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Buying '00 426, what to do?

By AeroSigma,
in YZ400F/426F/450F/450FX

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AeroSigma

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I'll probably be picking up a 2000 YZ426F in the next couple of weeks, and I'm planning on a top end rebuild from the get go.  I'm an intermediate recreational rider, and I pretty much stick to the forest trails (i.e. maneuverability and hill climbing are more important to me than straight-line speed.)

 

Besides the top-end, is there anything else in particular that I ought to check or freshen up to make sure the bike is performing up to snuff? Especially with the motor out anyway?

 

What about recommended mods?  I'm on a budget, but I'm not afraid to spend a little money if there's a good return.

 

Here's my list so far.

Top end rebuild

Clean and re-jet carb.

BK Carb Mod O-Ring / ZipTie / AP Spring M od

Mesh Oil Filter

Hotcams/AutoDecomp

Iridium plugs

Sprockets (13/51?)

Crankcase Breather Ho se Mod

Enigne Ice Coolant

Suspension Setup  

Kickstand

Hand Guards

General Bike Setup

 

more ideas



This post has been promoted to a wiki Edited by AeroSigma
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Hoosier-Daddy

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I think the mods that give you the best return are the ones that make it easier for you to ride.. correct suspension spring rate and valving, 9 oz. Flywheel. Gearing really depends on what you are doing. 13/52 would be good for really slow, tight trails but probably not ideal for mx tracks.

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AeroSigma

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So it seems like the Auto Decompression is very well reviewed so I guess I don't need to ask if it's worth it.

 

 Is this what I'm looking for with the "Hot Cams"?   What exactly do they do, just open up the valve timing to get a little more power?  I'm a bit unclear, Do they also do auto demcompression, or do I need to make this mod in tandem?

 

ETA: I think I figured it out, the hot cam exhasut cam comes with auto decompression, which should be they way to go if I plan on auto decomp anyway.

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grayracer513

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Dont waste your money with auto decompression. It does not make it easier to start, you actually have more control with the manual decompression. It makes it a breeze to push start if you ever get into a situation. It also comes in handy when you drown your bike.

 

This is the voice of someone who hasn't ever owned auto decompression.  I grew up riding big  British singles, and I'm completely familiar and well practiced in every technique involved with the use of manual decompression.  Let me just tell you right now, there's no way I'd give up AD for manual under any circumstance.  It would be nice to have both, because the manual setup is handy once in a while to deal with certain odd situations, but the thing is that with the pre-'06 bikes, you have the option of retaining the old system.  It absolutely does not interfere with the auto decomp at all. 

 

Starting is normally more a matter of tuning the carb correctly, mostly the idle circuit. After that, you have to get the technique right with the manual arrangement:

 

  • Find the compression stroke (push up against the "hard spot")
  • Pull the decomp lever and move the kick crank about 1-1 1/2" farther down (too far and you'll go past TDC and it won't fire; not far enough, it won't move)
  • Reset the kick crank to the top and kick through

 

By contrast, with auto decomp:

 

  • Find the compression stroke
  • Reset the lever
  • Kick

 

Or, just kick.  Works better if you do find compression and start from there, but you can just jump on and start kicking as if it were a two stroke, too.

 

And I'm sorry, but bump starting?  Don't make me laugh out loud.  There's no way the manual is easier:

 

  • Pull and hold the clutch and the decomp
  • Push or let the bike roll if it will
  • Release the clutch and let the engine start turning
  • Ease off on the decomp to restore compression (this must be done gradually enough that the next compression stroke doesn't lock the engine, but quickly enough that momentum isn't lost)
  • Pull the clutch as it fires up

Try that as you come barreling into an uphill turn and kill the engine with a brake stomp.  Or, imagine you have AD:

 

  • Push or let the bike roll
  • Drop the clutch or snap it into gear
  • Done, it's running

In the killed-it-going-into-the-turn situation, you do exactly what you would on any 250 2T; pull the clutch to free the wheel, let off the brake and dump the clutch back out to restart the engine.  Just like a 250cc two stroke. OK, a bigger, heavier 250cc two stroke, but just the same.  In fact, before my Rekluse, I could let mine roll down any slope that would produce 3 mph and bump it off every time when it was warmed up.  AD makes bump starting ridiculously easy.

 

The manual setup is definitely useful.  One quirk with the way that the AD works on the YZF is that the decompressor pin can be trapped in the retracted position in which it sits while the engine is running if the bike stalls suddenly against its own compression stroke.  In that case, without the manual release, you'd have to have the bike in gear and pull it backward just a little to free the mechanism, after which it will work normally.  With the manual setup, you'd just pull the lever once to get past that and be back to normal. 

 

At least 95% of everyone who has done this has called it one of their most worthwhile mods in terms of making the bike enjoyable to ride.  Very much worth it.

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grayracer513

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To the OP, add a couple of NGK CR8EIK iridium plugs.  The '99-'02 models had weak ignitions at starting speeds.  The iridium plug helps that.

