need gearing help badly

[killer454]

i bought a 2003 yz450f for trail rideing and i have a major problem.the bike is a 4-speed and i cant seem to ride it slow enough on the trails,it wants to die on me.

it is geared to go fast i guess,when i get to a tight part in the trail the bike seems to lug and almost die from slow speed.

can anybody tell me what sprokets to buy for this bike,to give me low end for the trails.

i know i need to go down on the front and up on the rear,any advice.

i dont think i like this 4-speed trany for the trails to much.

thanks for the help everyone

 

[Bonehead]

I would try down one on the front and add two to the rear.
If you go too small on the front you have really fast wear on the sliders

 

[Ol'89r]

You have the wrong motorcycle for what you want to do. If you lower the gearing enough to ride tight trails, you will lower your top speed considerably. IMO, a Rekluse clutch may be the answer. With a Rekluse you can keep your stock gearing.

 

[helio lucas]

a cheaper and not nearly so good option is to go one down at front (maybe some up on the rear) and keep the chain ajduster free enough to fit a bigger front sprocket.
changing only the front sprocket you can adjust pretty fast you gearing, depending on the situation.
of course, you will not stop at the middle of trail to change the gearing but if you know where you are going (slow speed trail, high speed, track, etc)...

 

[whenfoxforks-ruled]

That bike? Turn the idle up as safe as you can ride it. It could be jetting/idle circuit/pilot, how are the valves, but that is boring. Vintage Bob

 

[jb_dallas]

I agree with ole89er, you simply have the wrong bike. I know something about riding MX bikes on the trail and trail riding is all I do. I had a YZ400F with the same issue, it was geared too high in first and the gears were too closely spaced. The problem is that the bike was designed for motocross racing, not trail riding. You can gear the bike down by buying a smaller countershaft sprocket and that may help. The problem is that you will gear the bike down so low trying to correct your low speed issue that you will have no top end speed. My YZ topped out at a whopping 40 mph...thats why I sold it and bought a WR, a TRAIL bike. I am much happier with the WR..gearing is right, it has an overflow tank, it has a light, etc.

 

[Matt90GT]

add 3t to the rear and a GYTR flywheel.

Other than that, if you are riding that slow you will be overheating the bike a TON. At that point either ride faster or get like a XR250 or xr400

 

[jb_dallas]

XRs are excellent bikes...bulletproof and rock solid reliable. With that being said, my XR400 I recently sold to a friend bored the hell out of me. I found it heavy and slightly underpowered. My 01 WR426 will blow away the bike in any conditions. The WRs can be made to run like hell....open the airbox and exhaust, cut the grey wire to remap the timing, and rejet. My advise is to sell the YZ and buy a WR. Or you might try a CRF450X or KTM 400/450 EXC, but it will cost you more.

 

[dirt bike dave]

For the OP, I'd be inclined to drop 1 tooth on the countershaft and train yourself to slip the clutch a lot in the tight stuff.

If that's not enough, maybe some carb tuning to mellow the low end power delivery.

It that's not enough, maybe find some cams from a WR or another year YZ (400, 426, 450) that are mellower. Lots of times the smaller displacements will have mellower cam specs.

The Rekluse clutch '89r mentioned would also be a good choice.

Just things to look into before selling the bike.

 

[mideastrider]

MX bikes make great woods bikes 4sp MX bikes not so much. Drop the front sprocket 1 tooth from stock. Front sprocket is cheap and easy to change. Make sure what stock is because it may be larger than stock now. That will give you a quick idea if you like the lower gearing or not.(it will hurt top end) If you think that makes it easier to ride you may want to go with a flywheel weight. If its still lousy in the tight stuff like others have said you may just have the wrong bike.

 

[jb_dallas]

The only problem is that the Op will spend alot of time and money trying to convert a MX bike to a trail bike. I have been there. If he wants to do any night riding, he would have to add a light. If he rides tight trails, the bike will get hot and he will need an overflow tank. If he wants any distance out of a tank of fuel, he will have to buy an oversized gas tank. IMO, it wasnt worth it, thats why I sold the YZ. It was much easier to sell the YZ and buy something intended for trail use. I know several guys who ride 2 stroke MX bikes on the trail, but that is a little different. They are A or B class guys and their skill overcomes the gearing obstacles...personally, Im not that fast.

 

[killer454]

i got a chance to look at the bikes gearing yesterday after putting in a new clutch.the bike come from california and it has a 15 front sproket and a 51 tooth rear sproket.

i do beleive this is my problem with the bogging out in tight trails.
stock is a 14 front and a 48 rear

i dont care about top end because i dont race the bike just trail ride it.

what gearing would you guys run for trails-remember this bike has the 4-speed tranny?

i was thinking 12 front and a new 51 for the back

what do you guys think?

 

[2strokerfun]

I personally try to avoid 12 on front. Smallish front sprockets tend to stretch the chain more quickly. I'd recommend you try a 13. That is a HUGE difference compared to the 15 on there now.

 

[killer454]

ok i will order a 13 for the front today.

what rear would you go with?

 

[2strokerfun]

Try what you have first and then decide where you want to go.

 

[Farmer John]

Try what you have first and then decide where you want to go.

+1

try the 13 with the 51 you have now.
If it's perfect, get a new 51
If it's too low, get a 48
If it's still too tall, get a 52

 

[killer454]

i put the new 13 front sproket on and went to the trails for a test ride and wow what a difference.
rode the bike for around 2 hours and no problem at all now,the bike performed perfect even in the tight trails where i had to slow down to a crawl.

i just want to thank everybody who helped me with this problem.

im going to keep this bike now for sure,thanks everybody