I'm back, but I have a 450 question

Having owned and thoroughly thrashed a 99 YZ400 and an 02 426 for 4 years with not so much as a single hiccup I bought a CRF450. It was a good bike but I was getting up in hours and after a few buddies of mine had their CRF's let loose and cost them each over $2000 to fix, I sold my CRF and bought a CR250. Now I realize I miss the thumper and am going to buy another one, this time a YZ450 as I personally think the YZ motor is a much stronger and more durable engine when compared to the CRF's. My wife's 04 CRF250 burns almost half it's engine oil in a 3 hour ride and it only has 27 hours on it, all of them by my wife. Should have got her a YZ250F...

Now my question is what maintenance intervals are you guys seeing on your YZ450's? How long till valves go out of spec, rings, etc. I know I will get a diversified group of answers and that's fine. I just don't see many posts here for YZ450 engine work compared to when you look at the CRF side of thumpertalk. That is all that's over there, guys blowing up their bikes, valves going out of spec, etc... I was thinking if I had noticed a large trend of engine work was required on the YZ450, I would just get a clean 426 and deal with the extra weight. I just haven't seen it. So if there are any weak spots, let's hear it...



Speaking from personel experience (I've owned a 400, 426, 2 450's) the Yamahas don't break and the valves don't seem to go out of spec nearly as fast. I think the other companies out smarted themselves by going to the seperate oil chambers. They end up with a lot less oil available to lube the valve train. Also with the oil in frame design of the Yamaha the frame actually acts as a passive cooling device. Contamination from the tranny/clutch has not proven to be an issue either. Also the five valve design affords Yamaha smaller lighter valves and springs that don't seem to get beat up as fast. And performance wise they have been awesome. My 03 was a doggone rocket! I'm hoping that my 05 isn't dissapointing compared to it from a power delivery standpoint. I'm sure that can be easily remedied though!

I've had my 450 almost two and a half years. Ridden hard for at least 4 motos a week which would be over an hour total each week so that's over 100 hours. I changed the piston and rings last month for the first time. They still looked good and were still in spec. The valves were also still in spec and still did not need to be reshimmed.

Pretty much bulletproof if you keep the oil changed.


I just picked up my 03. It has had the valves adjusted once from previous owner. They are in spec now. The top end had never come off as far as I know.

I plan on running it till '06 and then tearing it down. I bought this bike after considering a CRF250X it was sitting next too. The Honda stories were bugging me on maintenance and I'm a loyal Honda guy.

I'm glad I have my YZF. If I ever buy a new one, it will be an AhamaY too. :)


Sounds familar ...'99 YZ400F, '02 YZ426F, '03 YZ450F, and currently '05 YZ450F. The '03 YZ450F was great bike for me. I purchased it new in November of '02 and rode it at least six times a month and year round. I sold the bike just a month ago and everything was in spec. In case you are wondring why I went from the '03 to '05, it was mainly cause I could. The new bike bug bite me. As far as maintenance just the typical oil and filter stuff.

My girlfriend has an '03 YZ250F and it has been a great bike also. We lowered it two inches last month and it's like a new bike for her.

My 450 has been absolutely reliable. It's still waiting to have its first ever valve adjustment. The only thing that's ever happened to it is that it spat the decomp plug out, but hey... :)

Something that probably should get replaced before it's really worn out would be the cam chain. It's an easy job, and they're cheap insurance at $18. Letting them go is believed to cause premature wear of the crank sprocket.

My oil gets changed every 3 ride days (about 9-10 hours) unless I go racing, in which case I change before and after the race. I use a Scotts oil filter and clean it with every oil change.

Great feedback and it really echoes what I have been able to find and see for myself. I appreciate all the info. I have found a pretty clean 03 450 that I'm buying this week. I'm really looking forward to having a Yamaha again. I was a hardcore Honda guy until I bought the YZ400 and I guess I let the past draw me back in when I bought the CRF's. I can't see buying another one until Honda realizes that people don't want to tear the motors apart every 25 hours (wife's CRF250) or 75 hours (my old CRF450) for an engine overhaul.

What kind of hours are you seeing for the timing chain replacements? Probably coincide with a valve adjustment...

Not really. The chain is recommended for replacement every 1-2 years. Mine's that old and still doesn't need a valve adjust.

That's pretty impressive to go that long without having to adjust/replace valves.

I see you run a 4 oz flywheel weight. The one I'm getting has a 13 oz flywheel weight as the guy trail rode the bike. Have you tried any other weights other than the 4 oz'r? It seems 13 oz might be a bit much for MX...

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