2007 RMZ-250 Valves, replace them or not?!

Hej guys! I have an RMZ-250(2007), 80-90 hours in it(approximately) but it is a hobby bike. Last season was my first in MX. This year im a bit better. Im asking for some help! Its for sure that I have to adjust the valve clearance but Im wonder that I need to replace them at all? And what about the piston? Should it be replaced or what determines the replacement of the piston or the valves? thanks in advance

adam

If it's 80 to 90 hrs of medium riding I would not replace anything, just check your clearance, actually it was more inportant to do that after the first 20 hrs but just do that for now.

Don"t worry about the piston/rings for another full season.

If your pushing the bike to it's limits in racing, then you should replace the valve and piston and rings now.

Thanks for helping me

We just opened up a YZ250f with a Athena big bore kit in it. 290F now, one piston ring as opposed to the stock 250F which has 2 rings. The maker stated replace piston and ring after 15 hrs, the bike had 120 hrs and 1/3rd of those were racing hrs. It was due but not bad at all.

If you're a mellow rider, do not hesitate to get up to 120 hrs before opening it.

290F thats amazing man

and you say after 120hrs its still quite okey?

Anyway.. Im gonna have my valves adjusted and hope everything is in good condition. As far as I remember I changed oil after 7-8-9hrs and used Motul 300V Factory Line. What annoys me is that there is smut in the end of the muffler. But for 2 months there has been quite much smut there. Probably its because I should have already checked the valve clearance and I havent really been able to use a full gas to completely burn gasoline. Perhaps I should change the jet in the carburator. What do you think bout it?

Sounds like you're running too rich for your riding and that is dealt with by jetting. I am not familiar with Suzukis jet size but you would need to go down on the jet size. Check with guys that have RMZ at your local track or ask the dealer when you bring it in for the valve check.

If you have smut though, that is from burnt oil and that is customary on 2 strokes that run too rich or their oil mix is screwed up. In the case of a 4 stroke there should be absolutely NO smut at the exhaust at all, even when running rich. Sometimes when the piston and rings start to have a little play you end up pumping a little engine oil on top of the piston and that may be be what is being burnt and creating the smut at the other end???

Talk to your dealer who will have lots of experience on your make of bike and will be able to recommend opening the engine or not on the basis of the smut you have there! That is not normal.

What do you mean on Im running it too rich? Do you mean the amount of fuel that the combustion chamber gets? Sorry, Im not English at all.... On the other hand my dealer sucks. They are incredibly lazy, and tend to cheat on people. Im gonna bring my bike to one of my friends who worked for yamaha for a couple of years, and also got lots of experience in go-carts and in an EVO6.

The most incredible thing about this smut that Ive been having this problem since I bought the bike. And it was a new bike. At the beginning there was just a little amount of smut but for 2 months there has been a massive amount of smut. I dont understand why, at all..

Too rich is too much fuel for the air, too lean would be not enough fuel for the air amount, it is a ratio for the combustion but nevermingd that, if you have smut coming out at the back, your problem is not jetting on a 4 strokes, it's engine oil that is making it's way to the top of the piston and burns. That happens when the piston and rings get a little play, the crankcase pressure manages to push some little oil up pass the rings on the exhaust stroke and/or intake stroke (while there is no combustion in the cylinder for those two strokes (up and down) before the combustion and expansion strokes and that oil is what you see coming out at the back. You unfortunately have a problem and when he opens the top end, it should be evident on the valves and on the top of the piston that you are burning some oil. YOu would not notice it on the oil level of your bike since you probably change the oil frequently. Get it checked by your buddy cause you don't want the piston to start banging in there, it can get real costly.

And what if there is smut on the surface of the piston and on the valves.. What could've caused it? Could it be cuz of the oil seal rings on the valves( im not sure wheither I used the proper word for oil seal ring) And what could be the consequnces? I heard that in one of my friends' RMZ the piston just broke during riding... It was I think 05RMZ but I dont know the reason for it. I do not really want to experience such a case..

What I dont understand why Ive been having this for the very beginning. There has been smut at the end of the muffler since I brought it home from the dealer.

Usually bikes have annoying banging noise when u release the throttle especially at a high rpm if the valves are worn, mine has never had such a sound. You know what I mean? I tried to be as clear as I could.

