Does retarded WR timing really do anything good?

I love getting you guys riled up! One thing I did forget to mention is that going to YZ timing will have little or no positive effect on power while using the stock exhaust with the insert. This is due to the exhaust restriction not allowing the formation of a negative pressure area to allow for scavenging.

That said there is a very simple reason we compare our 520's to your little 450's, aside from the ISDE the two machines will almost always be raced against one another! Why shoot yourself in the foot twice once by buying a450 and one more time with a blue one! :D As far as that goes isn't the most common defense of that dog WR that it is so smooth and user friendly? If so then the KTM 450 much be a lot better in most of your books!

I'm sorry (not really) to disappoint you all but the new WR450's are dogs as far as drag race type power is concerned. I witnessed first hand one being out ran by a 02 YZ250f on multiple occasions! That is sad! I wish we would have run it against the 03 250f that was present to see how bad it would smoke it. Darrins 99 had no problem at all running with this 450 and edged it out a few times. 520 was in a different zip code by the time they got into 3rd gear! Not even a fair race looked like a geo metro facing off with a LS1 vette! I do agree with the WR's power being user friendly at least as long as the user doesn't want a trophy! :) Sorry that is just the facts of life!

You guys might want to ask Darrin what his latest favorite bike is! Those smurf humpers are always trying to school me but there aint a whole lot of them around here that have got there teaching degree! I welcome all comers! Step-up at the next WORCS east coast race I'll be entered in 30+A saturday and 4strokeA on sunday assuming I don't qualify for Pro-AM on sunday! I'll sure be trying!Morrison ILL. June 6-7 BEEE THERERERE!!! :)


With 3 posts, dont be suprised if someone steps in and declares you on the edge of trolldom. (Defination of a Troll - One that comes in a particular thread just to bash and harass)

BUT! - There is a lot of merit to what Karl has said, no one should put you in that category yet. So before everyone jumps up and starts pounding their keybord like a madman, keep in mind that I did stay even (with the 450) and like Karl said, even nudge out the WR450 on a couple of occassions. This is on a 5 year old 400!

We both weigh the same, got the same start and went through the gears at the same pace and never got more than a nats pecker away from each other.

Hey mabye it was the Wheel Collar Mod that done it for me!!! :):D (minus the wheel collar of course :D)

The 450 is definatly a great ride but with 6 years under their belt on this bike, I would think Yamaha would have fared better.

Darin is a fireman too! (Gotta get those friends in line before they get you in trouble!)

I gotta say, this is putting a big smile on my face! I THOUGHT that my old 400 was as fast, if not a little quicker, than the two stocker 426's that I have ridden. Nothing that I could prove, but my bike 'felt' faster.

On another note, drag races, while fun, mean little.

(Except when I win, then they mean a lot! My buddies on XR250's FEAR ME! I bought them BajaDesigns headlight grills for Christmas so I would not feel bad about throwing rocks at them!)



The only fire I ever fought was when I had hemmoroids once. :D :D :D :D

Valve overlap and associated changes thereof does not drastically affect the RPM wherein a motor makes its power it does however have an effect on the amount of peak power and the breadth of the torque curve. In the case of the Yamahas, wr timing does in fact reduce the amount of power available at ALL rpm ranges and throttle openings. Show me a dyno report that shows differently and I'll eat my words!

Why is the burden of proof on us? Why don't YOU show us a dyno chart that proves your theory (because that is what it is, a theory, you don't know this to be the case).

I find it curious that you argue from the point of authority when you do not own either of these bikes. Has it ever occurred to you that the YZ has too much overlap? According to your theory more overlap is always better. That is silly.

Anyway, overlap is not all you have changed, the timing has changed also, and your theory fails to address this. But thanks for the insight all the same.

DUH! Who uses the stock pipe with insert!! And as far as drag racing goes, I beat my friend on his XR650R, what does that prove? It proves I am better at drag racing, me the rider, not the machine! I have also been smoked by a 13-year-old kid on a 125 at the MX track, again rider not machine.

Oh yeah 3 posts and I think they have all been in this form, WR envy, looks like a bad case! :)

I now have to own a Yamaha to know anything about them? Wow thats news to me! Please reread my post I stated Intake valve centerline has the greatest effect on rpm range given overlap stays constant (lift and duration also). Changing the exhaust valve timing does not affect this measurement. Sorry if I peaved any one outside of the realm of good hearted fun. I only wanted to help answer this question that I have heard asked a thousand times I dont have dyno data to back up my "theory" but I also dont look at my statement as a "Theory" I back it up with years of wasting my time finding these things out the hard way! I doubt to many people out there who are interested in power are making dyno passes with wr timing, maybe so but I would believe most people who have a dyno already know the answer! I also stated that decreased overlap has its advantages but mostly in forced induction situations. The statement that there is no such thing as free horsepower would allow us all to put 120 main jets in and get a power insrease at some point in the engine range this we all know is BS! Switching to YZ timing is as close to free horse power that you can get. Of course horsepower is not always what is desired even I know this but the differences between wr and yz timing are not enough to make it impossible to ride in slick conditions if anything the aditional throttle response afforded by YZ timing could help in technical conditions, remember it only goes faster if you turn the throttle! I have also heard time and time again (pun intended) that YZ timing makes the bike less prone to stalling. Of course some of you probably like starting your bikes in the middle of a nasty off-camber ledge rock hill climb! to each there own. :)

Sorry if I peaved any one outside of the realm of good hearted fun. I only wanted to help answer this question that I have heard asked a thousand times I dont have dyno data to back up my "theory" but I also dont look at my statement as a "Theory" I back it up with years of wasting my time finding these things out the hard way!

I appreciated your answer, it was insightful, if a little incomplete, and it made me think of some things I hadn't considered before.

