Ok, so let me put it this way...

Since my "shocking revelation" post was locked, I better put my question another way.

I have some concerns about High-performance motocross four strokes. I read an article that said that they are nothing but constant maintence and work. It says that they need to be meticulously maintained. That worries me, because I am seriously looking into buying a 2001 YZ426F. And, if the previous owner neglected the bike to the point that something was seriously wrong, and escaped my attention. My worry lies in the fact that I am pretty much completely 4-STROKE ILLITERATE. You hand me a valve and i am dumbfounded :crazy: I have ALWAYS been a 2-smoker and thats all I know (i suck with cars too). I am compeletly willing to learn, but when buying a used four-stroke, i'm worried that I may get screwed because of my ignorance. I know that there are risks in buying used bikes whether they're 2 strokes or 4 strokes.

The maintence that I am used to is:

Cleaning and re-oiling the air filter after every ride

changing the oil after ever 3-5 rides

New top end every season or every other season

and

the other usuals (chain adjustment, cleaning, ect.)

The maintence that I've heard for four strokes (in addition to the above) is:

New top end every 40 hours

Checking the valve clearance every 20-40 hours

changing the oil and filter every 10 hours

not to mention all the other internal parts that I'm to ignorant to know what to do with.

all that and more just to have it blow up on you anyways costing 2600 bux. in parts.

It sounds OUTRAGEOUS, rediculous, and everything else, but hell i don't know if its true or not. HELPFUL POSTS are appreciated but PLEASE DON'T FLAME ME AGAIN...i'm still healing from the burns from my last post....they hurt...

If you're used to changing the oil every 3-5 rides, and keep up regular maintenance (i.e. air filters, chain adjustment, valve adjustment) you'll be fine. The number one thing is oil, if you're using dirty oil, you're sacrificing engine life. The new top-end every 40 hours seems like a lot. Depending on how hard you ride you may be able to get a couple season without a rebuild, I have 3 years on my 03 YZ250F and it's still running great. All that will be new to you is the valve adjustment. It only takes about a half hour and once you know what to do, it only gets easier.

The maintence that I am used to is:

Cleaning and re-oiling the air filter after every ride

changing the oil after ever 3-5 rides

New top end every season or every other season

and

the other usuals (chain adjustment, cleaning, ect.)

The maintence that I've heard for four strokes (in addition to the above) is:

New top end every 40 hours

Checking the valve clearance every 20-40 hours

changing the oil and filter every 10 hours

not to mention all the other internal parts that I'm to ignorant to know what to do with.

all that and more just to have it blow up on you anyways costing 2600 bux. in parts.

It sounds OUTRAGEOUS, rediculous, and everything else, but hell i don't know if its true or not. HELPFUL POSTS are appreciated but PLEASE DON'T FLAME ME AGAIN...i'm still healing from the burns from my last post....they hurt...

I don't know what you read but in my experience 4 strokes are way more reliable than two strokes. Ask anyone on here and they will tell you that the yz 400 and 426 motors are bullet proof. and from what I've read they are even more durable than the 450! in fact just today when I was riding I saw a guy on a pinger rippin it up. not 5 minutes later i saw him pushing his bike. I asked him what happened and he said the motor locked up. another fried piston! :ride: I will tell you this I will NEVER own another two stroke! I have a yz 400 1998 and I just ride it. load it into my truck, ripe through the desert in 100 degree heat, load it back in my truck and get ready for the next ride. This is the first bike I've owned that I was wondering if it would get me back to my truck! :crazy:

BTW you do not have to replace the piston every 40 hours probably like 400 hours

sorry you had a harsh intro to TT Most everybody on here is really helpful :ride:

You're a brave one. I liked the golf comment the best.

The only difference between how I maintain 2 & 4 strokes is frequency of oil changes (every 200-300 miles) and checking the valves (after break in, and once a year after that). If you buy something other than a Yamaha, valve checks are more frequent. Get an owners manual and it describes in detail how to do everything. If you're getting an older bike, its going to need a rebuild at some point. So maybe an '04 bike is a better deal than an '01 if you factor in the cost of a rebuild.

