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Are the the new 4-strokes high maintenance?
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Posted by: Notto---------------------

I got out of dirtbikes about 5 years ago to focus on club level roadracing, but have recently gotten the bug to get a dirtbike again. I've decided to get rid of my race bike its just to expensive and dangerous for me to justify anymore.

Since I live in Colorado I would like to get a bike that is good in the woods but could do the occasional MX track if need be, maybe even motard it at some point. After riding my buddies YZ426 it seemed like the perfect bike, but now after doing some research it sounds like the new lightweight thumpers are a PITA with there constant need for valve adjustments. I'm aware of the fact that if you want high performance you often have to sacrifice bulletproof realiability, but I don't want to be doing a valve adjustment after each riding weekend.

Does the high valve maintenance mostly only apply to the Titanium valved newer models? Should I stick to the older steel valved YZF's and WR's or is it not as big of a deal as I'm making it out to be?

Posted by: nikki---------------------

My fiancé (Red) and I race MX and are on four strokes. He's been on them since 2001 and I have since 2002. In 2001 and 2002, we raced 30-40 times a year and play ride maybe 2-3 times a month. Red probably puts 2+ hours on his bikes at play rides as once you get him going, he'll turn laps for 45-60 minutes non-stop.

Anyways, here are a few quick facts on our experiences:

2001 YZ 426F (Red's) - Raced 40+ times and owned for 15 months, got a new top end and clutch (plates and baskets) after 12 months (but the stock stuff still looked like new - I think he was just bored and wanted to play mechanic), never needed a valve adjustment, fouled a plug or two, shattered a rear hub/sprocket. Other than the hub incident after 14 months of abuse, the bike was bulletproof.

2002 CRF 450 (Red's) - Raced 30+ times and owned for 15 months, looked at the valves/auto-decompression adjustment 3 months ago for the first time, valves were still perfect and auto-decompression was slightly out of adjustment, never fouled a plug. The bike has always started awesome and ran great with literally no maintenance (other than regular oil/filter/air filter changes).

2003 YZ 250F (Mine) - Raced 10+ times and owned 10 months, has hours on it from just about everyone I know, felt a little weak when WFO to me after 7 months and the oil sorta smelled gassy, so we put rings in it at 7 months. Everyone (dealers, people on web, etc.) thought it was way too soon for rings but I considered it cheap "insurance". No valve adjustments needed, no problems staring, clutch (as of 2 months ago) still looks brand new. It takes about 10-15 minutes to pull the valve cover and measure the valve clearances. And even if you did need to adjust the valves, you could pull the cams, replace the shims, reinstall the cams, and put it back together in a matter of 45 minutes or so. Compared to my last 2-stroke (2001 YZ 125 - owned 25 months, was a certified jetting NIGHTMARE, replaced 3-4 pistons, 6-8 rings, 2 outer baskets, 6-8 inner hubs, 6-8 sets of clutch plates, clutch cover, 2 sets of reeds, etc...) the four-strokes have been a breeze to maintain!!

Also - we have never needed to rejet any of our four-strokes, but since you're in Colorado... you might have to adjust for the high altitudes.

Posted by: the_tree---------------------

The 4 strokes take a little more maintenance than a 2 stroke, but have some benefits over a 2 stroke also (no premix or low hanging exhaust pipes).

4 stroke motors are awesome for the trails as the power is really broad.

I have an '01 KTM 520 MXC and it has been my all time favorite bike and I understand the newer 4 strokes are even better than it. Check out thumpertalk.com for some posts on particular 4 strokes.

My buddy has a '00 YZ 426 and it has been a solid bike.

Posted by: Jeffro426---------------------

Quote:

Originally posted by the_tree
The 4 strokes take a little more maintenance than a 2 stroke, but have some benefits over a 2 stroke also (no premix or low hanging exhaust pipes).

4 stroke motors are awesome for the trails as the power is really broad.

