yz450f flywheel weight

I want to smooth the power out in a 2003 yz450f someone recommended a zip-ty 8oz. flywheel weight. Is this a good idea for someone who mostly rides and races motocross?

i went with a 6 oz on an 04 450 and it worked out great....(motocross use only, doug dubach also suggested a 4-5 oz)

Yes and maybe not. There are two different kinds of flywheel weights available for your bike. There are the bolt-ons, like the Zip-Ty, and Stealy, and the welded-on weights like the Yamaha GYT-R and the Dr.D.

Bolt-ons are cheap, but they block the view of the timing marks, have at least some chance of working loose, and are not as effective as welded ring weights per ounce added because part of their weight is near the center where they bolt on.

Welded weights cost a little more, but are more effective per ounce because their entire mass is at the outside diameter of the flywheel. Furthermore, they are balanced after welding and will never work loose from the flywheel. I would guess the Zip-Ty 8oz would be about like a 5oz welded ring.

I recommend the Dr.D. He offers flywheels in 4, 6, and 8 ounces added, and the 6 is the one he sells the most of. He does them on an exchange basis; details are at his web site: Dubach Racing/flywheels He will also let you swap one of his back for one of a different weight at no charge other than shipping, even if you were not the person who bought it in the first place.

The GYT-R's are available in two sizes, one known as the "racing" model, and the other as the "offroad". They work out to about 5 and 7 ounces added. The racing model is hard to find now, but it was also used as standard equipment on the '04 and '05 YZ450, so if that's the one you decide on, you can find it that way.

I had a Dr.D 4oz on mine, and it was still a little light. The GYT-R I have now is just a little heavy, but not bad. I'm going to swap my 4oz for a 6 and try that next.

well i was a little confused after reading several posts like grayracers, that the 04-05 ran 5 oz more than the 03. the reason being ,when i went to order a fw from race tech they listed them all together(+6,+8,+13) for 03-05. so it stood to reason that if they were different there should have been different part #'s for 03 +6 and a 04-05 +6 ???? so i called race tech and they said the info they had was that they were the same 03-05. so having to actually see for myself i looked up the part #'s for all of them (03-05) and guess what they all take a 17oz- 5TA-85550-00-00 !! so all of you that were under the impression you had +5 in your 04-05 were misled. :) so all that out the way,i'm guessing i should run the +6 with the rekluse(would be equal to +8 together) as traction is pretty good right now, but it needs a touch of mellow in the transition from bottom to top. but at the same time i don't want to lose any snap. i'm thinkin the + 8 might be too much?

well i was a little confused after reading several posts like grayracers, that the 04-05 ran 5 oz more than the 03.... so having to actually see for myself i looked up the part #'s for all of them (03-05) and guess what they all take a 17oz- 5TA-85550-00-00 !! so all of you that were under the impression you had +5 in your 04-05 were misled.

... i'm thinkin the + 8 might be too much?

Intriguing. The info I got came from Yamaha. They do sometimes supercede part numbers, so I'm not ready to agree that there's no difference in the OE '03 flywheel and the 5TA-85550-00-00, but it merits more research. It may also say something that the lighter "racing" GYT-R flywheel is no longer offered for the '03, only the heavier "off road".

Dubach used to have a description on his web site of his +8 as making the engine feel "lazier, like a Honda", so you may be right in guessing the +6 would be better. The GYT-R +7 I have now is as heavy as I think I will want to run.

both the 'racing' and 'offroad' are still available from gyt-r for 03-05 according to the site. and they lump the same part #'s for all 3 yrs also :) $99.95 is a pretty good deal.

It is a good deal. So's the Dr.D for $10 bucks less. On one hand, you can buy the GYT-R outright and have two to switch between. On the other, when you buy the Dr.D, any concern you have about selecting the wrong weight is alleviated by the fact that he'll exchange for free. Now that I have one of each, I'm sitting pretty fat. :)

I still smell fish on the '03/'04 question. Yamaha just changed their web site. Before they did this, there was a link on their accessories page that said "put in your year and model, and we'll show you only what fits your bike". That link is gone. Originally, both flywheels were displayed for all models. More recently, while it was still there, you could put in an '03, and only the heavier flywheel would be displayed (which is sort of backwards, really). Now, I just don't know, but I'm going to find out if I can.

