YZ426 Tips


You will have a great time on the bike. Adjustment shouldn't take long. The bike jumps really well, handles whoops great, and the weight is not too much of an issue once you're riding. The most important thing to remember when jumping is to leave the throttle on until you're off the face of a jump. If you don't, the compression braking will make the front wheel dive and it will not be fun. Everything will just fall into place as you get some seat time on it. The starting is really quite easy once you get the routine down.

Your buddies may be laughing now hahaha...but wait til you fire the 12.5:1 compression beast up they will be scared out of their minds (especially when they see the glowing red header pipe :) ) And on top of that they havent seen roost until they wander into the 426's wake of roost (all you guys know what im saying :D ) Im sure you will adapt to the 4 stroke fairly well it will probably be hard to start at first...but once you learn the drill (i wont repeat as im sure you have heard it 101 times) it is easy to start! Buy 2 extra plugs just in case you foul it at the track trying to get used to starting it (buy the CR8E's they are better than the 9's) I would also get an extra oil filter (they are 5 bucks) im saving for a stainless one :D Anyway hope you like your new bike!



I get my kicks on a 2001' YZ426!

Friendswood, TX

Originally posted by motoman393:

I would also get an extra oil filter (they are 5 bucks).

Where’d ya find a five dollar filter? I’m paying $10.


You can backflush and reuse the filters, they are made of steel and the little rubber seals wear out long before the element. However if I notice any amount of visible metallic debris (and you will) I toss ‘em.

One thing I’ve noticed is that when I climb back on a ring-ding I am suddenly struggling with a severe nose-up attitude over jumps. Once I correct that and get back on my 426 its nose down. I’ve seen others do the same thing. I will say that letting of the gas in flight does NOT approximate stabbing the rear brake, although perhaps a bit of in-air engine breaking explains the phenomenon I described above. If you’re in to whip-its be careful with the thumper. Once whipped it tends to remain so.

Other stuff:

On this bike the clutch is not a “keep the revs up” lever it is the “Ohmigod don’t stall it now” lever. Use it accordingly.

The idle mix is adjusted via a fuel screw (not air screw) so out is richer, not leaner.

Do not test the rev limiter from inside your garage after that 8 beer happy hour. Neighbors and cohabitants will not appreciate this (although you will).

Buy some grease with your bike because there probably won’t be much on it. In fact, many guys here would recommend you grease the linkage and steering stem bearings BEFORE you ride it. I’m not naïve enough to think you can restrain yourself (I couldn’t) so I’ll recommend you grease it before you ride in any wet stuff.

Change the oil and filter after each ride (not just type A guys) for the first 5 rides and remove and clean the oil strainer screen at the bottom of the in-frame reservoir a few times. You will likely be horrified by what you find. In advance let me say, “Relax. That’s normal.”

Beware of the dreaded “Carbon Fiber Fixation” and “Titanium Temptation” that attacks many new YZF owners. You may consider hiding your credit cards from yourself. I’ve got my # memorized so its too late for me.

Yamalube is a bit of a rip off. You may want to buy a case just to be generous but once that is used up switch to Mobil 1 car synthetic 15-50W.

But the biggest thing that you will have to get used to is throttle control. For your first few rides I’m sure you’ll notice that if you snap the throttle on too rapidly the bike may hesitate or stumble. I recommend trying to ignore this until you become accustomed to the bike to avoid trying to fix a problem that isn’t there. Once your new scoot has broken you in you’ll be better able to determine whatever jetting that works best for your conditions. Come back to Thumpertalk for jetting tips, just search all of the James Dean (or Clark Mason) posts for the letters “DTM” (I just did this and got 25 matches :) ).

sorry hick they are 10 bucks whoops :) I was thinking about my XR400 filter they were 5 bucks a pop! Still getting used to this beast! lol



I get my kicks on a 2001' YZ426!

Friendswood, TX

Hey guys. I just ordered my first thumper (2001 YZ426). I'll be picking it up in late February. I was wondering if you guys had any suggestion or tips that would make my switch from 2 strokes to 4 strokes any easier. How are they on take-off? Because of the compression braking, does chopping the throttle in mid-flight have the same affect as tapping the rear brake? How are they in whoops? Aside from normal maintenance, is there anything I should keep an eye on? I know the compression braking, the weight and especially the starting are gonna be major concerns. I appreciate all your help. I have a feeling I'll be calling on you guys a lot. All my buddies are 2 strokers and they're giving me a good teasing about buying a thumper. They even have a bet going about how long it will take me to get the beast fired up.