That said, I wouldn't buy a used 4 stroke unless: 1) I knew the previous owner, or 2) the previous owner was an anal retentive mechanic and had detailed maintenance records, or 3) it was a Honda XR.

Jerry

So i just need a feeler gauge and i'm set? Take off the cylinder head, and check in clearance? huh. Even i can do that. and i suck. How often do you change your oil?

Hi,

No you DO NOT need to take cylinder head off to measure valve clearance :crazy: You just take a cover of so you can see cams and you measure it from there.

I change piston and conrod every 150hrs and I don't take my engine in parts other times.

Timo Mc

The maintenance on the 4 strokes isn't really that bad but honestly, if it worries you you really should not be buying a 2001 bike...

Sooner or later these are all going to need some complex maintenance and the 2001 bike will be a lot sooner than the newer ones.

Not to say there's anything wrong with it, but as you said, you don't know how it was run or maintained. When these motors tank, it's a very expensive proposition to rebuild them as you already know.

When I looked in to getting a 4 stroke I heard the same stuff you did, and I chose to bite the bullet and buy new so I knew how it was taken care of and run from day 1.

IMO, I don't think 4-strokes are more maintenance intensive then 2-strokes; they just require more TIME when you do the maintenance because there are more parts you have to deal with. Taking a wrench to a 4-stroke isn't anymore scarier then the first time you took a wrench to a 2-stroke.

Valves:

"Checking" your valve clearances is easy! You only have to remove your seat, tank, and valve cover. You need to know how to set your bike to TDC and then you check your clearances with a feeler gauge.

"Adjusting" your valves is a little bit more difficult the first time you do it because you do have to remove more parts and you have to be diligent and careful when you are doing this. If you have done the top-end on a 2-stroke, you do have the skills to adjust your valves. The important stuff is making sure your Timing is correct, you don't mix up your valve shims, and don't over-torque parts. Follow the shop manual and it's a piece of cake. I've only had to "Adjust" my valve once on a 03 wr450. I've "checked" them about 3-4 times.

Filter and oil: I change my oil every 2-3 rides because the bikes take less then a quart, and I'd rather be safe then sorry. It cost less to put oil in the bike then it does to fill the tank with gas. Why not change it??? Clean the air filter the same as a 2-stroke.

Piston: 40 hours is excessive. I race my wr450 and I change mine every winter. About 60-100 hours, and that's pretty excessive if you religious about changing your oil. But I like the piece of mind.

Buying used: This is just a big gamble because you don't know how good the other guy was with his maintenance. Most people are pretty lazy. :crazy: If it was me, and I was buying used, I would change the oil/filter, check the vavles and replace the piston before I rode it just to be safe.

I ride these bikes strictly on MX tracks - here is what I think. I believe that there is more maintenance with a 4 stroke in the long term. In the short term no not anymore at all....A new YZF450 motor will not need to be opened up for a year or more unless you are very meticulous. Oil changes are the key here every 5-6hrs maximum (my opinion and routine). I have had 2.5 years on a stock YZF motor before ever opening up (riding/racing every weekend sometimes twice or more a week)...and everything was still in spec.... :ride: You have valid concern looking at a 2001 bike no doubt...especially one that you have no idea how it has been maintained. Valves are durable if kept in spec and cam chains need to be changed. Top ends last a lot longer than 2 smokes...again I ask what your budget is for this purchase?

I would buy the newest bike I could afford but I will say that any 2001-2005 YZF is bulletproof compared to any other brand 4stroke period.

2smokes are fun but predictable and I used to go through topends every 40-50hrs of riding/racing minimum..... I would buy a 1-3year old 450 from someone I know that is anal about the upkeep with their bikes...like I am......if I could not afford a 6500.00 new one....they are to me more fun to ride and the technology just keeps getting better and better....

Also make sure if you buy the 2001....make sure you get the starting drill down or buy one with the autodecompression installed....I know several people like you (newby to 4strokes)that just could not deal with the starting routine and now have "bad attitudes" towards these bikes...

my 2 cents...... :crazy:

is this out of the CFR manual? :ride:

The maintence that I've heard for four strokes (in addition to the above) is:

New top end every 40 hours

Checking the valve clearance every 20-40 hours

changing the oil and filter every 10 hours

not to mention all the other internal parts that I'm to ignorant to know what to do with. :lol::cheers::cheers:

My YZ450 is 3 years old. I've checked the valves which is very easy. Other than oil changes and clean air filters......that's been my engine maintenance schedule.

