We recently published a youtube video about a ktm 112 supermini build.  Our title hints at these bikes being the fastest on the track, and I wanted to go into detail on why a supermini is arguably the most potent weapon in racing!  Let's do a back story and then some neat math to see if this is true.

In 2017, hp race development powered Ty Masterpool to 2 supermini championships aboard a TM 100.  It was a true 100cc's of size and on our dyno it produces just under 30 hp in race trim.  At that time, the KTM was it's previous generation engine with an archaic 105 cylinder that was at least 20 years old in development.  A lynks 112 in that year made about 27-28 hp in full race trim on our dyno.  A really good Pro Circuit kx109 would tickle about 27.5 that year, and the best 150r we ever built about 10 years ago was 25.

In 2017 our unobtanium 85cc mod package (sold a very few of these) used a custom modified pipe, huge amounts of R&D, and could knock down similar numbers as those aforementioned supermini builds.  But the larger engines did have some power width advantages.  To get our KTM supermini package dialed, we generally stuck at 105cc, our cylinder had huge amounts of epoxy within the transfer ports to reshape and redesign the ports more modern like our good 85's), we had a specially welded and reshaped exhaust port, and a special redesigned head sealing surface with orings moved to the head, the inner oring groove filled in on the cylinder, and a the cylinder beefed up to prevent the base nut tabs from cracking off which occurred often at good power levels.  A really good super ktm could knock down about 31 in this trim - and was truly amazing for what is started at (out of the box, about 21-22hp on a 105 of that era for us).  The cost of doing this was huge and i'll never do another one again!

Now - while it's not easy, eclipsing that power mark requires far less effort, as ktm has really done a fantastic job on the new cylinder 

Back to 2017 - Ty raced on the same exact track on back to back motos as 250A/Pro class, there was no track work between, and that year was the year of Justin Cooper.  If you go look, Ty aboard his supermini was able to turn his fastest lap about 1 second a lap off cooper's fastest lap on his Yamaha 250f.   On identical tracks, back to back.

It was a spectacle to see - and I truly feel no one has ever turned any size motorcycle better than Ty did that year - he was little at the time and fit that size bike perfectly. 

So let's talk basic power to weight numbers!  
A KTM 112 is approximately 160 lbs in race trim. Let's factor in a supermini rider at 120 lbs (ty was 105!) and you have a combined weight of 280 and a power output at the time of 29.5 for a power to weight of 9.49 lbs per HP

A Yamaha 250f of the time in race trim was about 233 lbs, and a rider would be around 140lbs
Combined weight 377, on our dyno a Yamaha of that era in cooper race trim was about 41 hp (yeah yeah sure, 50hp - nope....we dyno'd some bikes of a Texas pro on that same build)

That's a power to weight of 9.2lbs/hp. 

The edge here goes to the 250f, however you also need to factor in the additional rotational inertia of the 250 wheels - which basically evens them out.  Now - that said, the 250f has MUCH wider power which allows it to have a higher avg power output at all times...

However with the right rider (Ty) on the right track (loretta's) we got to witness a supermini get really really close to the next prodigy's best lap time.  Pretty cool, I'd say!


What about at 33 hp? 
Well, now the super gets the edge with 8.48 lbs per HP.   If you paid attention in physics - F=MA and when you have a low M, and a big F, your acceleration A is the best!  
If you saw our 2022 factory edition KTM250f video, you'd see we  have managed to squeek out 46 now with our ECU, and VP racing fuels Pro6

I weigh 165 - bike weighs, in race trim, 230 ish - for a power to weight of 8.58 lbs per HP.
I can tell you this - I don't think I'd want to drag race our supermini build on my 250!!!!  Maybe that's a video for another day...

We will have a longer video on this bike on the dyno with some pipe testing and mapping changes, but for now, we figured it be neat to post up a little insight in to the building of a 70 hp ktm 450.

The key to power on these is the head - and while we don't show exact details about the final port, this is the process we undergo to get there.  The stock 450 is about 53 hp as delivered off the showroom, with a pipe and an ECU we usually see 55.  To take it up to 70 is a huge gain - one that we are really proud of on our dyno.  This is coupled to our custom tuned GET ecu, race fuel, and a megaphone pipe.  With a conventional exhaust, this package is good for about 66 hp. 

