426 Maintenance Question

First let me apologize for my ignorance on this subject...

I just bought an 02 426 and love the bike. I have been away from the dirt bike scene for a long time and forgot how much maintenance you need to do on these bikes. I read through the maintenance intervals and it seems like I will spend more time working on the bike than riding it.

As a kid all I did to my bikes were change the oil and clean the filter, change the spark plgs and lube pivot points.

Now I read how the valves need to be checked every 3 rides and take the engine apart every five rides for the cams, pistons and cylinder head.

What really needs to be done in this area and how would you define 3 to 5 rides. Assuming I am going to the track 2x's a week and riding(not racing) for 2-3 hours. Do I really need to be taking the engine apart every week and a half?

Thanks in advance for your help.

I use mine for MX only and my schedule goes something like this....

oil change after every three events

oil & oil filter after every six

I've never been two bothered about the actual number of 'hours' between each change...life's too short :)

If the racing has been particularly hard or long, I might cut this down to oil every 2 and filter every 4.

Ride it and enjoy it - treat it like the piece of metal it is.....

Welcome to TT, and to the Blue Side...

I think you have misunderstood the maintenance intervals... You may want to follow the oil change schedule some people have, but that would be the only thing you would have to do every 3 to 5 rides besides the usual airfilter cleaning and chain lubrication.

Valves should be checked at say 500 miles, and a lot of people have reported 1,000s of miles and the valves were still in spec. One of the advantages of the 4 stroke over the two stroke is the lack of things like top end rebuilds every 20-50 hours. Many people here are on their original sparkplug... in fact, some have rusted in place!!

Your maintenance schedule will basically be:

1. clean and oil airfilter every 8-12 hours, or at the end of the day if it's been a big, dusty day. Easiest solutionis to keep a spare on hand, oiled, ready to go... you can use filter skins to extend the interval if need be

2. Wash your bike after each days riding, but no pressure washing - simple green gets the vote here on TT as the best product.

3. Lube your chain and check it's tension after each washing session, or go to an O or X ring chain and get longer life from your sprockets.

4. you will have to lube the headstem bearing, and the swingarm/lingabe bearings, as well as the wheel bearing. Do it this weekend. Then depending on use and prevailing conditions, do it once or twice a year. Install grease fittings and the next time it will be a 5 minute job.

5. usual other stuff like nuts/bolts, spokes, cables etc, on a monthly basis, clean, check and oil as appropriate. Check for scoring of the forks sliders - or get some seal savers to help there...

You may want to check your plug from time to time to see if your mix is right, but riding the bike should tell you that anyway...

Simple stuff mostly, and then you will be rewarded with a long and fruitful association with your blue mistress...

For more specific answers to individual things, use the search feature here... and if you have the manual, then read it - it is very good as far as manuals go - if not, get one from the dealer... though all new bikes should come with one, so ask the dealer... Yamaha have pretty conservative maintenace intervals, but they are only trying to protect themselves, right? :):D



[ July 05, 2002: Message edited by: yamaha.dude ]

Many thanks for the insight and advise. This is very helpful and I feel much better now. I do have the manual and it shows for example..."every third (or 500 KM)" as a maintenance interval and does not specify if it is 3 rides or 500KM for the specific task. I do not know about you...but I am not putting 500KM on my machine every 3 rides.

One last question regarding the valves...the dealer said to take it back to them after break-in to get everything checked out and re-adjust the valves. Everything appears to be running perfect. They charge about $300+ for this...I was planning on doing everything myself, except have the shop check the valves. Is this stll necessary to have them work on this valves only after 10 hours of riding?

Let me know your thoughts. Thank you again for the help!

After break-in, check the valves yourself. If they are out of spec (probably not) then reshim yourself or have your dealer do it. After break-in I check valve clearances twice a year. Never been out of spec.

Originally posted by CJ_Baran:

One last question regarding the valves...the dealer said to take it back to them after break-in to get everything checked out and re-adjust the valves. Everything appears to be running perfect. They charge about $300+ for this...I was planning on doing everything myself, except have the shop check the valves. Is this stll necessary to have them work on this valves only after 10 hours of riding?

Let me know your thoughts. Thank you again for the help!

It is your money, but I wouldn’t even consider paying anybody $300 to look at my bike and maybe take off the head cover to check the valves.

