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stupid 4 vs 2 stroke question

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ive read many magizines, and im pretty much set on getting a yz250f.. my question is though that from the reading of the magazines i cant tell which one accelerates harder. it seems like a 250f usually gets the holeshot in races, but anything else i should know about the 250f.

also one of my friends wants to get an 85 mx bike.. which one is the best in yalls opinion. he has honda bais because he currently has an xr100, but ive heard the the yzs have the best motor :)

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IMO you can't go wrong with either the CRF250R or the YZ250F. Different people have there problems with each but I like both even though I have a 05 CRF250R. Only reason I went with the CRF is that the YZ is more top heavy compared to the CRF. Don't even stress the acceleration. :)

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Don't get a 250f, they have titanium valves which must be replaced about every 25 hours. A 250f will easily beat any 85 in a race. Get a KTM SX125 if you want a good fast bike, the KTM's engine components (piston, clutch, etc) outlast the components of any 250f...

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Don't get a 250f, they have titanium valves which must be replaced about every 25 hours. A 250f will easily beat any 85 in a race. Get a KTM SX125 if you want a good fast bike, the KTM's engine components (piston, clutch, etc) outlast the components of any 250f...

25 hours?? I have over 2500 miles on my WR450 with titanium valves and they still look pretty good, last time I checked about 500 miles ago.... thing runs awsome and I use it for hard dez riding and some dez racing... so it gets abuse. Does the 250 eat the valves or somthing?

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25 hours?? I have over 2500 miles on my WR450 with titanium valves and they still look pretty good, last time I checked about 500 miles ago.... thing runs awsome and I use it for hard dez riding and some dez racing... so it gets abuse. Does the 250 eat the valves or somthing?

That's cause it's a yamaha! :)

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Yeah the 250f's eat valves quicker than 450's because you have to rev the ring off them to get power. 25 hours is still way off the mark for anyone other than a pro rider. You could probably get 50-75 hours probably more, even if you ride it fairly hard IMHO. Like was said before both cr-f and yz-f are good bikes just pick your favourite colour, I personally prefer the yz-f because I like the 5 valve head and I think that it improves durability, but that’s just my opinion. Also if you are after a 2-stroke, the ktm125's are the way to go unless you want a brand spanking new yz125 with the aluminium frame. Every other company has all but stopped cash flow into 125 2-stroke R&D. Just my $0.02.

Now just ignore all of this and go listen to someone who knows what they're on about : :):)

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go with the yzf. change the oil regularly, change and clean the filter regularly, and your valves will last a lot longer. have fun :)

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The five valve design on the Yamaha has less valve seat pressure so the valves will last longer. A lot longer.

The four valve design on the other brands requires more seat pressure to seal effectively, therefore they will wear faster. Especially if you dont keep your air filter clean.

I had an 03 YZ 250F and never replaces the valves and adjusted only once. Had it for a year and a half of hard riding and racing. (somewhere in the neighborhood of 600-700 hours)

My buddy bought an 04 CRF450, has had it for about a year and is on his third set of valves.

Moral: RIDE BLUE :)

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Don't get a 250f, they have titanium valves which must be replaced about every 25 hours. A 250f will easily beat any 85 in a race. Get a KTM SX125 if you want a good fast bike, the KTM's engine components (piston, clutch, etc) outlast the components of any 250f...

Who brought the dork??

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Who brought the dork??

yeah, what's he thinking about, using facts in a discussion. all hail to the mighty (and fragile) 250 4-strokes.!! :):)

seriously, no 250f accelerates very hard. that's why they are good bikes for tight woods, beginners, young girls, etc...

if you want acceleration, get a 450+ or a 250+ 2-stroke.

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Don't get a 250f, they have titanium valves which must be replaced about every 25 hours. A 250f will easily beat any 85 in a race. Get a KTM SX125 if you want a good fast bike, the KTM's engine components (piston, clutch, etc) outlast the components of any 250f...

You just showed the world how little you know about dirtbikes.

Dumbest post I've ever seen on TT, seriously.

Doug

'04 YZ250F

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I read the stuff about the valves in DirtRider. Here is a quote from ONLY4STROKES:

"First of all, you cant always believe what you read in magazines, especially Dirt Rider (their editors arn't exactly known for being the smartest of the bunch). If you honestly read in that magazine that 250F valves should be replaced every 25 hours, I'm surprised you believed it. Its a known fact that four-valve engines (everyone excepy Yamaha) need their valves checked/adjusted every year, while the titanium five-valve design of Yamaha is every two years.

This is what every other magazine except Dirt Rider says. Majority rules here. I've known people personally who own Yamaha's that are six years old and never had a single valve problem. It is possible to go the life of the bike without having to replace the valves completely. Just check and if you need to adjust them if they're ever out of spec. It all depends on how you ride the bike. I'm sure you read that article wrong, because if you didn't Dirt Rider would be getting some serious hate mail."

I stand corrected :)

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no.. we read it right.... there has been a lot of talk about it in the yamaha yz250f forum.. they were really talking about all of the other companies when they wrote that article.. go to the yamaha forum, and ask if that article applies to them, and see what they say

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I read the stuff about the valves in DirtRider. Here is a quote from ONLY4STROKES:

"First of all, you cant always believe what you read in magazines, especially Dirt Rider (their editors arn't exactly known for being the smartest of the bunch). If you honestly read in that magazine that 250F valves should be replaced every 25 hours, I'm surprised you believed it. Its a known fact that four-valve engines (everyone excepy Yamaha) need their valves checked/adjusted every year, while the titanium five-valve design of Yamaha is every two years.

This is what every other magazine except Dirt Rider says. Majority rules here. I've known people personally who own Yamaha's that are six years old and never had a single valve problem. It is possible to go the life of the bike without having to replace the valves completely. Just check and if you need to adjust them if they're ever out of spec. It all depends on how you ride the bike. I'm sure you read that article wrong, because if you didn't Dirt Rider would be getting some serious hate mail."

I stand corrected :)

I have an 01 WR426 with about 5,000 miles on it. Hard desert riding for the first 2,000 (the guy who owned it before me raced).

I have never adjusted the valves, every time I check them they are in spec.

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back to the original question, it depends on the rider. most 125 2 strokes have more overall power, but it's not seen until high in the power band. Most people will say a 4 stroke accelerates faster, probably because the power kicks in at a lower rpm and it has more of a flat power curve making a smooth power transition. 2 strokes are abrupt power but they accelerate like crazy also.

4 strokes are a lazy bike, anyone can ride them. It takes some work and practice to ride 2 strokes good. If you don't mind cost and maintenance then 4 stroke is ok.

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