bad day - '01 426F engine seized

sorry,that really sucks.thats one problem with owning a dirtbike sooner or later [hopefully much later]its going to breakdown and its usually very costly.goodluck with getting your bike fixed.

Would that be regular mobil oil or motorcycle mobil oil?

Mobil 1 15-50 synthetic automotive oil.

It really makes no difference. The main thing is that you change your oil regularly and that it not affect your clutch, not which type or brand you use. I changed my oil after every other ride.

I will continue to use Mobil 1 when it is fixed.


Steve T

You shouldn’t feel bad about not checking for proper oil circulation after your last oil change. Your oil system was obviously working properly at that time as you rode the bike for 40+ minutes before it seized. I doubt that motor would run for more than one minute with no oil pressure, to say nothing of 40.

As for the $800+ to fix it, you could easily spend that in parts depending on what has happened. You may have some valve train damage, which will make things more expensive.

As for asking them to what to check, if this really was an oil-starvation failure, then the tranny was starved for oil also to a certain extent (although if all your oil ended up in the cases, and not out the exhaust pipe, then your tranny would be bathing in oil). I’d ask them to check all the bearings and to flush all the oil lines.

I used the same oil, and it toasted my clutch. Mine is a year older though. It didn't slip any, rather quite the opposite. It made it so grabby that I almost couldn't ride it any more. $80 worth of new frictions solved that problem. I wouldn't recommend mobil auto 15-50w to anyone. Maybe it was just my bad luck, but it is running great on regular valvoline 10-40w and no bad things happening to the clutch. BTW it is only 1/4 the cost of most bike oils so I can afford to change it after every ride. :)


Sorry to hear about your bike. My '01 426 did the same thing last Sunday. Tore into it immediately and found the lower rod bearing was seized. Ordered parts next day air on Monday from my buddies race shop here in Phoenix and we just put her back together today. Here is what I bought and what it cost, but I must add that I get my parts at close to his cost as he is a sponsor and I buy everything from pistons, riding gear and race gas from him exclusively.

Rod, rod bearing and crank pin

Piston, rings, wrist pin and clips

Main bearings and seals

all O-rings, case gaskets and exhaust seal


Cylinder honing $15.00

Crank assembly and set-up $45.00

I did the tear down and spent about 8 hours in his shop cleaning my motor and tranny parts for reassembly and helping him with fork seals, silencer repacking etc on customers bikes to free up his time to work on my 426.

Labor $200.00

So basically, even with a deal on labor and parts at almost cost, I spent a little over $800.00. I think that it would be safe to say that if you take it to a shop and touch nothing yourself it is going to run you around $1200.00-1450.00.

Fired up on the second kick! Compression feels like a Mac truck and she sounds flat-out healthy! Gonna- break her in tomorrow morning. Good luck, and if it makes you feel any better, I have to to the same thing to my RM250 next week.......she seized a main bearing (4 hours after we did it's top and bottom end!) five days before my 426 seized!

Just shows that someone always has it worse than you.........hope their is some guy out there with THREE seized bikes!

My TT brothers,

I have an '01 426F with about 125 hrs on it. It's about a year old. It is bone stock except suspension, bars, and chain/sprockets. I change the oil every other ride (Mobil 1 15-50) and change the oil filter every other oil change. I check the valve clearance regularly and change the air filter after every ride. In general, I think I have a nicely maintained bike.

Last night I warmed up the bike and changed the oil. Nothing unusual - plenty of oil in the frame and in engine. Maybe a few more flakes of metal than usual but I though nothing of it. I did NOT change the filter, it wasn't due. Since it was late at night I just poured the usual amount of oil in (1.5L) and left it at that.

Today at the track I did not check either the oil galley line for pressure or the level in the frame (but as you will see I should have). I planned on doing both during a break in riding. I rode for 20 minutes each on my first two "go-arounds." On the next go-around, I had been out for 2 laps when I stalled in a corner - or so I thought. As soon as I tried to restart, the kick starter would NOT budge. Not a bit. Hmmm. Is the decomp lever and cable/actuator OK? Yep. It was fine. After a minute or two it occured to me that it might be a siezed engine so I checked the oil level in the frame with the dipstick. It did not even register on the dipstick!

I know for a fact that I did not forget to add the oil, and that I added the correct amount (from my experience). I also checked that the frame and crankcase drain bolts were still present and they were.

My initial thought is that the oil pump somehow failed and this caused a lack of oil circulation (thus explaining the fact that there was no oil registering on the dipstick in the frame reservoir). After about 40 minutes (that's how long it took to get a buddy to bring his truck and pick me up), I tried the kickstarter again. I pushed it through about an inch and could hear a horrible grinding noise emanating from the bottom end. Arrrgh. This is bad I'm sure.

