HP built me a last gen 250 Sxf and on his dyno peak hp was 52! This was a 270 jug, modified head, Vortex ignition and R and D throttle body. The power is awesome and pulls hard all across the power curve. If you are thinking about it, do it!
Finally got my 270cc kit done on my 21 250sxf and on the dyno, with all of my mods it was putting out 49hp on pro6, cant wait to ride it. Super happy so far!!
If you get to do a bit of cylinder head porting as well there will be even more improvements to be had. Increasing the bore size moves the cylinder wall away from the intake valves and the extra distance improves the CFM at all lifts. The improvement in air flow is significant.
We will see, the new ktm head is quite good, it's a clone of our former race head. I haven't quite wrapped my head around some things in 350 vs 250, as the 350 doesn't flow much more but has much larger valves, the restriction is moved to the inlet boot of the head but it still makes more HP...same on most 450's, modern 250's flow nearly the same air.
@HPRaceDevelopment if you can handle the math, the cfm requirement of all the different capacities bikes are pretty similar we were crunching numbers one day trying choose a throttle body size it didn't seem to make sense that the 250f and 450fs ran the same sizes. But you looked at the cfm requirement for the revs the motor spends the most time at it would add up to the magic numbers we always swapping between.
@HPRaceDevelopment somewhere around there. I remember doing it back a while and we ran 41mm FCRs on the 450s and 250s based on track testing feedback and dyno. Some of the data available at the time backed up the average, not peak rpm ranges. We would at the time have some input from friends in the Cosworth/ F1,F3 feild, and was a major rabbit hole... it is still to this day.. For sure I spent some time thinking and feeling around for knowage... one very smart Japanese guy I worked with told me something when I may have pissed him off with too many questions .... he asked me to stop thinking you're driving the bus .... and that working in the performance feild was more like walking along the sea side and comming apon a beached whale 🐋 and thinking your going to nudge it with a stick and have it turn around and back in the ocean.... and watch it swim off.... you stand there long enough and keep poking you will ether learn something or keep walking along the beach until you stumble onto the next adventure. Once I got to talk with a famous movie director on that day had just wrapped up filming a movie and asked yet another dumb question..." When will you finish editing it, and will it be released?" He said well you never really finish editing these things.... the studio or the financial situation always winds up with it being taken off you and released. He went on to say that's why you see directors cuts 20 years later..... you never stop thinking about how you could make it better. At the time, I thought that's the exact way it is for me and the development of race bikes.... 😀
@HPRaceDevelopment You see much fluctuation between stock bikes? Hear all bikes can be as much as 1-2hp different. Machining of parts, proper break-in etc.
@@Davido50 Little bit. Usually within .5 hp My dyno has been slowly getting slightly lower with time. Not sure whats up but soon we are gonna redo bearings - and do it on back to back same bike so we know if they change anything
Have you ever tested the loss or gains from water pumps. I would think in this day of magic pixies controlling ecu that cooling could be controlled electronically wirh no power loss pushing water. Although i have zero clue to how much power it can draw
I shot a video on it but decided not to publish. I think we will publish a video on it at some point. If you wish to electrically pump the same fluid rate as a mechanical pump it will cost you the same power loss - if the two pumps are equally efficient. The power losses just come from generation via the stator - no free lunch in the real world. The electric pump adds weight as well - a negative but - I do believe there are some positives and one in particular we will never publish but that has nothing to do with cooling system
What non star yamaha has been even remotely competitive since 2016 in outdoors? The star bike is rumored to be built/designed by cosworth - it shares next to nothing with a production bike@@adriangalvez5104
@@adriangalvez5104 mxgp factory teamw as running a star engine they have basically no rules other than cc so they can do more ktm group bikes are for sure much better than american ktm group bikes in mxgp
Not sure the best way to contact yall, but was wondering if I get the 270 big bore and have a vortex x10 ecu, do I just purchase a map from yall, or do I need to purchase a GET ecu? running a 23 gasgas ex250f
@@___asd159gh43 If the bike is stock with no mods, the low end of OEM ecu’s is about as good as anything…I’d suggest staying stock. If you start doing mods, then ecus’ have a lot of reason to be used
@HPRaceDevelopment i appreciate it! If i did yalls cams, would that let me tractor up some stuff more or am i getting into "just get a new bike" territory? I love the weight to power but some of Hells Revenge in Moab just makes it chugg hard and im not sure of the best solution
I am interested in having my 21 250xcf done. What is the process? Di I send you the head and cylinder? Bring you the bike. I would like some more information please.
Thats why they telling a big bore adds low down power buth sign off at high rpm its because they getting lean on that rpm range. Afr 12.5 is normal target where they make best hp.
HP built me a last gen 250 Sxf and on his dyno peak hp was 52! This was a 270 jug, modified head, Vortex ignition and R and D throttle body. The power is awesome and pulls hard all across the power curve. If you are thinking about it, do it!
Cant wait to get my 270 kit on the dyno, just waiting for my head to get done
Those are terrific, reliable gains. Looking to grab leftover '23 KTM 250SXF or '24 KTM 250SXF soon. -Ohio
Finally got my 270cc kit done on my 21 250sxf and on the dyno, with all of my mods it was putting out 49hp on pro6, cant wait to ride it. Super happy so far!!
our kit?
@@HPRaceDevelopment yes sir!
Didnt trust any other ones
Well wasnt your whole kit, i just got the piston from you
Love your work, that piston, very nicely done , CP great products, industries bests, Rods also.
CP is awesome stuff. Can't wear out the KTM to easily! Lol That's way to go though. -Ohio #Maximaoils #RangerTremor
If you get to do a bit of cylinder head porting as well there will be even more improvements to be had. Increasing the bore size moves the cylinder wall away from the intake valves and the extra distance improves the CFM at all lifts. The improvement in air flow is significant.
