Top End on my 426, what a waste of time!


32 replies to this topic
  • FFRacing79

Posted January 26, 2005 - 08:08 PM

#21

I have worked elbow to elbow with Eric and he did not write the article to drum up business. One thing some of you fail to realize is that although parts may "look" OK, they can be fatigued. Fatigued parts break and can cause massive $$ repair bills.
Put a dial bore guage in a cylinder with 1 years riding on it...that cylinder has been compressed with 40 ft/lbs of pressure and been heat cycled numerous times. Still think it is OK?
Just think of that piston, which has almost no skirt for support, and all it has been thru the last season.
Oh it looks ok...what a waste of time tearing it down.
I built my business on guys that thought "I will just wait till it breaks" mentality...as did Eric.
Some of you should stick to riding and leave the mechanics to those that have a clue!
The saying goes,"pay me small now, or pay me BIG later".

  • 642MX

Posted January 26, 2005 - 08:38 PM

#22

I have worked elbow to elbow with Eric and he did not write the article to drum up business. One thing some of you fail to realize is that although parts may "look" OK, they can be fatigued. Fatigued parts break and can cause massive $$ repair bills.
Put a dial bore guage in a cylinder with 1 years riding on it...that cylinder has been compressed with 40 ft/lbs of pressure and been heat cycled numerous times. Still think it is OK?
Just think of that piston, which has almost no skirt for support, and all it has been thru the last season.
Oh it looks ok...what a waste of time tearing it down.
I built my business on guys that thought "I will just wait till it breaks" mentality...as did Eric.
Some of you should stick to riding and leave the mechanics to those that have a clue!
The saying goes,"pay me small now, or pay me BIG later".


The saying goes "pay a little now or a lot later". Nice attitude by the way, and I'll make sure to keep that in mind if I ever need any "REAL" mechanic to work on my bike. Oh congrats on working with the legend himself. :cry:

  • FFRacing79

Posted January 26, 2005 - 09:25 PM

#23

Unless I misread your reply, you missed the entire meaning of my post.
I have many times rebuilt motors that were left "too long". I read in alot of these posts that "everything looks fine". Can the majority of readers here measure fatigue? Or even if a cylinder is out of round or taper? Do you know anything about piston taper and what it means to the life of a piston?
I was only trying to convey a message. There is more than meets the eye. Better safe than sorry. Any other cliches you care for?
As far as working with the "legend", Eric is an old and valued friend. He is known world wide for his talents, and for some of you mere mortals to question his ethics is absurd.
Damn I hate it when some one I don't even know pisses me off with some stupid comment I should have ignored.

  • biznet1

Posted January 27, 2005 - 12:03 AM

#24

Oh no, biznet, you have bought the most reliable real racing thumper, don't worry about that. I would anyway have the condition checked/evaluated if you don't know how many hours it has been ridden and how it has been serviced.
Just with hours the risk of a big bang increases and therefore better to do something in good time. As somebody here said, these are more reliable than some of the cars out on the streets. :cry:


Thanks,
I will order a kit and let my experienced motor head friend help me. I am decent with a wrench, but I sometimes take things for granted. It's a 2000 model so it probably needs it.

  • RippinInColorado

Posted January 27, 2005 - 09:15 PM

#25

Does a leakdown test tell for sure whether to rebuild? Clearly, that tells you about the rings and the valves and the head, but is it safe to figure if the leakdown results are okay, the cam chain is okay too? What other parts to worry about?

As stated before in this thread, I have a pretty hard season in '03 (30 races plus 20 or more practice sessoins) and a almost-nothing season in '04 (4 races, a half dozen practice sessions) on my '03 YZ450. I have not popped the top to check anything. Ever. Starts easy, runs great, no backfiring or indication of trouble at all.

I have no 4 stroke mechanical experience or I would have torn into it already just to be sure. I don't plan to run it very hard in 2005.

Will it keep going? Or is it due for piston/rings/cam chain/?? ??

I know there are no certain answers, no guarantees. I'm just looking for opinions. Is it likely to be fine for another dozen rides in 05? Or am I tempting fate?

  • yamaboy23

Posted January 28, 2005 - 08:00 AM

#26

Everyone is entitled to their own opinion and everyone here can only assume on how each individual motorcycle has been treated
Thus posting here about any condition is just an evaluated guess based on the information given
On the general rule 4-stroke motors require less rebuilding than 2-stroke motors-still its all based on how they are treated and maintained
And thats a call that each of us are trying to make
These new age 4-stroke MX bikes are truely amazing in quality and performance
Ive often thought of replacing my current bike (which is an exceptionally clean 2000 model) and i find myself saying "NO"
So if you take care of your stuff and do periodic maintenance then your bike will last longer than the average,if not then you will be at the local dealership buying parts prematurely that wore out.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • vetplus40

Posted January 28, 2005 - 02:43 PM

#27

It can also be found on www.dirtrider.net

  • vetplus40

Posted January 28, 2005 - 02:47 PM

#28

Engine rebuilds and upgrades are the life Blood of Eric Gorr's business (and he does Great work!). I totally expect that kind of article out of someone who needs the business to survive. The funny thing here is that many folks are falling for it after many of us have reported for years that it was completely unnecessary. This is just another expensive lesson for those who figure "If it's in Dirt Rider, then it must be true."