I have a bolt on 12 oz from steahly and love it.I ride desert and smoothed out the "hit".But for mx I can't say you'll really want it.

just ordered the +6 race tech today,i'm gonna weigh them both(stocker and the new one) to make sure its not just +1 :)

Well, here is another opinion for everyone! I just put a GYT-R flywheel on my '03 YZ450F and as far as I can tell I've got the "racing" one. Part # 5TA97-50-00 and was told by Yamaha that it has a inertia weight of 5.0 ---- stock is 3.6 ----. I don't know what the actual "weight" is but the guy at Yamaha didn't recommend the other flywheel for MX. It seems to work well but can anyone help me with the fuel screw? How many turns out do you guys run them. I'm at 800' in Illinois with low humidity for now ------ about 75 degree temp. Also shed some lite on what fuel you run ---- I've tried AV100 aviation fuel and Sunoco regular race fuel. Seems to work o.k. ---- pump gas in our area is pure crap!

just ordered the +6 race tech today,i'm gonna weigh them both(stocker and the new one) to make sure its not just +1 :D
I wanted to do that with the GYT-R before I hung it on the bike, but the only scales I have here are a very accurate small one in grains, and a couple of big ones in pounds. :) It should have come up 3.5 ounces heavier than the Dr.D I have.

i'm pretty sure the triple beam i've got goes to a kilo,so thats plenty :thumbsup:it'll be over a week before it gets here :)

I want to smooth the power out in a 2003 yz450f someone recommended a zip-ty 8oz. flywheel weight. Is this a good idea for someone who mostly rides and races motocross?

Grey is right - it will depend on your riding skills and ability -

For me - anything over 5oz is ---- TOO much flywheel

4oz or 5oz is all you need -

Well, here is another opinion for everyone! I just put a GYT-R flywheel on my '03 YZ450F and as far as I can tell I've got the "racing" one. Part # 5TA97-50-00 and was told by Yamaha that it has a inertia weight of 5.0 ---- stock is 3.6 ----. I don't know what the actual "weight" is but the guy at Yamaha didn't recommend the other flywheel for MX. It seems to work well but can anyone help me with the fuel screw? How many turns out do you guys run them. I'm at 800' in Illinois with low humidity for now ------ about 75 degree temp. Also shed some lite on what fuel you run ---- I've tried AV100 aviation fuel and Sunoco regular race fuel. Seems to work o.k. ---- pump gas in our area is pure crap!

VPU4 is the stuff - stay away from aviation fuel - it will eat the seals in the carb...

i went with the + 4 oz steahly complete flywheel.just what the bike needed. :)

I bought a standard 04 flywheel and put it on my 03, it just took the edge of the hit and helped with cornering in a higher gear. Worked great 4 me and was the same price as a aftermarket weight .Beat thing is I still have the option of going back to the standard 1.

that would be a perfect example of the placebo effect if this is the same part :) grayracer,you explained the yamaha parts number in a recent thread and said that the original parts ended in 00-00 and revised parts would have a 01 or 10. 03 pn for the rotor-5TA-85550-00-00 , 04 pn 5TA-85550-00-00 , 05 pn 5TA-85550-00-00 :) dan450,do you recall the pn of the flywheel you purchased?.....mountainman PI :D

Hvaing thought about this a great deal, I think I remember one of the things I saw that had me thinking there was a difference was that back when Yamaha still had info on the '04 model on their web site, one of the "new features" was "increased rotating mass" to smooth the power delivery. But they could have done that with the crank as easily as the flywheel. But there again, the part numbers are the same for both years. I remember hearing the info about the flywheel weight independently of that, but since I can't recall the source, we can't very well say it was reliable now, can we? :)

Anyway, I've got a couple of questions out to some people. We'll see what I get back.

so gray have we come to any conclusions yet? they just sent my flywheel from TT yesterday so it won't be here t'ill weds so i can weigh them,i'm gonna be a little ticked off if its only a +1 :)

waveraider 2000,

I just read in Motocross Action Magazine (June 2005 issue page 164) about fuel here goes...

"Fuel demand: For the umpteenth time, the majority of modern 4-strokes DO NOT need high octane gas. In truth, they don't like it."

"We use 91 octane pump gas. Stock 4 -stroke engines do not need race gas and actually lose horsepower when the octane rating is too high. Save your money for new tires."

Well there is the quote verbatim.....

I run between 91 octane to 93 octane, and my bike (2004 Yz 450f) runs great.

I think the only time you'll need to increase the octane is if you go aftermarket to a higher compression piston.

Don

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