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250 port and cam desighn

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I have changed the 250 port desighn entirerly the stock port flowed extremly well but was simply to large Ktm has a tendency to make there ports large the engineers are paying to much atension to flow numbers and getting very low velocities its the old hog it out therory and make it flow there giving up a lot hp .also there cam profiles are very long and not agressive in the higher lifts im also going to fix that .

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Are yout referring to the 11-12s? I had a look a while ago and come up with nothing , Couldn't find anything available .I also put a post up and got zero replys .

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yes im referring to the 2012 250 im just getting started with it but i have discussed it with other builders and tuners and they say the ktm always lacks torque and is very flat .i beleive all that can be fixed with the changes in the cylinder head and cams.the 350 comes next.

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I guess this finally means that KTM has gone mainstream when it draws the attention of someone like Ron :smirk: The 250F is the "oldest" design in the KTM lineup which was introduced in 2005. Despite some updates with EFI for 2012 it is still the same basic design and KTM knows that - so for 2013 (just a few months away :bonk:) we will see a completely new 250F engine. First official glimpse will be the introduction of the MX2 GP bikes pretty soon. Lots of rumors at the moment over here, but I assume we will see a more "current" head&port design together with a new bottom end (350F like). A RHC 350F though would be something I'd be highly interested too; maybe something like the complete Honda 250F heads for us guys abroad? If they are affordable from KTM.

Michael

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Dumb question but Why are the pro lites guys bikes so strong? Its not uncommon to see a ktm leading to the first corner. I would have thought that would be the perfect example of hp at play. That being as pros are all at similar skill levals hp would shine through, If you know wha i mean.

Ron are you making a hp upgrade kit? head an cam package? Or are we going to be able to get cams from you to work with or stock heads?

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Definately exciting times with these new KTM head designs. These are going to be some light engines correct? Going to outdate the current dual cam configurations pretty quick I would say. I would love to be a fly on the wall while Rons flowing these things too I bet one could learn a lot!

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getting to the corner first is still about traction and rider reflexs .In most cases having the hp that we can make from a 250 does not do much for the elite pro riders but having a good power curve for the rest of us sure makes it eazyer to ride .being able to jump out of a corner like a 450 with lower speeds for example.the hondas always seem to get the hole shots in the out door nationals where the starts are longer .

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I pretty much spent three years full time on the 250F from 2007-2010, lots of time on the flow bench and Dyno LOL.

The current intake port shape is very close to the best design for 8-14,000 RPM and my best results have been with the 2009 cams set with more overlap. Wiseco Hicomp pistons and the piston to head clearance set 0.9mm.

We have had great results with the 2006 model and the Crower Cams, early on but as we got the head to flow better we didn't need the duration.

We tested a whole bunch cross-sectional areas the KTM head has two round ports and their easy to get at to work on with the guides out.

PM me and I can give you some lobe centers and cross-sectional area measurments that worked for us recently.

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were you able to ever get the ktm past 46 hp and 22 pounds of torque im looking for power from 5000 rpm to 13000 rpm

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were you able to ever get the ktm past 46 hp and 22 pounds of torque im looking for power from 5000 rpm to 13000 rpm

With our pump fuel rule here we where and still are stuck at 40-42 mark, I have run our motors with U4.4 just to see what we are missing out on and they jump into the low 44;s with out any ing timing changes.

the stock bike ran 34.85 hp on our dyno, it seems to have topped out at +7 over stock.

up to 2010 the we never saw better from the world or us team bikes.

One thing to watch out for is the crank drag we built 6 new motors with same piston, comp, ing,cams, and basic head work and they ranged from 38.5 to 41.2 on the dyno and the bikes in the thirtys were religated to Practice Bike duties ( thinking the heads were not as good). 20 hours later the Practic bikes were the HP kings in the 42.s with only a fresh piston same settings.

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i was stuck @ the 42 hp with the honda for several years my carbed bikes made as much as the 2010 fuel injected bike.the best of the best oxy fuels that i have had made avaiable to me heres in the us are only worth 1.5 hp @ best in a 250 .I no what you mean about getting an engine loosened up you cant do it on a dyno it seems like they always pick up some power after they have been run on the track a bit and then a new piston ring installed our arena cross bikes make 45.5 even after several races we can freshen them and get over 46 for a bit.the amasing thing is the torque 2 over 22 pounds and the power curve holding on for so long past 13000 rpm.im quite sure that i could make 47 with a louder pipe as we are passing the the sound test .This is what im hoping to acheive with the KTM .

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both arenacross bikes got tuned up before grand rapids just tuning on the dyno they were making 45.5 hp when we were done .

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both arenacross bikes got tuned up before grand rapids just tuning on the dyno they were making 45.5 hp when we were done .

&%$#@!!!!&^%$$#$%^&*^%$ What does this mean for the 350? Have you done one yet? Want to??

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I havent had a chance to graph the stock cams yet but a cam company ran them through there tester and gave me the cam profiles from what im looking @ is there way to long of duration and a very lazy profile the ktm valve train with its large radiused followers are capable of a much more agressive lobe even moreso than a honda .Both the ports and cam desighn seem to be old school engineering make the port flow lots of air and forget about velocity and ad more duration and lift to the cam that works to a point .I have added duration to some of our cam profiles to tone the power down a bit they will produce less peak and a softer delivery but usally good over rev and this works good for slippery tracks .A ktm 350 should eazly make low 50 hp numbers .i would think that the 350 would make the same peak numbers as a stock 450 with around 4 pounds less torque and very good over rev and would be eazy to ride and less tiring .

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I see KTM produces a intake CAM power upgrade kit w/ the option of adding exhaust to the kit. there is also a factory engine kit which includes a NEW head piston connecting rod and intake cam. This is for the 11-12 250SX-F

Edited by BLUS7RK

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I was referng to the 250f. Is there a 38-40hp reciepe?

I read MXA a while back when they rode searles bike and said it had a bigger intake and stock exhaust cam.

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