I totally forgot to look when I was in the showroom last weekend, but does the 426 have zerk fittings on the linkage or is this a take it apart to grease it type of ordeal? Also, which grease do you guys (and/or yamaha) recommend?


It won't let me delete my post so I wiped it out. Please disregard.

[This message has been edited by Boit (edited 01-09-2001).]

There's not a zerk fitting on this bike. At least you will become a good mechanic. You'll need a good torque wrench. Any good quality waterproof grease is what's called for. Bel Ray and Silkolene are good examples.

I can only vouch almost verbatim for everything Hick has mentioned in his reply. Your 2-stroke buddies will soon regret your choice of new bikes, believe me!

Hey guys, where exactly is the oil strainer screen at the bottom of the in-frame reservoir? I have '98 YZ400 and assume that it has one of these??? Also, does the manual call out the torque values for the linkage?

Paul in AZ


The combo. pipe/hose that delivers oil from the reservoir to the pump (just under the filter) attaches to a fitting (with a clamp on the hose end) that threads into the reservoir just above the uppermost skid plate bolt. The screen in question is on the other side of this fitting, inside the reservoir. I think it needs a 24 mm wrench or deep socket. It is an aluminum fitting that got painted and can be stubborn to break loose. I needed an air impact to dislodge mine the first time, but I’d recommend you have a look at it. It is fairly large and I’d be surprised if one ever got completely obstructed, but if it did your oil-starved motor would be toast in short order.

The manual does list torque spec.s for the linkage, in more than one place. Values are listed on the exploded graphic next to each fastener and they are listed again in the following pages that give detailed R&R instructions. FYI the lower shock bolt, which threads into the linkage cam, backed out and almost destroyed the pull rod on my ‘00. Loctite is your friend where locknuts are not used.

BTW, I’m sure you know this (or would figure it out) but where locking nuts are used measure the torque applied on the nut and not the bolt. I seem to remember some of the spec.s in the manual referring to the bolt. If you only take a reading at the bolt you may leave things undertightened.

Okay then, I was just checking.

[This message has been edited by Hick (edited 01-09-2001).]

Hick is so right about the shock bolt. I had one back out on a previous F, and it deeply gouged the wishbone link. You must loctite and torque the lower shock bolt.

I need some answers and help.. I recently bought a used 98 YZ400, Whe I bought it the bike had a very loud engine knock so I took it to the shop and asked them to check the water pump and the valves. It ran fine and very strong but was just noisy. They went throught the motor and told me I had to replace the crank, connecting rod, cam chain, and piston... $1200 later I got the bike back it still made a similar noise but a little quieter. I put about 3 hours of break in on the bike, then I changed the oil, filter, air filter and flushed the radiator. Then I went riding again and road for about 20 minutes when while coasting the bike just died. When I went to restart the compression stroke could not be found. When you kicked it you could feel some compression but it blew back through the carb and nothing through the exhaust. I immediately loaded it up and took it to the shop who did the repairs. They have since called me to say that 2 or all three intake valves are bent and need replacing due to my over reving the motor. I told them I did not think that possible and even if it was I asked what about the rev limiter why it had not kicked in? The service mgr replied it does not have one and that the repairs were not covered because it was my fault and had nothing to do with the work they had just performed. Is this true, does this thing not have a rev limiter? Is there anything I can do to get the shop to help work on this? They are the only dealer in a town of 400,000 so they do not seem to care too much about service.


Tom N.

Tom, sorry to hear about the mess. There is a rev limiter. My understanding is that you cannot overrev it by applying throttle. You can overrev it by downshifting. If you are motoring along in 4th, pull in the clutch, shift to first, and drop the clutch-that is how you can overrev it. I think you dealer is taking advantage of you, find another, even if you have to drive further.


Your bike most certainly DOES have a rev limiter, I believe at 11,200 rpm or thereabouts.

I don’t think overreving alone would cause any chance meeting of piston and valve either. IMO your cam chain let go or a sloppy install caused the problem.