The new 4 strokes are NOWHERE near as much maintenance as 2 strokes. You can go WAY longer on a top end, dont have to worry about carbon buildup on power valves, no reeds to replace, no rediculusly big expansion chambers to have to punch dents out of, and best of all NO PREMIX!!! Change the oil, clean the air filter, and adjust the valves on a regular basis and you will have zero problems. Everyone has this preminition that just becuase you have to asjust the valves that it makes it more maintenance...try it, its so easy after you do it a couple times its like cleaning your airfilter.

Posted by: BadgerMan---------------------

I have ridden a 2001 YZ250F since December of 2000 and have yet to adjust the valve clearances. I check them regularly and they are still within spec. The bike has been trail ridden only, an average of three times per month.

Posted by: ecka---------------------

I have owned 2001 YZ250F and now have 2003 model.

Yes I do change the oil and filter on a regular basis (every 2 - 3 rides depending on time) but hey its not hard.

Apart from keeping the bike spotless I making sure all the exposed parts and cables are well lubed/rust protected etc, thats all I do. You do that on any bike don't you.

The valve clearance on my orginal 2001 model were adjusted once and the 2003 model (after 8 months of riding) are fine, they were checked last week in fact.

Maintance rating: Low
Fun rating: High

Posted by: Gary B.---------------------

I own one 2-stroke and it's for sale- I already have a full time job. Seriously, I trail ride and neither my KTM or my YZ has ever been apart farther than a yearly (maybe) valve adjustment. I doubt I'll ever own another 2-stroke. The older 4-stroke were buggers to start, but the new ones are a breeze (no matter what those So-Cal magazine wussies say). :thumb:

Posted by: Notto---------------------

Thanks for all the replies guys. I'm not scared of doing routine maitenance, and it sounds like the valve adjustments on these bikes are realitively easy. After riding 2 strokes and streetbikes, I was getting tired of spending my free time tearing down engines. I'm going to be putting up my R6 for sale next week and hopefully if it sells I will be buying myself a new bike. Now I just have to decide between a YZF, a WR or a CRF. :thumb:

Posted by: JasonJ---------------------

You mean your supposed to maintain a 4 stoke?

. I neglect mine fairley regularly, Its often protected only by the cacoon of dirt that I never was off of it unless I ride it in the rain. I do try to change the oil and filter every 2nd or 3rd ride wich is about every 5-8 hours. I spray the lever pivots and kick starter with WD 40 and lube the chain every ride before and sometimes after if it gets wet. I have a 99 WR 400 and the valves have not needed adjustment in the 3 years Ive had the bike, but they are steel. I can kick the bike from the saddle and she starts usally first kick when warm, maybe 3rd kick when its been sittin a few weeks after priming, not a problem. This is the funest most powerfull bike I have owned and it has taken the least amount of maint and has never broken on me on the trail (did run out of gas once :O ). Oh and the WR rips the trails up and dose not wear you out since it rides best when you keep your feet on the pegs.

Posted by: cujet---------------------

I have to give my point of view. The modern 4 strokes are reliable, however they are not inexpensive to overhaul. One could spend $1500 on a complete top end. Some CRF's have had valve recession problems and that may be the source of the frequent valve adjustment discussions. Some of the KTM 4 strokes (which I love) have had valve train issues with total destruction of the head resulting from certain failures. Eric Gorr has a good handle on this problem. Some of the Yamaha and Honda bikes have had crankshaft wear and strength problems.

I suspect that the engine life is inversely proportional to RPM. Riders that keep the engines on the rev limiter have shorter engine lives.

I believe that bikes such as the CR500/KTM300-380 and similar are less expensive to operate in the long run due to long engine life and low cost of overhaul.

Chris

Posted by: kx200---------------------

You better get the WR so if you do motard it later you will have the wide ratio transmission remember the YZ450 is only a 4 speed and the WR250 4th gear is the same as the YZ250’s 5th (1.042 to 1) the CR is also a close ratio 5 speed
Gas Gas and KTM are 6 speeds EFI on the gas gas might be nice in the higher elevations

Posted by: MWEISSEN---------------------

I've had an XR250, a WR400 and YZ250F and though I'd stick with four strokes forever until I got a KTM 250. Also, the YZF ate its head (part my fault, part wear). Talk about $$$ and PITA! I now have CR250 to replace the YZF.

