YZ450F 4 Speed Trans Questions


18 replies to this topic
  • LemonDrizzle

Posted May 15, 2011 - 05:27 PM

#1

I'm riding a YZ250 at the moment but am looking at buying a 4 stroke. I found a 2003 YZ450F for a really good price but have noticed that from 2003-2005 the 450's have 4 speed transmissions. I guess what I am trying to figure out is how a 4 speed trans will work out riding MX compared to a 5 speed. Most of my riding is MX with some SX and most of the jumps on the MX tracks are 3rd gear jumps. What I'm worried about is with a 4 speed trans am I going to be floating between being really high in 2nd or really low in 3rd all the time.

Thanks

  • Bobbed06

Posted May 15, 2011 - 06:08 PM

#2

I rode KX 250s from 99-02 and just bought a MINT 03 YZF 450

I was only able to ride it for a few minutes because the old fuel and the carb was clogged but in the short time I rode it, I felt like it rode like the KX tranny without the 5th gear. Since I always holeshot on the KX by starting in 2nd gear anyways I am gonna use a smaller rear sprocket on the YZF to make the gearing a bit higher. I dont think the 4 speed is gonna be great for off road due to the limited gear spread, but when Tim Ferrry raced the 5 speed 426 in 02 he removed the 4th and 5th gears making it a 3 speed.

On my KX I only used 2nd,3rd,and 4th rarely ever using 1st or 5th. I see in your sig that you have a 99 KX250 and a 00 YZ250 which is the same bike my buddy raced as well. When I rode his YZ in comparo to my KX his felt like I was riding on the front wheel. My KX felt like the front end was much less weighted. This YFZ feels right in the middle of those 2 bikes. I think I am gonna like this YZF :smirk:

  • mikedabike

Posted May 15, 2011 - 08:20 PM

#3

I had a 04 and now have a 07. I prefer the 4 speed. Bike has plenty of torque to pull it around less shifting means conserving energy and faster laps.

  • proz07

Posted May 16, 2011 - 06:42 AM

#4

just look up the gearing for these bikes all they did was pull 5th gear out the ratios are still the same. And if you really need to make it a better woods bike later on or something you can swap out the trans to a 03-06 wr450 5-speed which will give you a usable 1st and ADD 5th gear OD. I believe for MX you only ever need the 4-speed.

z

  • grayracer513

Posted May 16, 2011 - 09:00 AM

#5

just look up the gearing for these bikes all they did was pull 5th gear out the ratios are still the same.

Not exactly. 1-3 are fairly identical, but 4th is a different ratio in the 4 speed trans that is in between where 4th and 5th are in the 5 speeds. The 4 speed is only a minor handicap in off-road or desert riding, and not a lot different than the problems with using any close ratio MX 5 speed in those conditions. For MX, it's not a handicap at all.

  • bryawn

Posted May 16, 2011 - 08:27 PM

#6

I just got an '04 YZ450 and rode it for the first time this past weekend in the woods. First gear is a little tall, but the top end is more than fast enough for gravel roads. The bike has so much power and torque it hardly matters what gear you're in -- and it pulls solid wheelies in third or fourth gear going 60 or so. Fun, fun fun.

For some gnarly technical climbs I was using the clutch a lot, but really it's fine, and no doubt the gearing is perfect for MX or GPs. I have a 13 tooth front sprocket, but I'm not seeing the point right now.

  • jasen 2007

Posted May 17, 2011 - 07:52 AM

#7

i have an 05 and 06 yz450's. We do mostly free rides, woods riding and some mx. I find the 4 speed to be more suited for my style. I don't think you would be disappointed either way.

  • LemonDrizzle

Posted May 17, 2011 - 06:43 PM

#8

There seems to be a lot of good feedback both here on TT and other places so I'm not too worried about the 4 speed tranny any more. The other issue I have to think about though is the hit that the 03-05 YZFs have. I've seen a lot of people saying that those bikes are monsters and the low end hit is pretty radical. A lot of the tracks I ride on are hard packed clay so I'm really looking for something that has smooth power delivery to cut down on wheel spin and still be able to get out of corners quickly and accelerate to the jumps well. Plus I just want something that doesn't give me so much of a workout to ride.

  • grayracer513

Posted May 17, 2011 - 08:00 PM

#9

I've seen a lot of people saying that those bikes are monsters and the low end hit is pretty radical. A lot of the tracks I ride on are hard packed clay so I'm really looking for something that has smooth power delivery to cut down on wheel spin and still be able to get out of corners quickly and accelerate to the jumps well. Plus I just want something that doesn't give me so much of a workout to ride.

The '03 hits hard. The '04 nearly as hard. The '05 was over compensated and soft by the accounts of many, but many others find it to their liking. The difference is in the CDI's, and you might find your ultimate answer in a Vortex CDI box.

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  • Bobbed06

Posted May 17, 2011 - 08:50 PM

#10

There seems to be a lot of good feedback both here on TT and other places so I'm not too worried about the 4 speed tranny any more. The other issue I have to think about though is the hit that the 03-05 YZFs have. I've seen a lot of people saying that those bikes are monsters and the low end hit is pretty radical. A lot of the tracks I ride on are hard packed clay so I'm really looking for something that has smooth power delivery to cut down on wheel spin and still be able to get out of corners quickly and accelerate to the jumps well. Plus I just want something that doesn't give me so much of a workout to ride.


