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new to 4 strokes


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I was looking to get a 2006 or newer yz250f. Right now i ride a 2006 yz125 and was thinking to try out a 250f. I mostly ride track and some trails. I am very good on maintence with all of my bikes. I ride usually 2-3 times a week for about 2-3 hours of riding time. How often would i have to rebuild the top end? When i do have to rebuild it, do i have to get valves, cam chains, valve springs, and everything else that a two smoke doesnt have? What would i need to buy when i rebuild it? How often? How many hours can you go on valves? What more do i need to do manitence wise than the yz125?

Also do yz250f's really feel any different in weight from a yz125. Are they easier to ride than a 125 two smoke? Are the yz250f's great reliable bikes? What do i need to look for when biking a yz250f?

Any help would be great!!

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Man, you want it all in one post. Ok, here goes:

1. Do the maintenance first. That means get an hour meter and change the oil at 5 hours... filter then or next oil change. Best thing you can do to protect the valves is add a Flo single foam filter on top of a stock or TwinAir filter. When I started doing that, my valve maintenance went to -0-. Clean those filters too and oil them and grease the lip. If you get a used 06, ask if the valves have been changed out, there was a recall, and look at the VIN because the shop will put a punch mark over the numbers. Book calls for a top end at 50 hours, but I've gone way over that, but I trail ride mostly. Cam chain is only $17.00 and easy to change. It will take out the crank and it will jump time and take out the valves if it jumps, so change it. Also change the chain sliders and oil pump gearrotors. Grease all bearings and threads regularly, that especially means suspension linkages. Yamaha sells the parts without having to buy a kit and waste your money on stuff you don't need. Use stock head gaskets.

The 4-stroker is heavier, but the throttle response is what I buy this bike for. My 300 KTM will rip right out from under me if I let it, but it has to be at the right rpm. The 250F has snap as soon as you nail the throttle. It doesn't like to be bogged down too low though. Power comes in around 5000 and sings all the way up past 10,000. Don't pin it and leave it at the rev limiter either, that will kill the crank and lock it up. Use that steep torque curve, learn how to ride in the range where that curve is rising and it will reward you with passes every time. Just because it will run at 13,000 doesn't mean you have to take it up that high. Add-ons, bar risers for a taller rider, Guts Racing tall soft seat foam for much longer stays in the saddle, skid plate for off-road, bark busters too, some like radiator guards. Good luck.

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Adding to the great input already given, the big learning curve for me going to a 4 stroke was the engine braking and added engine inertia while cornering and jumping. That will take some getting used to.

Maintenance: I change my oil every 300 miles or earlier on a 4 stroke. On my 2 stroke, well, you could literally forget about it for a long time and the bike will still shift and run as if the oil change was done seconds ago, ha.

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Some really good info here. I would agree maintaince is the key thing for a 4 strokes life. I raced a 04 YFZ450 quad in cross country for about 4 yrs. I raced A class and pro class. We would do a top end, piston, rings,etc. after every season and just check the valves every few races. Oil was changed after every race, filter cleaned after every ride. And never really banged off the rev limiter much, not reallly needed in xc anyways. When I rebuilt the head, valves, springs, etc. I had four years of hard xc racing, gncc, and plenty of riding and practicing, along with alittle flat track racing. I bought it from some buds that also raced xc and they had it for a year. Now that I am out of quads I just got into bikes and bought my buddies 05 YZ250F. I have rode this bike from the day he brought it home from the dealer. He raced it alil but mainly just rode. The oil has been changed regularly and the filter always cleaned. The bike has never had a top end rebuild and still runs like the day it was new. So for me ive had a great experience with yamaha and the reliability of them. For me ive always said, take care of them and they'll take care of you. But i enjoy working on them and prolly maintaince them alot more then whats nescessary.

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Since Link touched on it, I'll add some more. I like cutting across corners. I come in hot and to the inside, downshift part way in, and time it so I do a two wheel drift into the berm, then pin the throttle and let it grunt out of the turn. Do it right, and you don't even touch the rear brake. The rear will drift out a little as its turning and set you up for a perfect turn. You gotta choose which turns, soft berms work best while hard pack flat turns aren't quite the same.

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