How often should you rebuild even if you don't race

[HondaRaceReady]

What if you don't even ride that hard? I heard it's 40 hours. What would have to be rebuilt anyway? The piston should be fine, same with the cranks. Is it just the valves that need to be rebuilt?

[450rJam]

hard to guess, and I think the conditions you ride in have an effect on things also

im guessing mine had around 75-80 hours, its an 06 so it has ti intakes (good performance but not great longevity)

it needed valves replaced and while I had the head off I went ahead and did the piston/rings.............................

the stealership wanted 800 to replace piston/valves with stock

I dropped a little more but got venom cp 12.25 piston, port/polish, stainless valves/kw springs, and +1 exhaust
(good night this thing is insane quick)

if you keep the air filter clean, valves adjusted and oil fresh I think you should get 75 hrs out of it

[HondaRaceReady]

Will a 400ex ride for twice as long before a rebuild if it's maintained well, or are they bad too? 75-80 hours is as bad as a 2 stroke.

[chadbarger18]

a 400ex would go just about for ever with out a rebuild just maintain it real well oil filters and valves

[450rJam]

400ex will last forever (almost)

and I have got more than 80 hrs on a stock bore 250r

it really depends on how hard you are on it and how well you maintain it

100% dunes or racing will most likely need build sooner due to stress/conditions

[supersick300ex]

Have the compression checked and once it starts loosing then time to rebuild

[pro-rider46]

i would run it until she starts having symtoms because you can catch it before it really lets go and costs lots of money, and most likely if you catch it early enough the parts you need to replace are the ones that would be replaced anyway when you rebuild them.

[400exrider707]

Even though racers ride their machines hard, I find that most racers take much better care of their machines and are meticulous about maintenance. I would rather buy a race quad than one that has been trail ridden it's whole life. Just my findings...

No one can say how long it will last. Ride it til it blows. Rebuild it, repeat.

[Johnny B]

i have an 04 that gets ridden every day, and raced in cross country regularly, i have never had to rebuild or replace anything in the engine.

[GIXXER1KR]

Kepp an eye on the valve adjustment intervals.The faster they wear and need readjusting the sooner the valves are on there way out.Good oil and change often along with the air filter.Keep an eye on comp and youll be good for a good long time.

Originally posted by 450rJam
400ex will last forever (almost)

and I have got more than 80 hrs on a stock bore 250r

it really depends on how hard you are on it and how well you maintain it

100% dunes or racing will most likely need build sooner due to stress/conditions

i race my 250r an beat the **** out of it for at least 5 hours a day for the last 2 or 3 years an it has 195 comp an runs great i change the oil every 10 hours

yeah my brothers 2004 400ex is just starting to go now after 4 years of beating and my 2004 400ex was babied by the previous owner, when i bought it last year it had like 15 hours on it and it was a 2004! And mine is still running strong, I did a compression test and its still good. We beat the machines and ride them hard all the time, change the oil, adjust the valves, clean the air filter and they just keep running.