak.

  • Pappy141

Posted March 12, 2008 - 10:48 AM

#34

I'm picking up my 08 next week. I'm coming off a 07 Honda 450. Here's my concern...The Honda is more than efficient when it comes to pulling good starts, will the 08 Yam be able to hang on long start straights? I plan on replacing the stock silencer with a FMF, is this enough?

  • Home Track 250

Posted March 15, 2008 - 06:17 AM

#35

Hello

I am considering purchasing a 04 Yzf 450 for 2800 the thing still has original tires in awesome shape. I keep reading how the o4s and 03s are two much to handle and real heavy in turns what is your opinion. I will be coming off of a 2004 RM 250. Actually I was trying to ask this question to the person who owned the 03 on one it, think on page two, just in case this post doesn't seem to fit this section. Just new at this so not sure how to attach original question yet. Definately open to all opinions though.

Thanks, Tim S.

  • harwood39

Posted March 16, 2008 - 10:57 AM

#36

i have a yz426, and i came off a yz250, i didnt notice the weight difference. When you lug it through corners it feels heavier, but when your ripping on it, it feels fine. The 4strokes love to rip through corners. if you dont they tend to wash out or fall over...

  • Home Track 250

Posted March 18, 2008 - 04:49 PM

#37

i have a yz426, and i came off a yz250, i didnt notice the weight difference. When you lug it through corners it feels heavier, but when your ripping on it, it feels fine. The 4strokes love to rip through corners. if you dont they tend to wash out or fall over...


Thanks for the reply. I have decided to go with the 04 not the same as the 2800 one though going with a different one the original one was not as nice. Already checked Yamaha dealer in town for the Gytr 8 ounce fly wheel and puller said just bring it in and they'll pull it for me for $10.00 , really like the parts quy there he always gives me a discount and treats me good when I go in. I think I will also slide the forks up 5-7mms sound like that is the average from what I can tell. Really looking forward to this bike love my sons 04 250f feels so stable and likes to hold that straight line compared to my RM ,although I have liked all my RMs, had 4 so far.

  • todds924

Posted March 18, 2008 - 05:53 PM

#38

I did a full season of racing last year. None of the vets I know made a full season with their KXfs or RMZs without catastrophic motor failure. I'm told that is largely due to the lack of oil flow to the valve train. Take a head off a Yam/Honda and remove the plug-turn over motor-oil squirts up onto the valve train. Do that with a RMZ or KXF...nothing, unless the motor is running, ie., less flow. I also read something about KXFs having a change this year that directs oil flow to the heads. For the kind of money we spend, this crap is unacceptable.


I did a full season of racing and nobody i knew with a crf made it even half the year. I race an 08 yz, my buddy races an 08 KX....over 100 hours...both are bulletproof. All i see at the shop i work for is CRF problems.... a token kxf or yes....even a YZ...matter of fact we just had an 08 yz with a cam chain failure. On the whole..........From what i see working on these things everyday....the yz's and KXF 450's are solid.

  • wolfie12

Posted March 18, 2008 - 06:14 PM

#39

Don't get me wrong, not trying to start a brand war either, just presenting some anecdotal experience of my own. My CRF was making some funny noises by the end of last season, but I sent it down the road after 110 motos and a whole bunch of practice laps, it never puked on me.

  • todds924

Posted March 19, 2008 - 06:20 PM

#40

Don't get me wrong, not trying to start a brand war either, just presenting some anecdotal experience of my own. My CRF was making some funny noises by the end of last season, but I sent it down the road after 110 motos and a whole bunch of practice laps, it never puked on me.


Sounds like that was a sound decision!!!!!! You definitely got everything out of it then.





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