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How to properly maintain a four stroke?

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Hi there so after owning nothing but two smokers I bought my first four and I love it I could never go back! But can you guys give me some advise on maintaining this thing?


How often do you change oil is there a cost effective way? $31 to do so for both oils and a filter every ride just isn't in my budget...


what do I need to know about maintaining my valves?


how often do I need to Pack the pipes?

and is there anything else other then what I mentioned?



PS my bike appreciates all your input!


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Hey buddy,


Use to own that exact yr model crf. They are an awesome bike. As said above ensure oil level is @ 100% every time you take it out. The oil in these gets contaminated pretty quickly so ensure it is changed every 5hrs of use. Depending on how hard you ride it, I was pretty tough on mine around the tracks.


You also have gear oil you need to keep fresh. If you don't have one already I would seriously consider buying a manual for it. Very detailed info in there.


The intake valves on these from factory are junk. They eventually close up over time if not shimmed correctly and frequently, makes them a PITA to start. Will feel like it has crazy high compression when trying to kick over.


I had mine replaced with S/S items every top end and never had any issues after that and was always nice and easy to start.


As for the exhausts they are well.....rubbish. Bin them and get a full single system. Full exhaust, correct gearing for your riding style and jetting made a massive difference for me. Bike felt much crisper.


Hope this is of help to you. Enjoy it. I still miss mine to this day!

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I would highly recommend acquiring the service manual for periodic maintenance schedules. I can't talk to your specific bike, but my 2010 kx450f manual recommends changing the oil and filter every 6 races or 15 hours. This is assuming you are using conventional lubricants. The schedule in the manual is recommended to keep the bike running in good condition. Each bike's maintenance may vary depending on how it is ridden and treated. Just for reference, my manual suggests replacing the fork and shock oil every 6 races or 15 hours as well. Hell, that ain't going to happen. First of all I am not daddy Warbucks, and secondly I am not James Stewart out there working that fluid overtime. My riding does not require that high level of suspension consistency hour after hour. I have about 9 hours on a re-valved, rebuilt suspension, and I am still trying to fine tune it to my local track. I will change the suspension fluid when I feel its' performance starts to fade. That might happen at 15 hours, it might happen at 30 hours. I don't know. I am sure I will get a lot of haters for this post, but this is the reality of a lot of us weekend warrior riders. We are here to enjoy the sport without going bankrupt.  


My recommendation is keep the bike and enjoy it. Check the air filter for every ride, follow your oil changes and you should know when the valves need adjustment and suspension fluid needs changing. If you have the money and downtime, do it as often as you feel necessary. The exhaust packing will affect performance, but not much. It happens to slowly to realize it. It mostly will just be louder as the packing blows out over time. These bikes are more durable than most people give them credit for. After all if these bikes can take the abuse of professional riders (who ride then to the brink of destruction), they must be giggling like school girls when people like me jump on.

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First off, I highly suggest a service manual if you plan on keeping the bike (I don't see any reason why you shouldn't either, a lot of people ride on a budget, you just do what works best for you)


There is always a big debate on oil in these bikes.  Some guys only run synthetic (I personally run AMSOIL 10w-40 in both the engine and trans) and other people seem to really like rotella (I don't know which specific kind though)  They way I look at it, if your changing it frequently I don't think it makes much difference what oil you put in it (within reason obviously)  As for the frequency....I change mine every 4 hours. With the Honda heads know for eating valves, I considered it cheap insurance.  The manual will say the same as posted above, 6 races or 15 hours....but they also say to replace the piston every 15 or 16 hours so take that however you want.  I change the oil filter every other oil change.  I know Rockymountainatv.com used to have Honda GN4 oil for 22 dollars a gallon and you can pick up a small bulk pack of filters on ebay for a pretty decent price.  You def don't need to be spending 30 dollars per oil change.


As for valves, I was checking mine about every 10 hours.  I bought my bike used and got 70+ hours out of the head before it finally couldn't be shimmed anymore.  It was good up till the last 10-15 hours and would zero out the right intake valve within 5 hours.  I would run yours till they go, and then switch to SS, they seem to be a very popular option and seem to last a lot longer.  That is what im doing this winter.


As always, Its a good idea to go through and re-pack the bearings (swingarm, linkages, wheels, steering stem)  I don't have any experience with exhaust packing.  Never re-packed one before on all the bikes ive owned.  Am thinking about doing my race bike this year though, but its not on the top of my priority list.


Hope this helps!

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I have a 2006. My advice is go to Walmart buy the synthetic 10-30 5 quart jug 25$ (roughly) and use that oil for your crankcase. You do not have to have wet clutch compatible oil for that side.Buy the Honda 80-85 in the red bottle for your transmission. What kind of riding are you doing? If your doing woods or non track riding than the top end (depending on the condition) will last awhile. I ride woods and have over 100 hours on the motor with no valve movement. But I rebuilt my motor top to bottom with fastheads doing my head work. If you ride woods you can go 6 hours of motor running time no problem inbetween oil changes. I change transmission every 10 hours.

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Tons of great info already posted here.

-Get a service manual

-Hour meter is critical to stay on top of your schedule

-Walmart sells gallons of Rotella cheap (searching forums for oil recommendations will have you reading for decades and everybody has strong opinions/beliefs). Personally, what I've read and also seen from running it for years has me believing in the stuff (both on road/off-road bikes). Their semi-synthetic is all I need. Totally just an opinion though...

-Dig up the YouTube vid on checking the valve clearance on the '04-'08 CRF-250's if you don't already know how. It's so easy it's a joke and there is no excuse not to check it yourself very often.

-Shim whenever you need to so you're in spec, and if it gets to a point where it seems like you're shimming every time you check, have your valve seats cut and drop in some stainless valves. A lot depends on your riding style/level, but the regular shimming will become few and far between or practically non-existent with the steel.

Your best insurance against problems is frequent oil changes and air filter changes. You'll find your own schedule for these based on how hard you ride (oil), and the conditions where you're riding (air filter).

I made the switch from riding/racing nothing but 2-strokes for years and found myself hating the maintenance schedule of the 4-strokes. Not so much hating the work involved, just the worrying about horror stories I've read and the fear of them happening to me. Also- I'm not cheap by any means, but can't afford to throw endless gallons of GN4 at my bike. I run Rotella, use pre-oiled air filters I get off ebay for $11 and can throw away more often than I actually need, check/shim my own valves, and pretty much ride with no hassle/worries with the steel valves. Times changed and that's how I adapted.

Again... totally just an opinion and what works for me.

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Congrats on the bike! I've got an 06crf that was given to me by a buddy who didn't ride it much. Anyway, the PO didn't take much care of it and because of that, the valves went pretty fast (air filter was chocolate cake). Just listen to what has been said above. I like to do oil at 5-7 hours (I don't race yet, just trail riding for now) and filter every other change. I will religiously wash the air filter every other ride or every ride, depends how dusty it is during the ride. I do recommend the SS valve conversion when it's time to replace. Bought a brand new head with the conversion already in it from big bore thumpers. Other than that, get the jetting figured out to get rid of the big off idle. There's a sticky about in the forum

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