Posted by: Hick---------------------

Quote:

Originally posted by Notto
I'm going to be putting up my R6 for sale next week and hopefully if it sells I will be buying myself a new bike. Now I just have to decide between a YZF, a WR or a CRF. :thumb:

Didja ever have to adjust the valves on the R6? From my understanding the valve train on the YZ/WRs is nearly identical, the main diff being there's only one set...

The YZF and CRF, or any MX bike, have close-ratio gear boxes. I've ridden Rampart on my YZ and battled rear brake fade, the super-low first gear of the WR is much more suited. Having said that I wouldn't want that gearbox on a motocross track...

I currently ride an '03 CRF and, while I've heard of some problems with the intake valves wearing out, mine are holding up with no adjustments needed as of yet at about 50 hours or so. Depending on how often you ride you could go an entire season and only check them once, so I wouldn't say that is an issue. Also, I was aware of the (relatively rare) valve problems with the CRF but I don't think it is a deal killer. The vast majority of bikes have no problems, and if mine does I think it is a problem that can be dealt with...

What I don't get is why road bikes like the R6 seem to be 1,000% more reliable than their dirt counterparts. The WR450 can upchuck a woodruff key on occasion, a small number of CRFs eat valves, but do you ever hear CBR and R6 owners bitching about stuff like this?

Just curious.

Posted by: cujet---------------------

Hick, you have a good point. I am sure that most will say that the street bikes spend more time at low RPM. However I do not buy that! Some street bikes see nothing but race duty with RPM's far above the dirt bike level. And they function with excellent reliability.

I think the 4 stroke high performance dirt bike is still a fairly new thing and it will take time and complaints to get the manufacturers to design in more reliability.

I wish Honda would use a VTEC system in the CRF!

Chris

Posted by: Notto---------------------

Quote:

Originally posted by Hick

Didja ever have to adjust the valves on the R6? From my understanding the valve train on the YZ/WRs is nearly identical, the main diff being there's only one set...

Yes and it wasn't bad at all, I was just a little concerned after reading some of the posts of people having to adjust the valves every other ride.

Quote:

What I don't get is why road bikes like the R6 seem to be 1,000% more reliable than their dirt counterparts. The WR450 can upchuck a woodruff key on occasion, a small number of CRFs eat valves, but do you ever hear CBR and R6 owners bitching about stuff like this?
Just curious.

No but road bikes have their own problems, R6's are notorious for eating trannies, and CBR's have LOTS of problems with CCT's going. I've been realitively lucky with my R6, its been pretty much bullet proof even after racing it for a season.

Thanks for your input its much appreciated :thumb:

Posted by: motometal---------------------

valves shouldn't need adjustment every 2 or 3 rides.  if they do, something must be wearing significantly (valve seats or faces, etc.)

for every story of a YZ400F that went years without a top end, i'm sure we could muster up an equivalent case of a 250 two stroke that went years without a top end.  I know a guy that rode an RMX250 on a regular basis for four seasons on a top end, and it still had good compression.  The piston was a bit worn, but not bad.  This is the same guy that changed trans oil once a year and the air filter got attention 1-2 times per year.  Sure, this is an extreme case, but honestly the high maintenance of two strokes is WAY exaggerated.

Posted by: kx200---------------------

I have an old KDX 200 that is just like a 4 stroke, in that the only thing that goes wrong with it is its power valves. They shear the teeth off after 2 or 3 seasons I'm finally getting the cylinder re-plated after 14 years

Posted by: Gary B.---------------------

I'm a big believer in maintenance and generally paying attention to things. I think 95% of all motors built these days, weather motorcycle or otherwise, will last a good long time unless neglected or abused (over-revved, overheated, fluids never changed). :flame:

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Are the the new 4-strokes high maintenance?

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