YZ 426, Brand New to Me

I picked up a '00 YZ426 last weekend on the recommendation of a buddy. The bike is in wicked good condition, previously owned by a mechanic. I though it would be a good idea to go with a four stroke seeing how most of my riding will be done on tight trails. The guy fired it up for me on the first kick and rode it around and I quickly handed him $2200. I get it home and it is just a bastard to get started, an even bigger bastard after it's warm. I have never been so frustrated with a bike and it actually made me miss my CR. The bike runs extremely hot also, at one point coolant was running out of the overflow. Also the clutch isn't gradual at all, it's launchy, and if it stalls I'm screwed. I think it's fouling the plugs real bad. I don't know what to do. What changes should I make to enjoy this bike better. I want my clutch to be gradual and it to start consistantly, like any other four stroke. I love this thing and don't want to give up on it, it's wicked fast and well balanced. Any help would be greatly appreciated.

Well Firstly, put in a Hotcam exhaust cam or do the 450 cam mod (search the forum there is loads of info) it will make your bike like a two stroke to start... ie really easy. With the "launchy" clutch if you have the money put in a rukluse clutch and that will solve that problem. As for the bike overheating, these bikes like to have fresh air passing through them, i have seen a lot of people recommend Engine Ice and changing your rad cap for a higher pressure one. Do these few things and you enjoy your bike soooooo much more !!!

enjoy :)


The 200 clutch is a POS. Here's a link on how to upgrade it to 2001 spec http://www.thumpertalk.com/forum/showthread.php?t=83453&highlight=clutch+mod

The bike does not like to idle for long periods, it is a race bike and needs air coming through the rads. If its getting real hot while travelling then you should flush the cooling system, check the impeller and refill with engine ice or other suitable coolant.

As for the fouling plugs... is the bike stock? any exhaust upgrades on it? What temp and altitude do you ride at?

The previous owner might have went a bit too rich with the jetting.

Everything your having probs with we've all had also.

You'll get the starting drill, then its 2 kicks.

Yea it runs hot. Its a beast and dont let it idle too long. (Start it up in your garage then turn the lights out.)

After you stall it, try the hot start; if that doesnt work pull in the decomp lever and kick a few times, it get the fuel out. Then kick.

Fouling plugs? See Thumpertalk Search Option.

Mine starts fine. I don't need to use the hot-start at all when the bike is warm. I'm going to start using it because my KLX needs it, and I'll get confused having two different starting proceedures for the two bikes. The YZ is a bitch to kick, and getting the piston at TDC or there abouts is critical. This just takes practice.

My '01 clutch fix parts are enroute. Total cost+shipping $101.04. I've ridden a fixed '00 bike and it's well worth every cent.

The bike is not stock, Pro Circuit Ti4 exhaust, it's been rebuilt with two rides on it, The guy I bought it from raced it pretty hard on the track.

Your best bet is to pull the carb and see what jets, needle and needle position are and that'll give a good indication if its running rich. Or.... ask the previous owner.

Make sure you check the valve clearance, especially after a rebuild.

The bike is not stock, Pro Circuit Ti4 exhaust, it's been rebuilt with two rides on it, The guy I bought it from raced it pretty hard on the track.

I dont know why you hear buying a raced bike is a bad thing.

All my buddies I race with all take emaculate care of their bikes.

Race bikes typically have aftermarket parts on em too.

I guess I'd take a bike from a racer than from some bark busting noobie that doesnt know 15 hrs on the same oil isnt a good thing.


what's the hotcam exhaust cam and a new rukluse clutch going to cost me?

It'll cost a lot!!!!!

You could get the stock 2003 YZ450 cam for about $100, which is what most people on here did. Ride the bike with the stock clutch for a while and decide you like it before you make an investment such as that.

Thanks man, I'm kind of new to all this. Exactly what will the 450 cam do for me? It has an auto decomp? Any power increase? How's the installation? Compared to the effort to kick it now, will it be easier and fire more consistantly?

I fitted the hotcam exhaust cam to my bike, the main thing that swayed me towards that was the fact that the cam was designed specifically for my model bike. Where as the 450 cam mod is more of a "custom" mod that has been done, even though there isnt any reports of the 450 cam mod failing i felt better doing the hotcam mod.

I think (correct me if im wrong) the prices are as follows...

Hotcam Exhaust Cam (Auto Decomp) = $200

450 Cam Mod = $100

Rukluse Clutch = $500

Any one of the cam mods will change your bike unbelievably !!!!!! Do it you will not look back !! :)

It means you kick it like a two stroke, you can take your decom leaver off and kick it normally. MASSIVE difference !!!

i've heard the 450 cam actually mellows the power out a bit and makes it more usable as the Hotcams gives it a little more bark in the midrange. This is what I've heard as I've never ridden a 426 with either.

I have a 03' 450 cam waiting to go in once I get my cylinder and head back. I'll let you know in a few weeks.

Spot on Brandon, I have the hotcam and from what i can tell the mid range is a bit better, but i also now have the option of fitting the in-take cam at a latter stage for more low down power :)

where can I pick up the hot cam? website?

Thanks alot, I just called them, they have them in stock ready to ship tomorrow, I might just overnight it and do the work this weekend. I hope this will eleveate some of my frustration.

Dont forget you will probably need to get a couple of valve shims from your local yamaha dealer... :)

Don't know about the bikes with auto decomp, but when you kick a yzf you've gotta give it a full kick through to the bottom, not a girly stab.

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