My 00 and 02 KX 250 hit harder than my buddies 00 YZ250 and this 03 YZF450 hits much harder than either of my KX 250s did. You may want to choose one of the smoother later years if you are looking for slick clay track capability. Especially if they run quads in between your 1st and 2nd motos. Those things are traction erasers :smirk: I cant wait to get my YZF serviced up and ready for track duty.

  • LemonDrizzle

Posted May 22, 2011 - 08:58 AM

#11

The '03 hits hard. The '04 nearly as hard. The '05 was over compensated and soft by the accounts of many, but many others find it to their liking. The difference is in the CDI's, and you might find your ultimate answer in a Vortex CDI box.


The Vortex CDI is an interesting idea, but at $400 it's pretty expensive. That's not to say that I wouldn't buy it in the end, but if I could find one used for a decent price then I would probably do it for sure. Would it be possible to swap the CDI to a later model factory CDI or is that out of the question?

  • grayracer513

Posted May 22, 2011 - 12:44 PM

#12

I believe that the CDI's from later bikes will fit and function, I jusyt can't say for certain. The '06 is the most popular one, but they're such a hot fix for the '08-'09 models that demand for them has driven the price of used ones way up. Might try an '07, but I'm not sure the effect it would have on and engines with the older cams.

  • LemonDrizzle

Posted May 22, 2011 - 01:57 PM

#13

Thanks for the info grayracer. I think that just knowing that there are options available for what I am trying to get out of the bike may be enough to make me pull the trigger on buying it. The bike I am looking at buying is a 2003 YZ450F and the guy is asking $1800 obo so I'm hoping I can get it for $1600 which to me is a good deal. Plus the guy just replaced the original rear tire so I'm thinking the bike doesn't have too many hours on it and if it does they are easy hours.

  • 98WR400F

Posted May 22, 2011 - 10:07 PM

#14

i have an 05 yz450f that i did some cdi swapping on to get a little more hit out of the snap of the throttle. i put an 04 box on it and snapped rite on. if you are lookin to calm the nasty hit of the 03 look into a 05 unit. the 05s make plenty of power and have a nice smooth powerband that just keeps pullin without the harsh hit of the 03-04s and will work with the cams you have very well as the 05s are very similure. and i love the 4 speed tranny!

  • grayracer513

Posted May 23, 2011 - 06:09 AM

#15

a 05 unit.... will work with the cams you have very well as the 05s are very similure.

The '05 cams are not similar, they're identical.

There are essentially two camps of opinion about the '05; one group who rode the '03-'04 models, or another 450, or a strong 250 2T, before they rode an '05, and another group who hadn't ridden a 450 prior to the '05 YZF. The second group were generally accepting of it, and thought it smooth and powerful. The former group were almost universally disappointed in it. It might be just what you want, though.

One alternative combination might be to find a set of '06 cams, or even '07's and use them with the '03 or '04 CDI. The cams in the later units are biased more toward top end than the earlier ones, and that might have a softening effect without a big loss of mid range.

  • LemonDrizzle

Posted May 24, 2011 - 03:04 PM

#16

The '05 cams are not similar, they're identical.

There are essentially two camps of opinion about the '05; one group who rode the '03-'04 models, or another 450, or a strong 250 2T, before they rode an '05, and another group who hadn't ridden a 450 prior to the '05 YZF. The second group were generally accepting of it, and thought it smooth and powerful. The former group were almost universally disappointed in it. It might be just what you want, though.

One alternative combination might be to find a set of '06 cams, or even '07's and use them with the '03 or '04 CDI. The cams in the later units are biased more toward top end than the earlier ones, and that might have a softening effect without a big loss of mid range.


I'm getting the impression that making this bike run like I would want it to would not be hard to accomplish. Things are looking up.

  • danzick

Posted May 24, 2011 - 04:38 PM

#17

i have an 04, i ride in the mountains hill climbing a lot, and do around 4 or 5 dunes trips a year. thing works decent in the dunes for only being a 4 speed, and the power is awesome. it has really strong power for messin around in the woods and doing big climbs in the dunes. beware, my 4th gear went out, and i am currently in the process of finishing up putting the motor back together. ive heard from people that its common in the early 450s?

  • LemonDrizzle

Posted May 25, 2011 - 04:57 PM

#18

i have an 04, i ride in the mountains hill climbing a lot, and do around 4 or 5 dunes trips a year. thing works decent in the dunes for only being a 4 speed, and the power is awesome. it has really strong power for messin around in the woods and doing big climbs in the dunes. beware, my 4th gear went out, and i am currently in the process of finishing up putting the motor back together. ive heard from people that its common in the early 450s?


Lucky for me, I rarely use 4th gear. All my riding is on tracks and pretty much everything calls for 3rd. About the only time I use 4th is riding the connector trails between tracks.

  • danzick

Posted May 26, 2011 - 08:10 AM

#19

lucky, i do mountain riding and dunes riding so i use 4th a lot. it wasnt a very fun process. hopefully i get it all back together right.





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