We will see, the new ktm head is quite good, it's a clone of our former race head. I haven't quite wrapped my head around some things in 350 vs 250, as the 350 doesn't flow much more but has much larger valves, the restriction is moved to the inlet boot of the head but it still makes more HP...same on most 450's, modern 250's flow nearly the same air.
@HPRaceDevelopment if you can handle the math, the cfm requirement of all the different capacities bikes are pretty similar we were crunching numbers one day trying choose a throttle body size it didn't seem to make sense that the 250f and 450fs ran the same sizes. But you looked at the cfm requirement for the revs the motor spends the most time at it would add up to the magic numbers we always swapping between.
@@rossmcwatters2716 that calc is somewhat true - a 250 at 15k is a 450 at 8k.
@HPRaceDevelopment somewhere around there. I remember doing it back a while and we ran 41mm FCRs on the 450s and 250s based on track testing feedback and dyno. Some of the data available at the time backed up the average, not peak rpm ranges. We would at the time have some input from friends in the Cosworth/ F1,F3 feild, and was a major rabbit hole... it is still to this day.. For sure I spent some time thinking and feeling around for knowage... one very smart Japanese guy I worked with told me something when I may have pissed him off with too many questions .... he asked me to stop thinking you're driving the bus .... and that working in the performance feild was more like walking along the sea side and comming apon a beached whale 🐋 and thinking your going to nudge it with a stick and have it turn around and back in the ocean.... and watch it swim off.... you stand there long enough and keep poking you will ether learn something or keep walking along the beach until you stumble onto the next adventure. Once I got to talk with a famous movie director on that day had just wrapped up filming a movie and asked yet another dumb question..." When will you finish editing it, and will it be released?" He said well you never really finish editing these things.... the studio or the financial situation always winds up with it being taken off you and released. He went on to say that's why you see directors cuts 20 years later..... you never stop thinking about how you could make it better. At the time, I thought that's the exact way it is for me and the development of race bikes.... 😀
Great video! What do you recommend for break in process for brands new engines and fresh rebuilds?
Great question - check back for a video on this!
Was wondering if you have ever ran a 2022 Ktm 150sx on the dyno? Want to know how it compares to a stock 250f.
In stock form, maybe 37-38 on a good one.
@@HPRaceDevelopment thats terrific 💯
Hard to beat KTM!
@HPRaceDevelopment You see much fluctuation between stock bikes? Hear all bikes can be as much as 1-2hp different. Machining of parts, proper break-in etc.
@@Davido50 Little bit. Usually within .5 hp
My dyno has been slowly getting slightly lower with time. Not sure whats up but soon we are gonna redo bearings - and do it on back to back same bike so we know if they change anything
Have you ever tested the loss or gains from water pumps.
I would think in this day of magic pixies controlling ecu that cooling could be controlled electronically wirh no power loss pushing water.
Although i have zero clue to how much power it can draw
I shot a video on it but decided not to publish. I think we will publish a video on it at some point. If you wish to electrically pump the same fluid rate as a mechanical pump it will cost you the same power loss - if the two pumps are equally efficient. The power losses just come from generation via the stator - no free lunch in the real world.
The electric pump adds weight as well - a negative
but - I do believe there are some positives and one in particular we will never publish but that has nothing to do with cooling system
Can you just replace the cylinder with a 350 and have a 350? Or do the parts interchange?
@@barnescycle no different rod, crank, and head
Kinda off topic but im ur opinion which oem has the best 250f engine to be build as a race speck engine for high hp to be raced at a national.
KX or KTM Group bikes
@HPRaceDevelopment interesting, i wouldn't thought it wouldve been yamaha since star yamaha has the fastest bikes rn.
What non star yamaha has been even remotely competitive since 2016 in outdoors? The star bike is rumored to be built/designed by cosworth - it shares next to nothing with a production bike@@adriangalvez5104
@@HPRaceDevelopment does this all share with the yamha 250 from mxgp?
@@adriangalvez5104 mxgp factory teamw as running a star engine
they have basically no rules other than cc so they can do more
ktm group bikes are for sure much better than american ktm group bikes in mxgp
What compression ratio youre 270 kit have?
@@bernardvanderveen7656 Pump gas friendly same as stock
Not sure the best way to contact yall, but was wondering if I get the 270 big bore and have a vortex x10 ecu, do I just purchase a map from yall, or do I need to purchase a GET ecu? running a 23 gasgas ex250f
If you run the vortex (Im sorry ;)) you can just turn the dials richer.
@HPRaceDevelopment would you suggest buying a GET instead of the vortex? Mostly looking to get low end gains for mostly trail riding.
@@___asd159gh43 If the bike is stock with no mods, the low end of OEM ecu’s is about as good as anything…I’d suggest staying stock.
If you start doing mods, then ecus’ have a lot of reason to be used
@HPRaceDevelopment i appreciate it! If i did yalls cams, would that let me tractor up some stuff more or am i getting into "just get a new bike" territory? I love the weight to power but some of Hells Revenge in Moab just makes it chugg hard and im not sure of the best solution
Very impressive
I am interested in having my 21 250xcf done. What is the process? Di I send you the head and cylinder? Bring you the bike. I would like some more information please.
For a big bore?
Yes with the possibility of getting the get ecu as well@@HPRaceDevelopment
Does it vibrate?
Does stock vibrate?
Thats why they telling a big bore adds low down power buth sign off at high rpm its because they getting lean on that rpm range.
Afr 12.5 is normal target where they make best hp.