how to fix 04 rmz250 problems

[bully_23]

hi everyone.
I have no idea about maintenance but i am willing to learn and I have read about the 04 rmz/kxfs valves problems now I am in the market for a new bike to start motocross on im 15 5'6 and 155-160 lbs and i am moving from a cheap chinese trail bike with a klx125 motor.now I have found a good deal on a rmz 250 that has just had a brand new topend done and titanium valves put in it also comes with a pro circuit oil filter. my question is would this eliminate the valve problems that come with stock valves and would I have no trouble with it if i did the regular maintenance of oil changing,oil filter and air filter cleaning would this make it run like a normal 4 strk like a yzf without any problems and when should a new top end be done. are there any other problem i should know about. Will this bike be long lasting or a money stealing timebomb if i should steer clear of this model what should i be getting that would be relatively cheap to maintain? please help and sorry for the long post

BuLlY

 

[biglou]

I don't think there's a very good "fix" for those bikes. Rich can explain better than I can, but I believe the crank bearing bosses are the weak links on these.

 

[Rich Rohrich]

Will this bike be long lasting or a money stealing timebomb if i should steer clear of this model what should i be getting that would be relatively cheap to maintain? please help and sorry for the long post

For a lot of racers these bikes make poor choices if you are the second owner. Your description of money stealing timebomb is a very good way to classify it.

If you want a relatively low maintenance second hand four-stroke find a clean well maintained YZF250, or CRF250.

 

[bully_23]

thanksfor the info on the rmz, I was looking at an 02 yzf today and I had a ride it was awsum but it took about half hour to get it started with the compression thing now I know i can fix that but how much would it cost to install that part. and with this done would this bike still not be good enough to hang with the newer 05-06 models would you suggest this bike or a later model but I wont have enough money to buy any higher than an 03 and most of the 03's around here are to expensive anyway. also can you outline the maintenance schedule that would have to be done and how often. Thanks a heap BuLlY

 

[Rich Rohrich]

Taken from Eric Gorr's Thumper Tuning tips :

The 250 YZF has been a fairly reliable engine but there are some things to pay close attention to. The 2001 had characteristic problems with crankshaft journals being undersized and fast wear to the cam sprocket. The balancer keyways and bearings tend to shear and wear which causes funky noises and vibration. Flywheel keys shear too which causes the engine to backfire and make it hard to start. If you’re a clutch fanner the plates will break and the particles will clog the sump screen causing a loss of oil pressure making the cams seize on the plain bearings. On the top end the titanium valves won’t give much notice before the heads shear off and corrosion of the valve seats from ethanol pump gas helps accelerate the wear. We use Kibblewhite valve train parts ($350) and the stainless parts last about 300 hours. Rule of thumb; when you have to install shim pads 3 sizes smaller than original, the titanium valves are junk. The 2001-02 models can benefit from Hot Cams ($275 set) because the exhaust cam includes a decompressor so you can kick it like a 2-stroke. The carbs are a source of problems, sometimes they blow off the manifold and the mixture screws vibrate out causing lean popping and low end bogging. You can Super-Glue the carb to the manifold. Regarding the mixture screw don’t waste your money on a stock one, buy a Zip Ty extended numbered screw. At least you can adjust it and monitor if its still in place.

The top end has a ton of potential because there are lots of accessories available for the YZ250F. Wiseco makes a lightweight gas-ported piston in the stock bore size and hi-compression that is great for the displacement racing classes. The 262cc 13.25:1 CR kit ($400) gives more power throughout the rev range. The Athena 290 kit gives way more low end but goes flat on top end without other mods like porting ($195) and Hot Cams ($275 set).

Additional Thumper Tuning Tips are available by Clicking Here

 

[marcusgunby]

rich you say the rmz has issues?? sounds like a few design problems with the older yzs?

 

[Rich Rohrich]

Marcus - There is no question that the original YZFs had issues. The upside is they are easy for the average rider to fix at home for a reasonable cost just by following a logical maintenance schedule. It's a fundamentally sound design which is more than I can say for the RMX/KXF debacle.

