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280 vs 300 big bore kit

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I know this topic has been beaten to death but I still am having a hard time making a decsion weather to get at 280 or a 300 bb kit for my 09 ktm 250 xc-f. The pros seem to be using the 280 kit. Any opinions?

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What is commonly called a 300 trully is a 280. this can be done with bolt on piston, cylinder etc.

Going to the next level involves maching cases, welding water holes in the head and drilling new ones further out from center etc etc, big job! Several such combos have been built, I have a 314cc version on my bench, don't hold me to this but I think they have done up to abt 325 without stroke.

Then the next level is strokers which have been made up to about 350cc.

TO my thinking those bigger combos may be fine for a lightweight rader who is smooth, the trans is pretty delicate and when you get a bull in a china closet rider carrying some girth who wants to fit a bigger tire it may get expensive

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I've been doing a little more research and the ht racing 280 really is a 280 and the 300 really is a 300. But, the thumper racing 300 is a 290. So if I've got this right I can get a 280, 290 or 300 without machine work on the cases or a stroker. All of them seem priced well and a relative bargain. So, what do I get?? If my info is right Curt Caselli was on a 280 when he got on the podium at the gncc in Unadilla. His best finish all year. Interesting

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To my way of thinking, if you are going to the trouble and expense of a BB why not spend a little more and go with the 320 or better yet the 350.

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I dont think anyone really knows what is in a factory bike........

I went with TR 300 due to things I read on the net vs the other company. If going bigger Im not sure which company i would have chosen.

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I went with the kit from KTM because it came with a new cylinder. That way I have a back up if anything happens. I will be putting it in over the christmas break, can't wait to try it out.

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I dont think anyone really knows what is in a factory bike........

I went with TR 300 due to things I read on the net vs the other company. If going bigger Im not sure which company i would have chosen.

So you went with a 290. That is what I am leaning towards. So how do you like it?

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it runs great, I had a few questions and Travis answered them on the phone or overnite by email. No problems with the kit and it gives it just that little extra low end that it is missing stock. I geared up to 13-50 from 13-52 stock. I also have the KTM dvd for the motor tear down so it was easy. The 2nd time I took it apart and I forgot to lock the crank, but that too was no big deal and it went back together fine. The valves have only moved 001 on the intake.

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Have anyone of you made a bench test before and after bb kit?

I'm definetely going to do after bb istallation, but i dunno yet is it 280sxs kit or 300tr kit... and im after 40 hp's after tuning... so lets see during this winter season what happens here in freezing temp's...

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I've been doing a little more research and the ht racing 280 really is a 280 and the 300 really is a 300. But, the thumper racing 300 is a 290. So if I've got this right I can get a 280, 290 or 300 without machine work on the cases or a stroker. All of them seem priced well and a relative bargain. So, what do I get?? If my info is right Curt Caselli was on a 280 when he got on the podium at the gncc in Unadilla. His best finish all year. Interesting

Sorry, but you're wrong. The TR and HT 300 kits are both 290's.

I'll be getting a 280SXF kit because I want the extra cylinder and Nikasil liner.

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Have you measured the TR or HT kit piston size? There you would have the answer whether its 290 or 300cc.:moon:

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I installed a KTM sxs 280 kit 2 months ago,it was the best motor mod i've made to the xcf.It was fairly easy to do with the KTM cd-rom repair manual.It comes with top shelf parts as well.The power down low is now much better and it did not seem to effect the power at high rpm.I think can't wont go wrong by choosing any quality BB kit it's money well spent.

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Have you measured the TR or HT kit piston size? There you would have the answer whether its 290 or 300cc.:moon:

I've seen multiple posts where Bill from HT stated it was a 290 on KTMTalk.

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Iv got the SXS 300 kit fitted to my 08 250 best money you could spend it makes it so much easier to ride , i think the new SXF 350 KTM are releasing will be the perfect bike

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Iv got the SXS 300 kit fitted to my 08 250 best money you could spend it makes it so much easier to ride , i think the new SXF 350 KTM are releasing will be the perfect bike

300 kit? Is that released yet?

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I've seen multiple posts where Bill from HT stated it was a 290 on KTMTalk.

Both the Thumper Racing and the other guys KTM 300f kits are 81mm pistons and actually 290cc. Thats where the simailarites end. Thumper focuses on issues of the big bore 250 none of the other manufactures do: Thumper has a better sleeve design and ceramic coated CP piston and thats what makes the Thumper Kit the better choice.

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Both the Thumper Racing and the other guys KTM 300f kits are 81mm pistons and actually 290cc. Thats where the simailarites end. Thumper focuses on issues of the big bore 250 none of the other manufactures do: Thumper has a better sleeve design and ceramic coated CP piston and thats what makes the Thumper Kit the better choice.

How about compared to a KTM SXS 280 kit?

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Sorry, but you're wrong. The TR and HT 300 kits are both 290's.

I'll be getting a 280SXF kit because I want the extra cylinder and Nikasil liner.

I spoke to the guys at both HT and TR. HT makes two kits. One is a 280 one is a 300. TR makes a 300 kit but it is really a 290, or so I was told.

Any rate I am ordering the TR 300(290) tomorrow.

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I have the KTM 280 kit in my 09 XCF 250. I'm 210lbs and this bike will pull me anywhere I want to go. I bought the bike with the kit in it already. After test riding a stock XCF 250 and a XC 400 it's not quite as fast as the 400 on the straights but will out run it in the New England tight woods. IMO more power less wieght is always good. The 280 kit puts just the right amout of power to the ground. Whichever kit you go with you will love it, makes a big differance.

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I checked from TR site, the piston size is said to be 82mm (300 kit), so with KTM's 54,8mm stroke it makes 290cc. Does anyone know the sxs280 kit piston size??

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