Anyway, I am comfortable doing any top end or clutch work but not at all comfortable doing anything about the bottom end so I dropped the bike off at a local race shop that I trust. They will tear it down and let me know the "good" news on Tuesday. I'll update this post then.

I do have a couple of questions though - their rough estimate is that it could cost anywhere from $800-$2000. Is that reasonable? Should I ask them to do anything else while they are in there? Look over the tranny? Do any "hop-up" work? Keep it bone stock? I am very comfortable with the quality of their work (they did my suspension and do a lot of local race setups, etc) so I am not worried about that. Mostly just wondering if I should ask them to do anything else while they are in the engine. And I wanted you all to know about it and possibly prevent the same thing from happening to you by ALWAYS checking the oil galley lines like the manual says. I just got lazy since every time I did it, it just made a mess but was otherwise fine.


Steve T

[ August 04, 2002: Message edited by: skthom2320 ]

Hick/jckmotox - Thanks for the info. That's just what I was looking for.

Extreme Diesel - I broke my bike in with Yamalube 4 20-40. I started using Mobil 1 at about 25 hours so I now have about 100 hours on it. I haven't noticed the clutch being grabby.

Now here's another question. If I'm looking at $1500 or more to have it fixed (I guess I'll know how much on Tuesday), is it worth it? Maybe I should just buy a new 2001-2002 bike, take the engine and part out the rest? I'm NOT buying an '03 though since I'd want a smoking deal. :)


[ August 04, 2002: Message edited by: skthom2320 ]

I know this is getting off topic, but I have to agree that Mobil 15w-50 worked horribly in my 426. The clutch was very grabby and it shifted lousy. In my humble opinion, you can't be Yamalube. It may be a little more exspensive, but it just works better in my 426, hands down !!!

I also use regular valvoline 10w-40 and change it VERY often. No problems yet after nearly 2 years. I plan on running the same oil in my 450. Later,


Valvoline now makes a motorcycle oil (good for wet clutches) available in 10w-40 and 20w-50. I believe it's fairly new or i just noticed it.

I also seized a 426. It only had about 60 hrs on it and the oil pump failed. The dealer only charged me parts because it was only 3 mo/old. The parts cost 900.00 this included a new cylinder. Sorry about your loss. On the subject of mobil synth. 15-50, on the search of this site, there is not any fiction modifiers and should work with a wet clutch.


I couldn't help but notice that both guys who complain of a grabby clutch due to Mobil 1 own 2000 model year bikes. The clutch in that bike is grabby no matter what oil you put in there.

I fixed mine with a Hinson basket, but a better idea is the clutch set from an '01 or '02.

BTW I have probably 100 hours on my '00 and 200 on my '01 w/ Mobil 1 synthetic 15-50 with no grabbiness or other clutch problems. IMO how the clutch is used/abused is more of a factor on life than whatever kind of oil you use (provided it doesn't have friction modifiers). But the '00 clutch is too grabby regardless. Life is too short, my advice to all '00 owners is to update the clutch (and jetting while you are at it) to '01 parts.

If you want to swap the clutch parts on the cheap, take out the one innermost friction plate and replace it with the plate combo from the 01. The clutch throw will be a little off, but works fine and you'll get used to it. Elsewise you have to swap the actuation arm parts too.

Ummm... nope, I don't think so. The clutch was fine before the swap to mobil, and the new one is perfect. Maybe the 00 clutch was different, but it did not like the mobil at all. I replaced the frictions with ebc (I think) and it works extremely well. :)

I just had my new valves and bottom end done for 1500 bucks at a local shop the piston and rings were fine.

Originally posted by Extreme Diesel:

Maybe the 00 clutch was different...

There is no maybe about it. Do yourself a favor and swap the '01 parts in there as described above next time you service it. Makes a world of difference.

I noticed zero difference in clutch performance when I switched from Yamalube to Mobil 1 on my '00, but I rarely fan the clutch.

skthom2320, it would be a good idea to thoroughly flush out the oil tank in the frame, just in case. Also, remove the large nut on the bottom of the down tube and clean the screen.

Originally posted by Scott F:

[qb]skthom2320, it would be a good idea to thoroughly flush out the oil tank in the frame, just in case. [qb]

With what?

[ August 05, 2002: Message edited by: skthom2320 ]

I'll give it a try next time I have it apart. What parts do you replace? Just the plates, or what?

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