 

[bully_23]

ok thanks for the info but can you tell me the exact maintenanace i would have to do and how often thanks alot

 

[karterron]

Our fix, and we have never had a problem with valves is Boyeson pump, and 05 radiators. Change oil often, check valves when you do, and clean the filter also. Don't let people scare you away. Take care of the bike, follow good mainenance and you won't have any more trouble with it than you would with 04 Honda valves.

I don't doubt some people have problems and I bet most of them bring it on themselves by not doing routine work every RACE bike needs. Sure some are going to break even if you follow your scheduled maint, nothing is bulletproof.

Ride the bike like a 4 stroke, not a 2 stroke meaing stay off the rev limiter and HAVE FUN. We have never had one issue with ours and I know several others that haven't also, but all take care of their bikes.

 

[Rich Rohrich]

I don't doubt some people have problems and I bet most of them bring it on themselves by not doing routine work every RACE bike needs.

This certainly hasn't been our experience and we see a lot of RMZ/KXFs each month. We have seen enough deadly serious issues with these engines, even when they have been maintained by thoughtful professional mechanics to know there are basic design issues that can't be written off to simple lack of maintenance.

These issues only get worse for the second owner of the bikes.

All used four-strokes are a bit of a gamble, but in the case of the RMZ/KXF the odds are stacked in the parts guy's favor.

It's a shame really. Without these reliability issues this really is a great little bike.

 

[Rich Rohrich]

ok thanks for the info but can you tell me the exact maintenanace i would have to do and how often thanks alot

The service manual for the bike has a very good Service Interval guide.

 

[karterron]

This certainly hasn't been our experience and we see a lot of RMZ/KXFs each month. We have seen enough deadly serious issues with these engines, even when they have been maintained by thoughtful professional mechanics to know there are basic design issues that can't be written off to simple lack of maintenance.

These issues only get worse for the second owner of the bikes.

All used four-strokes are a bit of a gamble, but in the case of the RMZ/KXF the odds are stacked in the parts guy's favor.

It's a shame really. Without these reliability issues this really is a great little bike.

I've always been a believer in you get what you paid for. I have never in 25 years of riding had a lemon for a dirtbike. I have always taken care of my bikes, use good maintenance schedules, clean the bikes after riding them, and fixing every little problem that comes up before riding again. I was leary of going to 4 strokes after riding 2 strokes my entire life and I was almost scared off the 04 KXF/RMZ or the 04 CRF after hearing about all the problems with those bikes. I found that as long as you take care of them, know their weak points and either fix it or stay away from the what causes the problems (pretty much heat for all 3 of them, you won't have issues.

We haven't had any and both bikes were bought used. Again, I take care of my stuff and keep a rigid schedule. I wouldn't be afraid of buying another one either. Do your due diligence when buying used, find one that someone has taken care of and your chances are pretty good. I've been pleased and have no regrets at all.

 

[Chili]

karterron, How hard/frequent a use do your bikes see? How often have the valves and springs been replaced?

 

[karterron]

karterron, How hard/frequent a use do your bikes see? How often have the valves and springs been replaced?

The are used as often as the weather permits. Hard, I have taught my son not to bounce them off the rev limiter and to ride them like a 4 stroke. The 04 is on the second set of valves and the 05 is on the original. I keep careful records when I change the oil of where the valves are. When I start seeing movement I prepare for a top end when they get close to out of spec, no suprises.

I know others with similar experience. My belief has been the core problem is heat and that goes for the CRF or the KXF/RMZ. People who try and ride them like 2 strokes, bouncing off the rev limiter and don't do maint enough to track the movement are the ones with the most trouble. Sure, you will get the occasional breakdown, but that's true for any mechanical machine.

I was almost scared off these 4 strokes by the forum talk. I'm glad I wasn't now. Our experience has been good.