dirtbikenut

My son and I have been riding CRF450's since 2002 and he's the type of rider that puts LOTS of hours on each bike he rides; as many as 120hrs on a single bike!
Through this and being that I am his mechanic I have a few tips for maintaining these beasts.

1. Piston and rings:
- you should ring them at about 40hrs. You can let them go longer if you use GOOD oil and always use a clean air filter (we have gone up to 80 hrs on a single piston). If you go that long it may wear the piston so much as to warrant replacing the piston and rings and the cylinder may. This is due to the rings wearing and the piston wanting to **** sideways in the cylinder.
2. Valves:
- We have not had a valve problem with these bikes, though at 80 hrs you will want to keep an eye on them and replace them anytime after that. We have gone over 100hrs w/o replacing them. I'm not saying that you should also, but at 100hrs you SHOULD replace the valves, guides, seals, springs, retainers,keepers and cam chain. You may just find it more cost effective to replace the entire cylinder head; the cost for a complete head is about $250 from Service Honda .com .

3. Brakes:
- they like to go through rear brakes. We go through a set every 6wks or so, depending if we race or not. Rockymountainatv .com has good prices on brakes. Also, we have gone through rear rotors at about 40hrs. The rear brake has a habit of tearing it's master cylinder seals. If you can push the rear brake until it hits the foot peg mount you need to rebuild it. This can happen anywhere from 15 to 40 hrs. Also, the rear brake hose can spawn a small leak where it bends just exiting the master cylinder. This sympton wil feel the same as a torn seal in the master cylinder. You'll need to troubleshoot this one with patience!

More later!

JThompson

I never saw this thread but those are some great CRF450 Maintenance Tips

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tigmaster

A Ready oil filter also does wonders. Jim and I both have the 450r motor, mine the bike and his the quad. We change our oil every ride but Jim has a Ready filter and at the moment I am running the paper filter. Jim's oil is noticeably clearer throughout the day. I plan on getting one, just can't swing $50 at the moment. I would strongly recommend it. I run GN4 in the transmission side and Maxima SynBlend in the engine. No troubles, just keep up on oil changes and keep the filter clean. I have put maybe 30-40 hours on the bike since I got it and shimmed the valves plus a new piston and rings. Tolerances have not moved one bit and compression is exactly the same. Very happy with my bike. I sure put a huge amount of load on the engine at the dunes and it was constantly in a state of overheating but the oil was still perfect after the first days change and clutch still grippy as ever.

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APE_JEFF

What in the world. i just did my top end after 5 years on my 03 crf 450. Took my old parts into honda, they miked them told me that the piston had .002 ware and the jug needed to be deglazed. mind you i ride this thing almost ever weekend. run it at the sand drags beat on it hard. even the cam was still perfect. i use honda gn4 oil only. honda told me to put it back together with the same parts. i didnt but i think a top end every 2 months is a bit much.

wr250f95

not if you race it, I ride mine as frequently as you do yours, granted I Ride a yami wr250f, but I keep the air filter clean, oil changed, and oil filter clean, check the valves once a year, and call it.

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"LIFE'S JOURNEY IS NOT TO ARRIVE AT THE GRAVE SAFELY IN A WELL PRESERVED BODY, BUT RATHER TO SKID IN SIDEWAYS, TOTALLY WORN OUT, SHOUTING'...HOLY S**T... WHAT A RIDE!"

this, is why I ride.

gscx

ok, so even if you do race it you can go as long as anyone who doesnt race. "racing hours" are the same as "practice hours". If the same rider rides it EVERY weekend at a race and thats it, he only gets 2 four lap motos, or six,or seven lap motos. and then a around 2 lap practice. And sometimes 2 15minutes practices the saturday before a race. Ok, so that like what? 45mins a weekend? So dont ask if a bike has been raced, becasue that doesnt mean anything

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wr250f95

actually it does, a yzf that was raced is going to have had more stress put on the motor than a yzf that was ridden by a 13 year old kid in his back yard.
also, some of the guys that i Know that race, run the same bike till its valves are fixing to go, then sell it, probably where the used 4strokes are ticking time bombs thing came from.

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"LIFE'S JOURNEY IS NOT TO ARRIVE AT THE GRAVE SAFELY IN A WELL PRESERVED BODY, BUT RATHER TO SKID IN SIDEWAYS, TOTALLY WORN OUT, SHOUTING'...HOLY S**T... WHAT A RIDE!"

this, is why I ride.

gscx

ok, so the 13 year old racing th ebike is different than the 13 year old practicing on the bike?

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wr250f95

most likely, if he races hes going to have most likely had it pinned for a decent amount of time, if hes just practicing theres a good chance he could have just been piddle farting around.
that and bikes that have been raced have more than likely been through some rad nasty crashes.

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"LIFE'S JOURNEY IS NOT TO ARRIVE AT THE GRAVE SAFELY IN A WELL PRESERVED BODY, BUT RATHER TO SKID IN SIDEWAYS, TOTALLY WORN OUT, SHOUTING'...HOLY S**T... WHAT A RIDE!"

this, is why I ride.

gscx

ok, so if you go slow during practice you go slow in the race, if your a slow rider your a slow rider, weither you race or not

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