290 kit or 450??

Anonymous (not verified)
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Anonymous (not verified)
Edited Date/Time 1/26/2012 11:59pm
have a stock yz250f. love the bike been on 4strokes since 05. seems like sometimes i could use a little more power. example one of the tracks i ride has a big jump right out of a corner i can make it but it just seem like the guys on a 450 no effort at all. im 180 5'11 would a 290 kit give me the extra umph i need ? or should i just get a 450? and no i dont want to go back to a 2 stroke 250 . already tried that i dont need to ride a rocket on a track. im just a weekend play rider thanks
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mxb2
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mxb2 5/31/2011 8:30am
5/31/2011 8:30am
My bubby put a big bore kit on his 2010 kawy 250f with a fmf megabomb pipe,4.1 full system, he 5 11, 205lbs, sed its great the 250 was nt enough and the 450 was to much, and wanted the bugs worked out of the new ktm 350,and did nt want wdrop 8 grand.
T-Fish
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T-Fish 5/31/2011 9:55am
5/31/2011 9:55am
Buy a 125, work on your corner speed, then get back on that 250f and huck that double no problem.
motomental1
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motomental1 5/31/2011 11:53am
5/31/2011 11:53am
T-Fish wrote:
Buy a 125, work on your corner speed, then get back on that 250f and huck that double no problem.
i have no problem with the corner or making the jump. like i stated it just seems like the guys on 450s dont have to bump throttle stops to clear it. just wanted some input from guys with big bore 250s. i love my 250f besides maybe just alittle more power.
mxb2
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mxb2 5/31/2011 12:07pm
5/31/2011 12:07pm
T-Fish wrote:
Buy a 125, work on your corner speed, then get back on that 250f and huck that double no problem.
motomental1 wrote:
i have no problem with the corner or making the jump. like i stated it just seems like the guys on 450s dont have to bump...
i have no problem with the corner or making the jump. like i stated it just seems like the guys on 450s dont have to bump throttle stops to clear it. just wanted some input from guys with big bore 250s. i love my 250f besides maybe just alittle more power.
Like i said, my buddy loves his big bore kawy!

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motofab36
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motofab36 5/31/2011 12:12pm
5/31/2011 12:12pm
mxb2 wrote:
Like i said, my buddy loves his big bore kawy!
actually you said "bubby"................jus sayinTongue
mxb2
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mxb2 5/31/2011 12:13pm
5/31/2011 12:13pm
mxb2 wrote:
Like i said, my buddy loves his big bore kawy!
motofab36 wrote:
actually you said "bubby"................jus sayinTongue
My bad lol.
motomental1
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motomental1 5/31/2011 1:19pm
5/31/2011 1:19pm
lots of choices for big bore kits. any recomendations? and might as well do a pipe.
mxb2
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mxb2 5/31/2011 1:26pm
5/31/2011 1:26pm
motomental1 wrote:
lots of choices for big bore kits. any recomendations? and might as well do a pipe.
Whats the choices your looking to decide on?
motomental1
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motomental1 5/31/2011 1:40pm
5/31/2011 1:40pm
JE, Athena, magnum or buy a use cylinder have it bored and plated then get a wiseco piston kit 83mm. which seems like a hassle. when you can get a complete bolt on kit.
mxb2
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mxb2 5/31/2011 1:47pm
5/31/2011 1:47pm
athena is good, ice cube also.
mxb2
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mxb2 5/31/2011 2:08pm
5/31/2011 2:08pm
NP man, keep us posted when you get it together!
RNagy052
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RNagy052 5/31/2011 6:55pm
5/31/2011 6:55pm
Before you buy a 450 see if you can ride one of your buddies first. I have been on 250F's since 06, in 09 I went out and bought a 09 RMZ450 because I was thinking the same thing you are. I spent a year hating life on that 450 and went back to a 250F. The 450 now sits in the garage and collects dust for the most part. I only ride it maybe once every 2 - 3 months.

i have a 09 YZ250F and like it a lot better than my 450. I was thinking of putting a 290 kit on it, but went with the Yamaha GYTR high compression piston instead. I just finished putting the new piston and rings in tonight. Going to take it to a track this weekend where you drop down into this pit (corner) and when you climb back out it you actually double right out of the pit (corner). I could do it before on my 250F, but not every lap, hopefully the new piston will give me just enough extra to make that jump a lttle easier to do.

There are some good threads on the big bore kits in the Yamaha section of the Thumpertalk forum. if you ever visit there.
motomental1
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motomental1 5/31/2011 8:27pm
5/31/2011 8:27pm
RNagy052 wrote:
Before you buy a 450 see if you can ride one of your buddies first. I have been on 250F's since 06, in 09 I went...
Before you buy a 450 see if you can ride one of your buddies first. I have been on 250F's since 06, in 09 I went out and bought a 09 RMZ450 because I was thinking the same thing you are. I spent a year hating life on that 450 and went back to a 250F. The 450 now sits in the garage and collects dust for the most part. I only ride it maybe once every 2 - 3 months.

i have a 09 YZ250F and like it a lot better than my 450. I was thinking of putting a 290 kit on it, but went with the Yamaha GYTR high compression piston instead. I just finished putting the new piston and rings in tonight. Going to take it to a track this weekend where you drop down into this pit (corner) and when you climb back out it you actually double right out of the pit (corner). I could do it before on my 250F, but not every lap, hopefully the new piston will give me just enough extra to make that jump a lttle easier to do.

There are some good threads on the big bore kits in the Yamaha section of the Thumpertalk forum. if you ever visit there.
i did ride a cr450 once at a different track. liked the bike but never got in my confort zone. the power was just unreal. but i only spent about an hour riding it. still seemed like i could get in trouble with that much bike. gonna stick with the 250f just may have to try some bolt on power.
mx5471
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mx5471 6/1/2011 6:30pm
6/1/2011 6:30pm Edited Date/Time 6/1/2011 6:34pm
From experience,I disagree with anyone that tells you to go with the athena kit. They are junk. I put one on a Yamaha 125 with the guidance of an ex professional supercross mechanic. It lasted 2 races before it destroyed it self and the motor. Exhaust valves didn't last 1 moto before they crashed,and you can't get parts,just a new kit. They do offer a new head,but you have to machine it. If you are slow and want more power,maybe,but if you are slow you don't need more power. Stay away from Athena,and have your original parts modified by someone who knows what they are doing. It won't cost anymore.
OUMX117
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OUMX117 6/7/2011 7:05am
6/7/2011 7:05am
Cylinder Works makes good Big bore kits. I have the 478cc kit on my 09 YZ450F. Motor is nice and quiet (engine noise wise not exhaust wise) and runs very very well. Keeps my 6'4" 200lb ass in the hunt on the start stretch with those light guys on their stock 450's.
williamsmotowerx 6/8/2011 12:12pm
6/8/2011 12:12pm
If you do a big bore without porting you won't be happy.

Stock head on yzf250 can't supply the flow a big bore needs.

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