But your statement is a theory, your years of experience are lost on us. This is the internet, and unless you have had the YZ and WR cams on a cam doctor or something you can only theorize about the amount of overlap that gives best output. And that is a fact. :)

Even if you did have a cam doctor you would have to make a lot of assumptions about the motor and valvetrain before you decided what cam profile was best. That is as much a black art as anything.

I'm not going to be seduced into believing that something as sloppy as changing the timing by an entire cam tooth is the path to nirvana and includes nothing in the way of a tradeoff. The best setup is probably somewhere between the YZ and WR spec. I had adjustable wheels on my YZ and w/ some help from a few guys here IMO I was able to improve upon them both.

Dam Hick, you square off with the fastest KTM Internet racer in months now and chew him up. Wish I could do that.

Pretty funny TCTrailrider. Still chuckling....

Have you visited the BlackStar Farms Winery yet?

Blackstar Farms

It is listed in Suttons Bay, but you and I would know it out of Traverse City.


As for Blackstar I have not been there. The wine business if fairly new around here but they are all over the place. Alot of well to do retiries from the big cities move to the area and start a winery. Couple of years ago the money was good in grapes but they may have overplanted. Pretty soon you will be able to pick up a winery cheap. Maybe put in a daily fee Motocross track.

peave, peave, peave... madman, madman, madman. :D:):D

To Hick take the number of teeth on your beloved Yamaha cam gear divide it into 360 divide that number by 2, you will end up with a sum that represents the # of crankshaft degrees changed when Yamaha nuetered there WR by retarding the exhaust camshaft. That sum you will find is greater than what one would find with any optimized camshaft profile! I am saying that in no uncertain terms that if you take an optimized cam profile (which as countless cam grinders have found is the YZ cam: not easy to improve on) retard the exhaust timing by the sum you calculated earlier and dyno the engine it WILL make less power across the board! I'm not going to argue with you further! Its just that simple. Of course you probably already know all of this if you as you say improved on the stock cam timing with adjustable sprockets you should have all the dyno data in the world so please enlighten us all and list your results. That is if you did dyno the engine and didn't use the "long Wheelie" method! My only concern in this whole thing is to help my friends go faster. :) Hope I dont get labled a Troll but if so bring on the goats! You know Darrin never did say what his new favorite bike is! How about it D-man, fess up now. :D

as you say improved on the stock cam timing with adjustable sprockets you should have all the dyno data in the world so please enlighten us all and list your results.

What makes you think I have access to a dyno?

Further, what makes you think I care what any dyno says? The dyno isn't riding the bike, and dyno numbers matter very little for dirt bikes IMO. If RC's tuner knows a certain setup makes more power, but RC turns slower laps with this setup, is he going to argue with RC? Not if he wants to keep his job.

You were the one that brought dynos into this. I've tried different cam timing (exhaust and intake) on the 426, you have not. That doesn't mean I'm right and you are wrong, it just means I have more credibility. :)

Before you flame me I'll acknowledge that my credibility on the internet isn't going to help me at the races.

My only concern in this whole thing is to help my friends go faster.

Then forget about what any dyno says. My "long wheelie method" is a more robust means of determining what will make Moo go faster than any dyno.

Hick take the number of teeth on your beloved Yamaha cam gear...

BTW one tooth is 22.5°

Thanks for the math lesson, but I think you are off on that also.

And it isn't "my beloved Yamaha." Don't go there, I ride a Honda. :)

Now you guys!!! Am I gonna have to break it up? :D

Actually Im kinda enjoying it. :)

As long as it dosent get out of hand it joys me to see 2 gearheads go at it head to head. I wish I could chime in, but you guys are WAAAAAAAAAAAAY over my head.

If you wanna talk seal savers, or favorite tires or what goggle lens to wear for fogging, them Im your man! :D But all that tech talk about cams, and teeth, and backpressure and whatnot, I'll leave to you 2. Just keep it up, its very entertaining.

Now, on to the subject I have been avoiding.

Lord knows I still love my 400 to death. It has always been and still is a great ride. But this past weekend, I cheated on her and rode another. And I have to tell you, it felt gooood. The 520 worked for me very well, I just cant say enough about it.

OK, SO I LIKE THE 520!!!!

That dosent mean Im leaving the 400, ok?

OK, Karl.

You've worn out your welcome. Now, run along like a good little boy and annoy your teammates over on the orange message board.

Maybe they ride dynos and drag race and drink enough beer that you can convince them. It doesn't seem to be working very well here.

Your friend (as long as you leave),


Like it or not I am a team mate to anyone who rides (preferably races) dirt bikes. I do ride a KTM but I also ride every other thing I can get my hands on. I have ridden all of the late model 4 strokes with the exception being the elusive KTM 450SX. I like them all. Truth be know and assuming the new SX KTM wouldn't change my mind, if I was to own a motorcycle to race only in 03 it would be a YZ 450f I have ridden them and absolutly love the motor! I however will remain true to the orange as I have been with them a while and have amassed a lot of knowledge and more importantly spare parts!

As far as the whole dyno debate goes, I am fully aware that we don't race dynos, but if you want to measure the performance of an engine that is the only way to get accurate data. Way to many variables in the seat of my britches. Add to that someones preconcieved notions of what has changed and you have a recipe for inaccurate "feelings"

I might also add that drag racing is a good way to see the differences in an engines WOT output! That said I don't think I have had to drag race any one after the first turn in years, but that doesn't make the first turn unimportant!

DUH! Who uses the stock pipe with insert!!

Yamaha make two types of tail pipes for the WR ,the version we get in Europe has a welded end pipe < 1 inch , not a bolt in insert !

DUH - don't jump to conclusions with out the facts :)

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