With the 2023 models just around the corner and the 22.5 models basically here, I've decided to publish a mini pipe shootout. 

To be fair to each product - we tested on the same bike, same day, and did tons of pulls to make sure all data was repeatable.  The purpose of this test isn't to showcase one product over another, or to say one works better than another - but rather to really point out that stock pipe to aftermarket pipe tests without a proper tune up are a very POOR test. 

What most people experience in feel when changing a pipe - is what the pipe does to mapping.  Much like what the smartphone tuning apps do to bike feel - a pipe will alter all areas of the mapping similarly in their own unique way.  This is where track feel and feedback are as important as dyno feedback.  We all want the fastest bike, and most power - but getting good track feel is important too.

Check out our test - I shot a ton of video that didn't make it through edit - but check back for a track test of a few of these options soon!

Since 2016 HP has offered an in house 270 kit for the KTM group of bikes.  It's a strong performer and outshines the other kit on the market by a good bit.  We briefly stopped selling our kit when the big manufacturer kit hit the market because of their tremendous advantage in pricing, but after testing back to back, I decided to start making the kits again due to our large performance advantage.  It's my opinion people don't just want a bike that IS 270cc, but a bike that RUNS like it's 270cc.   We've attached a short youtube of everything you need to know about the base level 270 kit.  It's available in our store and is in our opinion the single best budget mod you can do for a 250 ktm, gas gas or husky.

Our Kit uses a custom designed, CP made piston, with a DLC coated pin, anti friction skirt coating, low tension oil ring and optimized, lightened shape that minimizes any excess material.  We have 2 versions, but are mostly selling the 15:1 piston, which CAN run on pump gas.  This kit works best with a properly tuned EC, which can be clearly seen in our youtube video.  If you own a bike 21 and newer bike, you can NOT reflash the OEM ecu.  We are working towards ideas around this - but for now an aftermarket CDI or fuel piggy back controller is needed.  These bikes flat out RIP and are about as much fun as you can have on 2 wheels.  You can couple our custom ground camshafts and valve springs for even more power. 
I've also attached a chart from a different bike and test (using stp correction rather than what we publish now days of SAE which "reads lower") of a perfectly tuned 270 kit from the other offering on the market that had a vortex ecu and dyno tuning vs our kit with same ecu and different tunign to match ours.  The difference was quite large in this case - but in other testing we usually see a 2 hp difference.  It's a little bit baffling - as we really like all the parts of the other kit, but it just hasn't performed as well for us.

Let's take a short dive into the showa 49mm spring fork.  This fork is found on honda, kawasaki models.  It's a very good fork from a design perspsective - basically the same as a kyb SSS.

Some questions we hope to answer for people in a future article is the ACTUAL damping difference between this showa 49mm fork and say a KYB "SSS".  NO guessing and "feeling" and actual real world facts.  What we hope people who care to improve their knowledge and riding results will learn - is that most of the time - what you FEEL is the chassis feedback.  Often times you can not get rid of certain feelings via a damping change. 

Check back soon for a DEEP dive inside showa and KYB forks

While I never publish the majority of our testing efforts, with youtube and my goals to add some truth in media and some real data vs whatever we wish to call the lack of data that is currently NOT published in "testing" reviews - I recently did a 4 head shootout on a Husky TC85 specifically for youtube (in reality we've done 20 different heads when developing), and this test will apply to all KTM 85 and Gas Gas 85 bikes as well.  But the over arching goal here is not to make you buy a specific head but rather make all of us smarter through more education and testing. 
Everyone is "convinced" that higher compression is always better. 
Everyone is "convinced" that x pipe or y pipe is better. 
Everyone is "convinced" some massive secrets in R&D exists that allow 1 engine builder to be head and shoulders better than the rest. 
But if we take a step back - and think logically for a minute - we should ask some simple questions.  If all ktm had to do was raise their compression to sell a more powerful bike - why wouldn't they?  If some shop has a magical head design - and sells it - why doesn't ktm just buy it, and copy it?  If porting is as simple as raise a few ports, make them bigger - and go faster - then surely KTM can hire a guy to do that, right?  The reality is that engine power gains are hard to come by, hard to find, and extremely nuanced.  They require lots of testing, in multiple manners to get an idea of what you really did.  Two strokes in particular are very special engines.  They work as a system that needs to be in harmony - not as one item you can improve at a time.