That isn't too tough is it?

there was a post in that thread that is a glaring example of why I will not buy a used MX bike....

"change the oil every 10h to 20h" or something similar...

wow.

My YZ450 is 3 years old. I've checked the valves which is very easy. Other than oil changes and clean air filters......that's been my engine maintenance schedule.

That isn't too tough is it?

And mine has been a mirror of that. I stress checked the valves, no adjustments yet.
The maintence that I am used to is:

Cleaning and re-oiling the air filter after every ride

No difference

changing the oil after ever 3-5 rides

Should be every 2-3 rides, to a maximum of 8-10 hours. The YZF shares engine oil with its transmission

New top end every season or every other season

Mine is currently 3 years old without so much as a valve adjustment. I did replace the timing chain last year

and

the other usuals (chain adjustment, cleaning, ect.)

same thing

The maintence that I've heard for four strokes (in addition to the above) is:

New top end every 40 hours

Not on a YZF. Mine has something like 180-200 on it right now

Checking the valve clearance every 20-40 hours

20 hours is roughly 7-10 ride days, counting the hours as time the engine was actually running. That's a good place to start, but as I say, it should be a very long time until you need to adjust, at least if you measure from the time the valves were new. Once an adjustment has become necessary, check them twice as often.

changing the oil and filter every 10 hours

[2-3 rides, to a 10 maximum, IF you use a good quality oil that retains its viscosity well in a gearbox

not to mention all the other internal parts that I'm to ignorant to know what to do with.

Cam chain every 1-2 years (a one hour, $30 job)

all that and more just to have it blow up on you anyways costing 2600 bux. in parts.

There are 3 "common" reasons that YZF's "blow up", realizing that YZF's blowing up is not at all common:

1> Neglect, and/or stupidity (the first is inclusive of the second). Drain plugs falling out, failure to change oil, filter, or check levels, failure to maintain coolant, etc. Four strokes are somewhat more negligence-intolerant than some of the tougher two strokes are.

2> Big end failures. Happens sometimes, but usually, it's just a siezure, and not a very expensive repair.

3> Broken valves. This goes back to negligence, 95% of the time. When any valve has been adjusted to a shim size .20mm or more smaller than the original, you run the risk of breaking a valve by continuing to use it. At that point, there is enough wear on the valve face to cause it to scoot to the side as it closes, if the wear is not completely even, which in turn flexes the valve stem up to 80 times a second, and can lead to the stem snapping off. Very messy, but usually your fault.

Another avoidable cause of this is an old cam chain, and the wear it causes to the crank sprocket.

Another is failing to replace valve springs when the valves finally do get replaced.

Other brands are frankly not as durable as the big YZF, at least, not without spending some money up front to modify them. If that is your main concern about owning one, stick with a Yamaha.

So then I'm not risking anything more by buying a used four stroke than buying a used 2 stroke. If mainenence wasn't done on either of them, there will be problems. thanks for you help everyone

I didn't, and wouldn't, say that, exactly. There are no moving parts (in fact, there are no parts) in a two-stroke head. A YZF head has roughly $875 worth of moving stuff in it, not counting the head itself, which can be worn and damaged if treated wrong. Neglecting the bike puts all that at risk.

But properly maintained, the big YZF's are only slightly less reliable than sundials.

When going to look at a used 4 stroke I recomend that you have the guy take out the oil filter. I think that if someone is too lazy to change the oil and filter before putting it up for sale then they are too lazy to do the other maintenance. I would also check the airbox. If it is completely spotless, that is a sign that he really cares about his bike. Also, if he has a bunch of air filters (real air filters, not ready filters) I see that as a sign that he cleans his air filter so much that he buys spares so that he doesnt have to clean his air filter every time he wants a fresh one.