I’m sure the vast majority of us here don’t even bother to look at them until at least 20 to 30 hours. In my experience (two of these bikes) the valves will need to be reshimmed at about 40 to 60 hours. It may seem a little intimidating, but it is a very simple thing to do and requires no special tools other than a torque wrench and feeler gauge (one w/ bends in the end work best). Just follow the manual.

Way before I get to the 40 hour mark I check the clearance and pull the valve buckets and write down the shim numbers, that way when they start to go out of spec I already know which shims to order. Something to consider…

Hope this helps.

CJ, Nobody has brought up the issue of 1st oil changes. It seems Yamaha does not spend too much time on cleaning out chips during mfg. Change your oil, clean oil screen every time for your first 3-4 rides, you will be amazed at all the crap you get. It's actually scary.


I'm with SoCal on the initial oil changes. Buy a magnetic drain plug, it catches alot of stuff also. I had to go about 5 rides and 5 oil changes till the stuff started to come out acceptable. Remember to clean the oil filter each time also. The filter in the frame on both of my bikes have never had anything in them so I wouldn't be too concerned about that one, you may wanna look at least once though to make sure Jimmy Hoffa ain't in there. Something else to really pay attention to are the spokes. After each ride, check them, you'll find at first they will be pretty loose. Keep at em' for the first 5 rides atleast and check them periodically afterwards. Don't run your chain too tight or you'll be sorry. About 2" is the tightest I run mine. You should also grease the suspension linkage soon after you get it, none of the manufacturers put much grease on any of the bearings. Use a good waterproof grease. The stock chain won't last long, so go with a good O or X ring chain as previously stated or you'll be buying sprockets as well. When you wash it, put a golf tee in the hole on the right hand side of the cylinder to keep water out or your spark plug will get some pretty serious corrosion on it. Every once in a while I squirt some WD-40 in there to displace the water.

On my 99 YZ400, I had 2 hard years of riding on it and decided to do the top end on it. After pulling it apart, I found it was in great shape and at most, the rings were worn but still within specs. Use a good quality motor oil and change it often and you can expect the same longevity.


02 YZ426

99 YZ400

I'm in total agreement with Hick. As long as you have a modicum of mechanical ability, you can check the valve clearance. All you are doing is checking a small gap between the cam lobes and buckets with the engine at TDC of the compression stroke with engine "cold".

Also, I suppose I am extremely anal as I change my oil and clean my Scott's filter after EVERY ride. Personally, I enjoy wrenching on my machine nearly as much as riding it. I would hazard to guess that I put in 3 hours of work for every hour of saddle time. The result is a bike that remains fresh and tight....plus, I've never suffered a DNF due to mechanical failure.

[ July 06, 2002: Message edited by: Boit ]

check your clutch plates regularly too, the last thing you want is having a clutch plate blow up and clog the oil filter up, and sieze your engine.

it also helps to pick up a 20$ hour meter from a power-equipment dealer.

Many thanks for all your valuable insight! I be working on my bike this weekend!

Cheers. :)

hey cj,

although the 250F FAQ is geared towards, you guessed it, yama's 250cc models, there is a lot of useful info in it which you can apply to your bike as well. for example, my oil change proceedure writeup is 100% applicable to your new bike.

the 250F FAQ (maintained by sean/z4me):


the oil change procedure:


by the way, i don't know where you got this "tear down the engine every couple of weeks" info, but... one of the nice things about owning a four stroke is *not* having to see the motor internals for a long time. i'm a casual off road/trails rider (i've got about 1000 miles on my '01 WR250F) and i've no plans of taking the motor apart again anytime soon (note that i only had the cam cover off to change the timing from WR-spec to YZ-spec). by the way my valves are still in spec, with the very same set of shims that the factory put in. and fellow TT'er steve unruh (sunruh) had >2500 miles of Texas harescrambles on his YZ250F before he tore into the guts. and not surprisingly, there wasn't too much to look at in terms of wear.

so, regarding maintenance, there are three things you should concentrate on:

1) change the oil (it's shared between the engine and clutch so it's getting beaten on twice) [takes 10 minutes every 50-100 miles or so]

2) lube your headset bearings [takes 45 minutes every 2-3 months or so]

3) lube your swingarm/shock/linkage bearings [takes a couple of hours every 3-4 months or so, but more often if you ride in lots of mud/water/sand]

for info on this see, for example,


have fun and good luck with the new bike!

jim aka the wrooster

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