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Crazy Power from New 15.5 and 16 ktm 250f

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Well - off a previous thread, the pipe choice thread, I had posted some info on what we had tested with the fmf system on the new 15.5 and 16 ktm 250f's.

After our initial round of testing - which Im ashamed to say we had the bike for almost 4 months to finalize it all, Im quite pleased with the end result.

 

I've attached two charts, first is broken in, all stock ktm250f on the race oil we run vs our new mod combo. 

 

The second is vs wheel speed so you can sort of get an apples to apples, of the mod run in 3rd gear (we have a heavy dyno drum - 3rd gear run time on ours is similar to most dyno jet in 5th gear) vs a 3rd gear run on relatively stock 08 honda 450 that has a pipe and jetting (which has a nicer curve than new honda 450's...why i choose for this comparison)

Of course the 450 has more low end - but the little 250f isn't far off!  Shows just why these 250f's are so fast in pro racing.

 

I pity whoever has to line up against these bad boys - my best full blown yz250f that has had big success this past year at various races can't hold a candle to the mod, and cost a pretty penny do build.  The ktm doesn't need upgraded valves, springs, crank, or piston to get the results...much cheaper end result.  Kudos to KTM this year - last years mod bike isn't even close either.

CRF450vsKTM16Mod.png

 

16ktmModvs Stock.png

Edited by harrperf
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Well - off a previous thread, the pipe choice thread, I had posted some info on what we had tested with the fmf system on the new 15.5 and 16 ktm 250f's.

After our initial round of testing - which Im ashamed to say we had the bike for almost 4 months to finalize it all, Im quite pleased with the end result.

I've attached two charts, first is broken in, all stock ktm250f on the race oil we run vs our new mod combo.

The second is vs wheel speed so you can sort of get an apples to apples, of the mod run in 3rd gear (we have a heavy dyno drum - 3rd gear run time on ours is similar to most dyno jet in 5th gear) vs a 3rd gear run on relatively stock 08 honda 450 that has a pipe and jetting (which has a nicer curve than new honda 450's...why i choose for this comparison)

Of course the 450 has more low end - but the little 250f isn't far off! Shows just why these 250f's are so fast in pro racing.

I pity whoever has to line up against these bad boys - my best full blown yz250f that has had big success this past year at various races can't hold a candle to the mod, and cost a pretty penny do build. The ktm doesn't need upgraded valves, springs, crank, or piston to get the results...much cheaper end result. Kudos to KTM this year - last years mod bike isn't even close either.

CRF450vsKTM16Mod.png

16ktmModvs Stock.png

So pretty much this new Ktm blows the yz250f away?

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The 08 crf 450 is considered the best 450 engine they ever made ?

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So pretty much this new Ktm blows the yz250f away?

On the dyno there is no comparison.

On the track the yz feels competitive.

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that looks very impressive . how do you think reliability will be? i want one of these bikes , but a little worried , being a first year 

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that looks very impressive . how do you think reliability will be? i want one of these bikes , but a little worried , being a first year

Power doesnt hurt pieces... Rpm does.

And our cams profiles are less aggressive than last year which were dead reliable.

The rest of the pieces are stock, crank, piston, valves and springs.

It should be as reliable as stock which has been fairly solid for most people. As new as this engine is its not much different than last years model in the pieces used.

Only "issue" we have heard about locally was a kid who lost some transmissions on his 15.5 fes. Ktm totally warrentied with 16 engines... So time will tell if thats better but they claim it is solved

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Power doesnt hurt pieces... Rpm does.

Seems to be a difficult thang to grasp

Calculate the force at tdc of a

85 piston at 13k

Vs

500 piston at 6k

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Seems to be a difficult thang to grasp

Calculate the force at tdc of a

85 piston at 13k

Vs

500 piston at 6k

85 using 47mm stroke has a mean piston speed of 20m/sec

500 has a mean piston speed of about 15m/sec

Mean piston speed is a good general guide to any size engine, as materials and design process progresses higher and higher sustained mean piston speeds are possible.

What you need to wrap your head around is on a given engine, in the case of this 250f (or any engine) that increases in power do hardly anything to crank load.

Usually the weak link is valve train, both in rpm and oil film strength to prevent lobe smearing.

If you get really i depth to gas forces and inertial forces, you will learn that the gas forces barely even accelerate the piston downward. The just minimize the losses incurred by the crank having to accelerate the piston downward netting in positive work for the entire cycle.

While 500s rev more than 6k for some riders... The fact their mean piston speed is so slow is a great reason they last so long vs strung out 85s... Despite making tremendously more power.

Even more amazing is their crank pin and main bearings arent all that much bigger on a 500.. But again inertial loads are everything. A tiny 85 at 17k would have higher actual forces on crank parts than a 500 at 6k if my napkin brain storming is correct.

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It's amazing you can get that much power from a 250 and it be reliable ,4 years ago this was the kind of power a full factory effort would struggle to achieve ,and then it would have a lifespan of a 65 piston, ktm have pushed the boundaries of what we thought was possible ,I've heard with mapping etc the 350 produces more peak power than last year's 450

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It is amazing.

Whats really crazy is the motors 10 years ago look very similar.

The knowledge in resonance and cams has expanded (cams now arent just more aggressive.. rather better matched to port and resonance)

And lastly behind the scenes the oems are cutting frictional losses... Windage, trans drag being too close to cases, oil passageways... Etc.

It all adds up

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What kind of mods were used to make this power? This is crazy

This bike has had a lot. The better question is what isnt done.

However it will be used for supercross so all avenues for reliability were persued with some treatments to transmission and engine parts that helps.

To make the power requires the right head porting, cam combo, mapping, and pipe combo to match, as well as some piston to head clearance changes. Luckily the ktm has the highest quality crank, valves and valve springs money can buy...and the piston works well.

I think last years piston is of higher quality but the compression bump on the new one done in the areas it was done adds power

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