I've attached our youtube video for you to check out, of note - the lowest compression, smallest narrowest squish banded head made the most power, and the tightest squish, highest compression head made the least power.

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So let's talk two stroke head science for a second.  Two stroke heads do a list of things.  Firstly - via their volume they set  the compression ratio.  If you do some basic reading on the modern otto cycle, you can learn a lot about the theoretical differences in compression ratio.  In doing so, you might realize that past a certain compression ratio the power gains become very very small even in a perfect world where fuel capability doesn't matter. 

Two stroke heads also influence combustion speed.  They do so by using a squish band that forces all the compressed gaseous mixture towards the spark plug and into a small tiny space, the chamber.  This is a huge advantage a two stroke carries over modern four strokes - as four stroke heads have most of their area taken up by valves and cant have large squish band/area (referred to as quench in a 4 stroke - yeah both worlds didn't work together often).  As an example to how big of a difference this can make, a 2 stroke typically requires 8-12 degrees peak ignition advance at peak torque (moment of highest cyl pressure).  A four stroke in the mx world (state of the art for NA 4t tech) typically requires 30-33 degrees ignition advance at peak torque.  Because the four stroke has less mixture turbulence and speed, it has a harder time lighting it off and getting it to combust as rapidly and as such it requires more spark advance.  It's not that the 4 strokes WANTS to have to use 30+ degrees of spark advance, but it has to due to the chamber shape.  The Nascar world with 2 valves, and a much larger quench (squish) area than the 4 valve mx head world uses much less timing, in the mid 20's currently.  While the 2 less valves ultimately can't produce the power per CC the 4 valve heads can, they do produce as much torque per CC - potentially with better efficiency due to the better spark and quench.

Two stroke heads also use design considerations to help cool the piston dome, via the squish action.  

Two stroke head designs influence the scavenging of the engine.  Scavenging is what 2 stroke builders call the interaction of the outgoing exhaust flow with the incoming intake charge.  This flow uses a loop type motion that comes out of the transfers, up the cylinder back side and into the head and around, then down the exhaust side in a loop type shape.  The head shape - has  a large effect on this loop.  Imagine a totally flat head spaced up from the piston for the volume we want, vs a perfectly semi circular shape, or hemi shape.  The hemi shape SHOULD help that loop flow shape more than a flat head.  Now add in the dynamic of a squish band, size, shape, angle, and then combustion chamber shape, and things get complicated!  Remember we want to get ALL of the spent charge out, and sharp tight corners or dead space in the loop that doesn't flow - can leave old spend charge still in the engine - not desirable.

Two stroke heads, with careful placement of the spark plug, can influence burn speed even more.  I wont detail more of this - but imagine a combustion chamber that is really deep, plug far away from piston, then a chamber where the plug is closer to the piston - but we equalize the volumes...  Which one would burn faster?
Clever designs of heads have used the coolant water to do helpful things for power.  I wont detail this either, but you can find as much as 1 hp via some modern water routing techniques on engines that are pushing the detonation limits.

And last but MOST importantly - the head design influences the EGT.  A 2 stroke relies on the exhaust system to provide the majority of air movement and thusly POWER.  In fact, a 2 stroke is not truly NA - the pipe is actually like a super charger or turbo charger.  Pipes vary their functional dimension based off their average gas temperature inside.  It's really complicated - but a hotter pipe works at higher rpm better, and cooler exact same pipe will work at lower rpm better relative to one another.  AKA hotter the pipe gets, the higher the rpm it works at.  
When we design a head, if it happens to lower egt into a range the pipe isn't designed for - we will loose power.  Same applies for a head that increases EGT. 
Ultimately - heads are not as simple as just go for more compression or less! They have an influence on every aspect inside the engine, and finding the perfect match for the engine combo is what yields best results. 

