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280 kit?

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I am thinking about getting a 280 kit for my XR250 from XRs only. how much will this cost, and how much power would I gain from it??? also, could i still use regular 87 octane gas with it??? thanks

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I had a '97 with a 280 kit in it and it was GREAT!! :cry: Really woke the bike up and had more grunt throughout the motor. It is worth the money if you are set on keeping the bike. I assume the kit comes with all the goodies, pipe piston,etc. you sould always be running the highest octane pump gas you can find regardless of the motor size.

:cry:

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you would only use race fuel if you were running a higher compression piston and the motor mods to go with it.

There are several companies which sell 280 kits , i think they are actually 277cc's JE pistons , Wiseco, to name a couple , you might want to concider buying the parts from an outfit like Thumper racing or Xr's only so that later down the line you can get a gasket, rings or wrist pin. It may me more complicated buying it from a dealer unless you know what your buying.

stu

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would I still get a noticable power increase if I didn't get a higher compression piston to go along with the 277cc kit?? also, would I need a bigger carb to go along with the increased ccs or would the stock one work??

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think you can get a 10:1 piston, would only need premium pump gas. you would also need to rejet the carb, not get a new one.

I have the 280 in mine and love it :cry:

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I am going to buy my cousin's 2002 XR250 with only like 20 hours on it for $2500 which is a steal, and I don't want the extra weight of the 400. how much HP do you think a 280 kit with the stock compression would add?? also, if I wanted to get the head ported and polished, how much HP would that add?? would getting it ported and polished be worth the money??

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Yes, I feel a 280cc kit is worth it. Don't be afraid to use higher than stock compression. That's what helps wake up the motor. You can still use 93 pump gas.

Port the head at the same time. You can basicly clean it up yourself, and your not supposed to polish. Use a fine grit or the fuel tends to stick to the wall.

Adding a bigger jet in the carb and modding the air box will finish the job off real nice. Remove the exhaust baffle.

As I look back, souping the xr250 was my favorite project. Maybe it's because it was my first. Maybe because it is cheap and simple. Either way it seemed way more powerful.

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I am going to buy my cousin's 2002 XR250 with only like 20 hours on it for $2500 which is a steal, and I don't want the extra weight of the 400. how much HP do you think a 280 kit with the stock compression would add?? also, if I wanted to get the head ported and polished, how much HP would that add?? would getting it ported and polished be worth the money??

Personally, I would save my money on the port job and put it into the Thumper Racing 300cc kit. I would also get a 30x32 mm Edelbrock Carb with pumper from Barnum's Racing. Put on a ProCircuit pipe and GO ! Be sure to beef up the clutch to handle the extra power and torque. The 300cc kit is a HUGE power difference. Even over the 280 kit.

Cher'o,

Dwight

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You should just get an XR400! :cry:

It isnt worth the hassel getting a bigbore kit for a 250 when you can get a 400, Their so similar to, But the 400 feels that much better to ride.

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Dwight rode these bikes (XR's of many various incarnations)and knows them in and out. He would not give you information on a set-up that he did not believe was worth the investment nor would he give you information on something that would be a time bomb. He is after all and foremost a enduro rider who lives and dies with reliability. His opinion deserves respect IMHO.

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yeah but wouldn't the 300 kit make the bike way less reliable???

Actually no, It may indeed make it more reliable in the long run if you use a high grade Motorcycle specific Synthetic racing oil and beef up the clutch (weak link). You will be turning less rpms with the 300 kit. The kit from Thumper Racing has a special wrist pin that doesn't flex and wear out the upper rod. With the 300 kit it will have gobs of torque. Who cares about Horse Power. Mine would top out at about 78-82mph ( different bikes ) Stock gearing. I would recommend though a 45 or 46 T rear sprocket to take better advantage of the extra torque and power. Go with a UNI filter also, Flows better mainly because of the cage. I won many championships on modified XR250s. I built them all the way to 340cc. The 315 - 320cc are best but the 300 is only a smiggen behind. BUT with the 315 or 320 kits you MUST run 100+ octane. On the 300 kit you can get by with 93oct. with 1 oz of octane booster per gallon. I also like to run 3 oz of Marvel Mystery Oil per 5 gal. to help cushion the valves and lube the carb slide. I have built some pretty good XR400s ( XR440 ) but I find that the Modified XR300 is way more fun for a average sized rider. ( I am 5'9", 170 lbs. )

Be sure to go with the .40kg fork springs from WER and get them to revalve both ends.

HAVE FUN !

Dwight :cry:

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I also like to run 3 oz of Marvel Mystery Oil per 5 gal. to help cushion the valves and lube the carb slide. Dwight :cry:

Dwight:

Think some Marvel Mystery Oil would be a good practice to start on my new CRF250R with its known valve problems? You'd do it, right? Apple a day....

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I personally would keep the comperssion as low as possible up to 10:1 or maybe 11:1. just incase you are in a bind and need to run low octane.(ya never know.) unless this is going to be a strickly race bike. or you know that you will never have to ride somewhere where you can't get high octane.

I would consider anything that Dwight says to be considered expert advice.

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