Bonzai :cry:


Eric is entitled to his opinion based on what he sees coming into his shop. Implying that he used "scare tactics" to drum up business implies that he is dishonest and untrustworthy. I have read a few of his articles and I do not get that impression.

  • 642MX

Posted January 28, 2005 - 07:28 PM

#29

Okay I started this thread because I tore down my 426 and in my opinion everything appeared in good shape. I just finished replacing the piston and cam chain and installed a 450 cam. It runs like a dream again. Do I still think it was a waste of time........I sure do! (maybe not the 450 cam, its really nice) but it probably did not need the piston and rings replaced. This is my opinion...Yours may differ, and thats ok, because we can all think for ourselves...right? Anyways I still have my opinions on Gorrs arcticle and some information someone else posted on here. I think YZF's are great bikes that hold up very well if they are cared for properly. If you all want to rebuild your 400/426/450's go ahead (its almost as easy as a two stroke) but I will wait until my 426's burning oil before I touch the top-end again. :cry:

  • jmics19067

Posted January 28, 2005 - 08:55 PM

#30

do you have steel valves or titanium valves in your 426? I forget what year Yamaha started putting the Ti valves in

The problems I have seen at work with the yfz450 quads tends to make me think ERic Gorr's article isn't too far off the mark for making sure that you won't have any problems. He makes his money repairing engines , probably sees a lot of negligable maintenance, more so than most of us. He also makes his money buidling higher performance engines so he has people that run those engines against the rev limiter more often with more of a load on it whether it is sand drags,flat track , supermotard racing etc etc ,then most of us mere mortals.

Always measure your piston skirt and cylinder taper/out of round when you have your top end apart. I really enjoyed the thought of keeping a log of your valve adjustments to give a slight idea of valve face wear. It does not take much for an improperly seated air filter, valve float from a weak spring at 11,000 rpm ,or pinging from a 12&1/2 to 1 compresion piston racing engine being run on regular gas to cause a 2500$ bill. Which is something he probably sees everyday.

I had no problems with my old wr 400, I hope to have no probelms with the titanium valves in my new wr 450 BUT I tear down my bike every winter and give a wheels up rebuild (along with oil and filter change every ride and basic maintenece repairs throughout the summer). As soon as I start to see any valve wear whether visual inspection or by checking valve tappet clearance I am going to start thinking of stainless valves.

  • biznet1

Posted January 29, 2005 - 01:46 AM

#31

do you have steel valves or titanium valves in your 426? I forget what year Yamaha started putting the Ti valves in

The problems I have seen at work with the yfz450 quads tends to make me think ERic Gorr's article isn't too far off the mark for making sure that you won't have any problems. He makes his money repairing engines , probably sees a lot of negligable maintenance, more so than most of us. He also makes his money buidling higher performance engines so he has people that run those engines against the rev limiter more often with more of a load on it whether it is sand drags,flat track , supermotard racing etc etc ,then most of us mere mortals.

Always measure your piston skirt and cylinder taper/out of round when you have your top end apart. I really enjoyed the thought of keeping a log of your valve adjustments to give a slight idea of valve face wear. It does not take much for an improperly seated air filter, valve float from a weak spring at 11,000 rpm ,or pinging from a 12&1/2 to 1 compresion piston racing engine being run on regular gas to cause a 2500$ bill. Which is something he probably sees everyday.

I had no problems with my old wr 400, I hope to have no probelms with the titanium valves in my new wr 450 BUT I tear down my bike every winter and give a wheels up rebuild (along with oil and filter change every ride and basic maintenece repairs throughout the summer). As soon as I start to see any valve wear whether visual inspection or by checking valve tappet clearance I am going to start thinking of stainless valves.


Good words. This sounds like good middle of the road common sense.

  • 642MX

Posted January 29, 2005 - 04:12 PM

#32

do you have steel valves or titanium valves in your 426? I forget what year Yamaha started putting the Ti valves in


titanium valves

  • jmics19067

Posted January 29, 2005 - 05:10 PM

#33

when they fail (not if) I hope you only burn the valve/seat causing an irritating pop to the point of not being able to start the bike and not the head breaking off.

Remember that the Yamaha manual and tuners/ mechanics like ERic are telling you " You have a racing machine ,it requires a lot of maintenance if you follow these guidelines you should not have any problems having a machine that is very competitive in its class. If you don't follow these guidelines you are on your own." They are telling you that your machine will easily last a season of pro racing if these , any and all preventive steps are performed properly.

I am not a pro racer, I don't really think these "rules " apply to me but since they don't know me or how I ride they cannot give me accurate advice for a maintenance schedule. So I take it upon myself to do what I think is best and if I am wrong and a shattered piston or dropped valve too late I bite the bullet with noone to blame but myself.





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