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Which Big Bore Kit?

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This winter will be time to do a little work on my son's 01 250F I'm pretty sure we want to add a big bore kit. I'm undecided as to which to buy. We agressively ride mostly rocky tight single track in New England. He'd like some extra bottom. What are the advantages and disadvanges of the stock vs 262 vs the 290 kit? Does the 262 give you much more bottom than stock? How reliable is the 290? Is it worth paying the extra money for the 290 kit over the 262? Love to here from someone who has riden both.

Thanks!

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This winter will be time to do a little work on my son's 01 250F I'm pretty sure we want to add a big bore kit. I'm undecided as to which to buy. We agressively ride mostly rocky tight single track in New England. He'd like some extra bottom. What are the advantages and disadvanges of the stock vs 262 vs the 290 kit? Does the 262 give you much more bottom than stock? How reliable is the 290? Is it worth paying the extra money for the 290 kit over the 262? Love to here from someone who has riden both.

Thanks!

If your son wants to race MX in the 125 class the 262 is legal and the 280 and up aren't.

The 262 & 280's are bored & plated = good

The 290 is bored and has a liners, liners = heat = bad,,, IMO(not that my O means squat)

:thinking:"I think" the 290 requires hi octane fuels but don't not having one I can't say for sure.

I run a 280 from Thumper Racing and just love the thing, over a years worth of abuse and still going strong. :cry: I can tell you the 280 I have adds pull all across the board and pull each gear so much stronger but will take a lil over rev away but It more than worth the trade off. :cry:

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Have to agree with mxoldtimer, if your young lad likes to rev the bike he may miss the very top and the 280 doesn't rev as quick as standard. But the rest is awesome. :cry:

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I have the 262 kit on our 250F's. You need to run premium with it as the compression ratio is bumped up to 13.5:1. They also tend to run hotter from the higher compression so idling time will be reduced before boil over. I went 262 as it makes the same hp as the 280 but does it at less weight. Less weight means quicker revs. And they are rev snortin monsters with bad attitude now. :cry:

When you do the overbore make sure to add a set of hotcams. That was the single biggest improvement done to my kids bike according to him.

Dont forget to cut the backfire screen out, cut the rear wall of the airbox down flush with the fender, gap the plug at 0.040, and run a decent exhaust pipe. They all contribute to more hp.

I forgot to add earlier, wrap the header and midpipe with header wrap. It also helps to make more power too. And the shock resevoir and carb stay way cooler with it too.

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I put the 262 kit in an otherwise stock WR250. I just got back from doing 50 miles on it. It makes the bike much more fun to ride. I would say it puts about 2 to 3 horsepower more across the board according to my anus dyno.

I don't see any down side to it. The bike is much more fun to ride.

I bought mine from Forward Motion for 365.00. One of the tuners frequents this board and answered all my dumb questions.

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When you do the overbore make sure to add a set of hotcams. That was the single biggest improvement done to my kids bike according to him.

Do the Hot Cams have the auto decomp or do you need to go back to Man.?

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They come with the auto decomp (but make sure it states that). You can get them cheaper on ebay than anywhere else. I have gotten both sets for our 250's from woodwardspecialties.com on there. Buying them in a set saves the shipping on one of the cams.

whats nice about getting the intake as well is that it is adjustable for timing +/- 5 degrees. advance it 5 for a lot of grunt down low and retard it 5 for WOT performance. It lets you time it for where you are riding. :cry:

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Beezer,

Do you have a website address or phone number for Forward Motion. Sounds like the 262 kit would be the best for him.

Thanks!

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If your son wants to race MX in the 125 class the 262 is legal and the 280 and up aren't.

The 262 & 280's are bored & plated = good

The 290 is bored and has a liners, liners = heat = bad,,, IMO(not that my O means squat)

:thinking:"I think" the 290 requires hi octane fuels but don't not having one I can't say for sure.

I run a 280 from Thumper Racing and just love the thing, over a years worth of abuse and still going strong. :cry: I can tell you the 280 I have adds pull all across the board and pull each gear so much stronger but will take a lil over rev away but It more than worth the trade off. :cry:

word.

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I just installed an Forward Motion 262 kit a few weeks ago. What a difference. I sent them the cylinder, head, piston and upper bearing. My 01 cylinder looked new. I would pay the 50.00 to have them soda blast the head, clean, check and re-shim the valve. The best 50 I have spent. It took about 7-8 days from the time I sent it in until I got it back. And Rich will answer all your "dumb" questions. He answered mine. I know there are several guys putting out these kits, but Rich and Eric montior TT and do great work!

:cry: I just got back from some desert riding and some monster hills. The bike pulled up these big hills like never before. Just my 02 cents...

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