[Voncsn]

Just got myself a 2004 crf 250r, last bike I rode was at ama supercross Toronto in 2005 on a KTM 50. I ruptured my spleen 3 months after and havnt rode for 15 years. I was told I needed a piston when I bought it but the jug and piston were brand new just out of time. How much should I trust the bottom end I plan on only putting 5hrd or less and how do I put the money to make it indestructible. From a KTM guy cause I only raced 50cc thanks for the help

[JimDirt]

Welcome to the site !!

I guess the crank depends on the actual hours or abuse on the bike , for the most part you can get away with keeping the bottom end as long as a valve never hit the piston , or it does not have hours upon hours on it ..... I would be also checking the valves (the lash) as that is where the issues would show up first , if the piston was worn enough to need replacement , most likely the valves have been adjusted several times and are about zeroed out or close to it ........ Get yourself a Factory Honda Service Manual , it will give you all the spec you need to do anything to the bike ..... The actual Owners Manual will also give you piston , valve, crank specs , as well as service info on doing most everything , the Service Manual dives deeper into the components and also gives you electrical component tests and anything else you would encounter in working on the bike

As far as keeping it indestructible , the closest you will get is to keep the oil and air filter clean as often as possible , or as practical as you can within your budget allowances ..... do not over rev the engine where you are bouncing off the limiter , and don't get yourself in situations where you can overheat the engine , and all that that should get you some longevity

The wear items on the bike besides the obvious things like Tires and Chain and Sprockets are :

Clutch (check plates for wear or if slipping occurs , and check basket for grooving/notching)

Timing Chain (should be changed at each piston replacement)

Valves (check lash when doing service and once Intakes start moving it will be a matter of time before they are toast ... Stainless Intakes is the way to go , you will get much longer life from them)

Carb (since it is a 04 , it has a carb , so make sure you run Non Ethanol gas , and at least 89 octane or better 90+ preferred , this will prevent clogging of jets and general gumming up of the carb , when not riding for a few months or longer , such as during winter , drain the gas in the tank , you can use it in your car or lawn mower , but do not reuse it in the bike , gas goes bad , and these bikes do not like bad gas)

Grease.....( All bearing surfaces need grease , when you have downtime such as during winter or just before riding season starts , remove the wheels , triple clamps , swingarm/linkage and repack/grease everything with a quality waterproof grease ... Check bearings for notching , grab each item and turn/spin them , if it feels like there are detents/notches/clicking then they need replaced and are beyond greasing , you can get kits for the swingarm/linkage , or each wheel or steering head bearings and replace them all yourself)

Forks/Shock the forks should be serviced at the end of each riding season at least , depending on how much you ride , fresh oil , and possibly seals if they show signs of leaking , the shock you can go longer between service and your indication would be a bouncing/springy feel , much like a Pogo Stick , if the shock feels like there is no smoothness in it and just feels like a spring by itself , then it will need a Nitrogen recharge at minimum , and most likely a oil change , and possibly seal replacement , most casual riders don't do anything with the shock till it has issues , but the forks should be done at least once a season regardless

Other than keeping the bike clean , and your chain lubed , that should about cover it .... aside from air filter and oil changes frequently , the other items mentioned are seasonal , so once a year go over the bike and it will be ready for the next riding season usually trouble free ..

For example my bike I use Synthetic oil , I change the oil about every 10 hours , you would change it in half that time if using Petroleum oils , and the air air filter is cleaned/swapped every ride or 2 rides depending on conditions , if its dry/dusty , you need to do it every ride and keep it oiled correctly , if dirt gets past the filter , your valves are the first thing to suffer and they will go bad , along with the piston if all that dirt is grinding in the cylinder , so preventative maintenance is a must for longevity

That should get you on the right track ....