 

As to the sprockets, 13/51 is really low gearing for that bike.  Stock is 14/49, which, because of the internal gearing differences from '05 upward, is the same as the 13/49 on the '06 and up.  If you ride mostly closed in, woodsy areas, you might like it.  But out in the desert, or more open plains areas, you'll run out of gearing before you reach a comfortable cruising speed.

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Garett0439

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This is the voice of someone who hasn't ever owned auto decompresioon.

It would be nice to have both, because the manual setup is handy once in a while to deal with certain odd situations, but the thing is that with the pre-'06 bikes, you have the option of retaining the old system. It absolutely does not interfere with the auto decomp at all.

And I'm sorry, but bump starting? Don't make me laugh out loud. There's no way the manual is easier.

To keep the manual decompression lever as well as have the auto would definitely be a plus.

I have ridden both, and have been in situations with both.

The last situation we were in was on Fordyce Creek Trail. Both me and my brother were on our street legal 01 250Fs. He has auto, I have manual.

Long story short we drowned our bikes in each of the 3 "Impassable" water crossings. Mine was much easier clear out and start with the decompression release. He ended up literally breaking off his kick start. At 125 $ for a new kick to whatever his auto dec. cam cost. Bump starting down hill in the rocks wasnt easy, but manual/auto it doesnt matter when you have momentum the bike will start.

Bump starting on flat ground is when I am thankful for my manual dec. Whether my carb is dirty, someone pumped my throttle at camp, or what have you- it is easier to push the bike on flat ground to clear it out with the compression release pulled than with the auto release. Then ease off the release and It fires up.

Under normal conditions these Yamas fire up on the first or second kick, and it really makes no difference whether you have auto or manual. Its when you get into a situation that youll wish that you had the option.

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AeroSigma

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To the OP, add a couple of NGK CR8EIK iridium plugs.  The '99-'02 models had weak ignitions at starting speeds.  The iridium plug helps that.

 

As to the sprockets, 13/51 is really low gearing for that bike.  Stock is 14/49, which, because of the internal gearing differences from '05 upward, is the same as the 13/49 on the '06 and up.  If you ride mostly closed in, woodsy areas, you might like it.  But out in the desert, or more open plains areas, you'll run out of gearing before you reach a comfortable cruising speed.

 

Thanks for the plug recommendation, I was planning on changing it out with something better, now I know what!  I will be riding closed woodsy areas exclusively (for the foreseeable future, at least) so I think I will go with the 13/51.  I suppose if I find that it's too low, I could always reduce it a bit.

 

Well the HotCams seem to be highly recommended in order to flatten out the torque, and they have ADC anyway.  Without the cams I'd probably wait and see for myself how much of a pain the manual decomp is, but I'm pretty decided on the cams anyway, so ADC is in.

 

Would you recommend Skid Plates and Radiator Braces, or are those only really necessary for racing?

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Yzf_Buz

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I'll probably be picking up a 2000 YZ426F in the next couple of weeks, and I'm planning on a top end rebuild from the get go. I'm an intermediate recreational rider, and I pretty much stick to the forest trails (i.e. maneuverability and hill climbing are more important to me than straight-line speed.)

Besides the top-end, is there anything else in particular that I ought to check or freshen up to make sure the bike is performing up to snuff? Especially with the motor out anyway?

What about recommended mods? I'm on a budget, but I'm not afraid to spend a little money if there's a good return.

Here's my list so far.

Top end rebuild

Clean and re-jet carb.

BK Carb Mod O-Ring /

/ AP Spring M od

Mesh Oil Filter

Hotcams/AutoDecomp

Iridium plugs

Sprockets (13/51?)

Crankcase Breather Ho se Mod

Enigne Ice Coolant

Suspension Setup

Kickstand

Hand Guards

General Bike Setup

more ideas

Save your money and buy a better bike. I had one and it got sold off in the first six months of ownership. It is a hard starting, heavy pig. Use the money you have plus the money you would spend on the upgrades and buy a newer 4-stroke. Just my. 02...

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AeroSigma

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Save your money and buy a better bike. I had one and it got sold off in the first six months of ownership. It is a hard starting, heavy pig. Use the money you have plus the money you would spend on the upgrades and buy a newer 4-stroke. Just my. 02...

 

Well what are your specific suggestions?  I've been going after the yzf because my understanding is that it's a relativley light bike with good handling.

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grayracer513

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"Relatively light" depends on what you relate it to.  The YZ426 is much lighter than a DR-Z or XR, but they're about 10-15 pounds up on most YZ450's.  They are nevertheless a good solid off-road bike with lots of power and low end grunt (probably a better off-road play bike than an '03-'05 YZ450), and their reliability is on a level with man hole covers, driveways, and sundials.

 

On the other hand, you can find a nice '06 or later starting at around $2000-2200 these days, and have a much nicer machine overall, vastly better forks, and the same kind of toughness, with much better parts availability.

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