Well, it really sounds like you have a problem. smut coming out of the pipe on a 4 strokes is not a good sign! I've described it to you already, your piston and rigs are getting loose and while moving up and down in the cylinder oil manages to climb up pass the "oil ring" as you call it and gets on top of the piston, doesn't burn completely and comes out at the other end of the pipe.

NOthing will happen for a while until it will all get looser and looser in there and start banging and doing damage so first chance you have is to pop the head up, look at the top of your piston, you'll have your answer right there. replacing piston and rings won't be expensive. You would have had to bring the bike back straight to the dealer soon as you noticed the smut coming out the back. MX don't have any warranty but if it's been like that from day one, a decent dealer would have looked into it and fix it at no charge. Of course if you don"t know much about bikes and stuff you just can't do any of that and that's not your fault. We all had to learn somewhere, some of us the hard way too.

Good luck and get that thing opened up.

Thanks a lot

When I will have it opened up I gonna let u know what my buddy found in it

Do that please, I am very interested in it. That's too bad cause you have an '07 and it sounds like you don'r race it even so the bike should be trouble free after 80-90 hrs.

You've had bad luck but let's see what you find out when it's opened up.

I raced my '06 YZ 450F for 2 full season and never a spat of a problem, I sold it to a novice guy and he race this season and has not done anything else than change the oil still. He is due to open it up I told him though.

I now race my '06 250F (turned into a 290F) bike only had 10 hrs from my wife riding it until I took it over and put the big bore kit in it and now I have about 40 hrs total on it, half of it racing hrs and I am not opening it until I do another full season of racing in '09. BY that time the bike will have about 80 hrs, at least 50 of them racing.

Good luck with your RMZ and let me know for sure.

Oooh, so yuo are an expert

I just started MX 1,5 years ago when I bought my RMZ. Before I'd had a Husqvarna WR 125, and before that a Yamaha DT-50.. Anyway Im 20

I fell in love with MX when I had my Husqi but that was an enduro. So I decided to buy a 4-stroke mx machine. On the other hand I should have opened up the husqi again. Since then Ive been doing MX and I absolutely love it

Last weekend where we went, there was a nice long enduro track, I did not even tried it

I was satisfied with the MX track

though some of my friends did the enduro track many times.

I think Im going to have it opened up in a month. Here in Hungary, cold weather just arrived. But in sand its still okey just cold. Last weekend there was still 13 degrees. Now its 2-3..

When I know sth about my bike's condition I'll let you know!

Thanks for everything! I glad we met

I am not an "expert", rode a lot as a kid. My dad rode as well and he raced snowmobile. He was the manager at a big Yamaha dealer in Canada then. But then life/career took over my life and I didn't ride for 20 years and got back into it 4 years ago when my son was 8. I bought him a bike and took him to a MX school. The very next day I went and bout myself another bike (2 strokes cause that's all I knew growing up) after 20 years of not riding and got back into it. The followiing year having worked on my skills and fitness I bought both the YZ450F and YZ250F 50th anniversary edition as they were yellow like my old YZ back in the late 70's and early 80's. I am 43 now. Race the 450F for 2 years. I race the Veteran Class and rank as an intermediate in MX1.

IN the Vet class you can race any bike size cause it is about the age, you have to be over 40 so there I race my 290F now. I finished the season in 6th place out of about 28 racers so I am not an expert. Just a guy that rides as much as he can! I have a motorhome that pulls a trailer in the back where we have the bikes and all the parts and we just go to MX tracks. WE do a little trail riding when we are tired of waiting for the tracks to open in the spring. I am on the West coast of Canada and winters here are extremely wet, it rains all the time so the tracks have to close. Usually in the winter it satys above 0C but sometimes it goes under a bit. Track normally opens end of February. We rent indoor tracs also in the winter, we just did the past 2 week-ends and that is also pretty cool although the indoor tracks are very compact and dangerous as there is no room to make a mistake, there is always a turn or an obstacle to deal with, no long stretches. Take care kid and enjoy MX and try not to get hurt doing it

dont worry about your bike. If you take care of the bike like you are supposed to do and if you ride it like you said you did then it should be fine. I would check the valve clearences just to see if they are moving at all.

really what it amounts to is how you take care of your bike. I have a friend with a yz250f with 163 hrs who rides the rev limiter all the time and the valves have never move from when he bought it new. all he does change the filter every ride and the oil every other ride. believe it or not.