DirtRider Mag Article - Top End Every 60 Hours?!?

As a new owner of a 05' WR450, I was pleased to see a series of articles by "Dr. Dirt" relating to new gen 4-stroke engines in this months Dirt Rider magazine. He outlines some "gotchas" with different years and models. Anyway, he goes on to say that a 450 class engine should have the top end rebuilt every 60 hours.

Does this mean my new bike with 15 hours on it is already 1/4 used up? By the time summer hits will I have to worry about reliability? I don't race, rather do light trail riding and ride it to work a few times a week.

I'd be very interested to hear the opinion of this group....

Do you rebuild your top end every 60 hours?

If not how many hours do you go?



95 KLR650 (for sale)

03 YZF600R

05 WR450F

I think it all depends on how you ride and how often you adjust your valves and change your oil.... I call BS on 60 hours.........

sounds like a bunch of BS to me

I have a 00 WR400 and a 03 WR450. I have 7500 trail miles on the 400 and 3500 on the 450. Compression tests on both show the same as when they were first broken in. I keep the air filters clean, the valves adjusted to the loose end of the specs, change the oil and filter every 3rd ride, and use a full synthetic oil. I don't moto anymore at all. I will do a top end when I see a measurable drop in the compression test. So far so good. Not sure how this relates to the 05s FWIW. :cry:

My 2003 YZ450 has about 100+ moto races on it. Original piston, rings, top end... valves adjusted regularly, oil changed with Yamalube4 only.. There has been no loss of power or any problems..

Your motor should be bulletproof if you take good care of it. :cry:

Oh, and I think that the article in DirtRider is exaggerated a bit... I mean ... A lot.. IMO :cry:

yet another reason dirt rider sucks!!!!!! it is full of bad info and corporate suck up articles :cry::cry::cry::cry:

Didn't Eric Gore write that artical? Enough said!

:cry: LOL.my 99 WR400 is still on ALL the original top end, at a recent dyno session it was still making 45 at the rear wheel.......I hate to think how mwnayhours it has on it..its been Super moto'd for street use as well ! :cry:

And this one time in Band Camp..................

if you were racing at pro level and every 1/4 hp counted, then you would be doing a freshen up even few races. I think honda specify to replace the piston every 15hrs :cry: on the 450 and kwaka/Suzi say 5 hrs for shims on the 250! :cry: Just ride it! I do oil/air filter filters every 5 hours and check the shims and clean the oil filter every 10. Do this and she'll go for ever.

If you head is in good nick, you could extend the shim checking a bit, but I do mine more frequently as I know my centre inlet is on the way out.

I got 600 hours on mine. 4 valve adjustments. Over 11,000 miles. My motor is dead tired and was rattling like a time bomb on the last ride in mid December. It is now apart and being completely rebuilt.

I got 600 hours on mine. 4 valve adjustments. Over 11,000 miles. My motor is dead tired and was rattling like a time bomb on the last ride in mid December. It is now apart and being completely rebuilt.


Just a quick highjack, Are you going to supersize the bore? I remember reading earlier that you were contemplating going bigger come rebuild time. Just curious.

99mm piston for a 490 size with a 12.5:1 compression ratio.

Kibblewhite SS valves etc.

I am looking to build a low reving tractor.

Only thing I missed this time is the Falicon heavy stroker crank due to delivery issues. Next time I will be prepared! :cry:

I have 220 hours on my 03 WR450. Thats with an hour meter installed from day one. I do change oil and air filters, I have a Scott's oil filter and just clean it and put it back in. I run my bike a tad on the rich side for smooth mellow power. In doing this my valves last longer, but two adjustments in 5500 miles of all types of riding sold me. The quick snappy power and endless jetting guys cant hang on long enough to use all of that power anyway. Now when racing I want a solid engine under me, it will be abused and I don't go not to finish. Normal guys with a little maintenance always seem to go farther, just look at how many thousands of miles some of the Thumper Talk members have. Heck my bikes flywheel was supposed to self destruct but I never had a problem! I think it would be more interresting for Dirt Bike to do an article on how far a engine can run thats maintained!

Hey, Desracer, an hour meter sounds like a really worthwhile mod for any dirt bike that doesn't have an odometer. But I don't hear much talk of using them. Where do you get one? Who makes it? What do they cost?

How does it connect? I would think it would be a pretty simple device; it could even have an inductive pickup that just looped around a plug wire or something. Thanks!

Re hourmeter:

the version I have (Honda) has a tach function built in.

It has a lead that clips onto the plug wire to pick up the ignition pulses. Even comes with a lockwire arrangement to prevent tampering when fitted by bike shops etc. Unit is self powered so has no other cables to connect.

Odo or not, an hourmeter is still an excellent investment, a 'must have' in my opinion.

Take two bikes for example, one is on fire trails and may do a few hundred miles in a day and is due for oil/filter change.

The other is on tight trails and only does 30 miles, but the engine has done as much work as the above bike. The odo says that the guy riding the tight trails can do that loop another couple of times before he needs to change his oil. :cry: This is why it is better to guage engine servicing off running hours.

My 99 400 has 8000 miles on it...... I have the valves checked every 1200-1500 miles and change the oil every 4-500 miles.

I have never had to add oil to it between changes.

I think they publish these numbers to keep the service people employed. :cry:

I think they publish these numbers to keep the service people employed. :cry:

I AGREE !! :cry:

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now