You need to find some way to make them take responsibility for this because based upon what you have posted it is clear to me that they are at fault. I mean, come on, they just had the motor all apart, it grenades a scant few hours later and they claim rider abuse? Sounds like horse poop to me.

Dang, this is pissing ME off and its not even my bike…

Try to be nice and inform this goombah that you know for a fact that this bike has a working rev limiter and that since you instructed him to check the valves and he replaced the cam chain it is clearly not your fault that this happened (notice we ain’t saying it’s HIS fault, just that it ain’t yours). Then ask him what exactly, since we’ve now ruled out the over-rev, you failed to do that you should have that would have prevented this from happening (we both know the answer is USE A DIFFERENT MECHANIC but keep that to yourself). If this line of reasoning doesn’t work I don’t know what, short of violence and wholesale verbal abuse, I would resort to make this jerk acknowledge the obvious.

I feel your pain but try not to lose your temper, that may be momentarily fulfilling but probably won’t help your cause any.

Tom N, First of all, I'm sorry to hear of your bad experience with your bike and dealer so far. I also mirror the sentiments of the other members who have responded to your thread! This kind of stuff burns my ass also! When your dealer placed the blame on you, did you explain to him that the original noise still remained after THEIR work and that the only riding you had done since was just three hours of break-in which does not include revving the motor past 11,000 or anywhere near that!? Did they give you any instructions on how to break-in the motor following their work? Just food for thought when you go back to make your case with the other info you got in this forum. I think you have a case for debate with this shyster but it may boil down to your word against his. I hope this is not the case. Good luck!


I want to give a big THANK YOU to Mike and Hick for replying to my posted problem.

I followed your advice and went down to the shop where they had just pulled the head off my bike and found 1 intake valve had bent. We talked about it for a few minutes and they acknowledged tht it did infact have a rev limiter and that I didnt cause the problem by over reving. They would not admit that they had done anything wrong (like not shimming that valve correctly like I think)but did agree to replace the valve and half the labor with me. It's not quite a free repair but it was better than nothing. I asked to look at the piston to check for damage and did not see any, there was a visible mark (no ding or scratch)in the carbon on the piston head where the valve had touched. I asked about replacing all the valves since we were in the neiborhood but they said the others were ok. Was this wise advice? I appreciate the quick help on this one and it certainly saved me a few $$ I will visit this site often and will use when ever I have a problem. Thanks again for all your help!!! :))


Tom N.

More pissy ass, mindless banter cop-out excuses from Dealers - they make me puke. I'm with Boit on this one too! Get yourself set-up with the mic-fish and always check prices against the dealer's. About 1 out of 10 times the dealer may come close to what you can track down on-line.

I really hope you get that dealer to take responsibility for what has occurred here.

I picked -up my bike last June - I took it back because it would not accept throttle and cut-out severely. The dealer and the Yamaha rep on-line denied the problem. To show futher ignorance, the dealer mechanic answered my (playing dumb)question as to the whereabouts of the filers (screen and Filter) - as "these bikes don't have any". O.K. thanks - give me my bike back and I'm out of here.

Long term - there are some of us who will have to maybe pull the engine and send it off to a tech shop - to completely avoid the dealership - that is what I plan to do.

I am starting a thread to elicite GOOD reputable hi-tech shops that can do overhalls if necesssary. It's my next up.

For now though...

I'm rubber down and rippin ruts!!!!!!


Take what you can get I guess.

Meanwhile let’s try and figure out why this happened to begin with. Improper valve timing? Worn or improperly installed chain guide(s) and tensioner? Bad or worn valve spring? Broken retainer?

Maybe you should take your bike to another mechanic as soon as the first is done with it and have them give the valvetrain the once over (check retainers, spring tension, chain guide & tensioner, clearance and timing).

I wouldn’t worry about the piston unless the valve took some material with it or left a sharp edged gouge. But ask them, ever so innocently, whether you got new main bearings. You should have when they replaced the crank.

Hope this helps!

Now that the dealer has admitted that the overrev was not your fault, you might try writing a letter to Yamaha. Tell the dealer that is what you are going to do. I bet they end up paying for it. By the way, post the name of this dealer so at least no one else here will give them any business. Best of Luck.

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