The guy I bought my 450 from included 5 extra air filters, 3 extra oil filters, and the airbox was spotless to the point that I would be willing to eat off of it. I have not had any engine problems with this bike. He checked the valves and they were still perfect. (in spec and none of them had shims). So, not only were they in spec, but they were the stock valves and the bike is 3 years old. My bike starts first or second kick every time when cold, and it always starts first kick when hot. I couldnt be happier. I guess the point I am trying to make is that you should watch for tell tale signs that the guy takes care of his bike when you are looking at buying it.

When going to look at a used 4 stroke I recomend that you have the guy take out the oil filter. I think that if someone is too lazy to change the oil and filter before putting it up for sale then they are too lazy to do the other maintenance. I would also check the airbox. If it is completely spotless, that is a sign that he really cares about his bike. Also, if he has a bunch of air filters (real air filters, not ready filters) I see that as a sign that he cleans his air filter so much that he buys spares so that he doesnt have to clean his air filter every time he wants a fresh one.

The guy I bought my 450 from included 5 extra air filters, 3 extra oil filters, and the airbox was spotless to the point that I would be willing to eat off of it. I have not had any engine problems with this bike. He checked the valves and they were still perfect. (in spec and none of them had shims). So, not only were they in spec, but they were the stock valves and the bike is 3 years old. My bike starts first or second kick every time when cold, and it always starts first kick when hot. I couldnt be happier. I guess the point I am trying to make is that you should watch for tell tale signs that the guy takes care of his bike when you are looking at buying it.

Your bike had no shims? :crazy:

When going to look at a used 4 stroke I recomend ....
I guess you won't be buying one from me. I find that a week between rides is enough time that I don't need an extra air filter. The inside of my air box isn't spotless either, nor will it be, unless I have the cash to replace the bike before it goes up for sale. The most I bother to do with it is wipe it out before and after the filter is removed for cleaning. Worrying about having the air box "spotless" tells me that somebody is either dangerously obsessive, or doesn't have enough to do. Besides, if I see a spotless air box, I want to see the wash cover he used to keep the water and crap out while he did that.

And I'm not going to pull the oil filter out for anyone, either (or dismantling it in any other way, for that matter). I don't have any on hand because I use a Scotts, and I only need one. If we make a deal on the bike, I will walk you through a complete oil change if you want to learn how it's done, but it won't need one.

And I'm sure you meant to say that none of the valves had ever needed to be adjusted; they all have shims.

I don't know why you some of you guys are talking bad about 426's especially the 2000's. In my opinion the 426's are the most reliable of all. In fact I will bet that a fairly well maintained 426(Especially 00') will outlast any 450. In fact if you don't race competively the 426's are better all around than the 450's.

Don't be afraid to buy a used bike. If your not sure about the maintenence schedule or don't know the guy you bought it from I would suggest going over the motor or have a buddy or a shop look it over so you don't have any problems in the future because 4 strokes can sometimes (hardly ever) can make you go "OOPS" in a big way.

I guess you won't be buying one from me. I find that a week between rides is enough time that I don't need an extra air filter. The inside of my air box isn't spotless either, nor will it be, unless I have the cash to replace the bike before it goes up for sale. The most I bother to do with it is wipe it out before and after the filter is removed for cleaning. Worrying about having the air box "spotless" tells me that somebody is either dangerously obsessive, or doesn't have enough to do. Besides, if I see a spotless air box, I want to see the wash cover he used to keep the water and crap out while he did that.

And I'm not going to pull the oil filter out for anyone, either (or dismantling it in any other way, for that matter). I don't have any on hand because I use a Scotts, and I only need one. If we make a deal on the bike, I will walk you through a complete oil change if you want to learn how it's done, but it won't need one.

And I'm sure you meant to say that none of the valves had ever needed to be adjusted; they all have shims.

what I had meant to say is that he did not have to adjust them at all. The guy I bought my bike from was anal. He did race it, but it was in the 250D and the vet class(or something like that). I know for a fact that he raced in two classes. He claims that if the track was dusty that he would change his air filter between motos. He would change the oil and filter every 6 hours and because of his maintenance (which some call obssesive) my bike has not needed anything except a chain and wheel bearings on the right side of the back wheel. I dont think there is such a thing as changing the oil too often or cleaning the air filter too often.

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