I routinely see claims from various head companies that I know to be false because we have tested them.  Sure, tighten up that squish for "better faster combustion with less detonation".  That's the blanket "theory" statement you learn about two stroke heads that was written 50 years ago.  And, in theory, it should be correct.  But then why is it that, when I tighten the squish on a stock yz250 - I usually have to add spark advance to get the power back to where it was?  Shouldn't I need to retard the ignition?
What happens if you tighten the squish, open the bowl and equalize the compression ratio to before the changes, but in doing so lower the pipe temperature, or alter the scavenging flow such that now the engine produces less power?  Or shifts the power in a direction you didn't want?  These are the things that actually happen, rather than theoretically happen.  My goal is to get you thinking.  The more you think, the better decisions you can make when you buy a product.

Well, we finally got our hands on a new 2022 yz125 for some initial baseline dyno runs. The owner of the bike also has a previous generation yz134 we built for him which has become his favorite bike in the stable of 250f's, 350f, and 450f.  The owner is in his 60's and loves to ride with his sons - and has found the little bore 125 based machines to be the most fun and safest to keep riding year around.  

His comments on the 2022 yz were that it could use a little more bottom and pulling  power out of corners, but he felt the top end and over rev was fantastic.  He also stated both he and his sons felt the changed ergonomics made the bike handle much better than the previous year bike - I'd bet the stiffer suspension settings for 2022 helped in that role a bit (as the older model is quite soft by modern standards)

Lets get to the video - if you haven't seen it, it's attached below.
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 Now, Let's move on to some dyno charts.  We did a huge amount of testing - most of which isn't shown in the video.  But we found the bike is jetted a little rich most specifically on the pilot and needle.  The main jet is actually close for pump gas - but has room to go leaner for more power with race fuels.

The stock jetting we had on our USA spec bike was
75 pilot
160 main
2nd clip on stock needle NYDF

While I think there is more time we will spend on the jetting - we tested from 65-75 and found that it developed a lean bog around the 68 needle unless we had the air screw at 1/2 turn from all the way in.  

I've seen reports online of people going to more "normal pwk" settings with a 50-55 pilot and 175 ish main.  But we repeatable lost power going richer on the main - and found the low end running quality deteriorated dramatically below a 65 pilot.  Jets add to each other, meaning if you went to a 50 pilot and a 175 main - it wouldn't be as rich as a 75 and 175 - the pilot wont contribute as much fuel at a 50.   Something to keep in mind is the is a powerjet carb - which adds fuel to the main jet circuit.  If the powerjet were plugged, the main would need to go to around a 185-190 to run right.  I highly suggest you keep the powerjet system - it improves midrange power without hurting over rev.

One of the best mods we have found for the KTM 85 platform, whether it's an 85 or  a 105 or 112 supermini, is a bored and modified carburetor.   This mod is also effective on all other brands - from kx85 to yz85 and rm85, as well as gas gas 85 and husky 85.  Check out our video of the mod process, as well as the dyno charts of what results we got.  To be fair, this was all stock vs bored and jetted right, a stock carb jetted a little differently would have been closer but we typically see nice gains in the 1hp range.

Let's take a look at just how much power a stock KTM 85, husky 85, and gas gas 85 really makes.  I've tested almost 20 fresh or new stock bikes in the past year, and they are all really similar (as they should be).   Some are better than others, and in this instance we have decided to publish about the best case scenario we see on a new stock 85. 

Check out our youtube if you haven't and see below for more charts!

Below is a chart of 4 back to back dyno pulls.  As you can see there is a power variation between a few.  This is why dyno testing procedures must be understood - and consistent for repeatable testing results.  What you will see is that in the case of the current stock 85, it really likes to have some pipe temperature and power improves when hot.  On many stock bikes, power gets worse with temp, or shifts to the right with less bottom and mid and more top/over rev. 

I've got a little bit of extra information for you as well. Below is the result we got when swapping to an FMF fatty from the stock pipe
As you can see, we got a small but measurable and repeatable improvement in power.  I've seen upwards of 2 hp sometimes from stock to aftermarket on these bikes, but not on this one.  We will publish a complete pipe showdown shortly so check back soon!

What does the KTM 350 actually make on the dyno?  Let's check it out!
If you haven't seen our youtube video please watch!  
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And if you did, well here are some charts for your viewing pleasure. So of note - even though a 450 makes it's power much earlier in the rpm range, the average power over the rpm range of a gear change isn't much better between the  350 and 450. Additionally - the extra RPM range of the 350 allows it to be geared shorter/tighter.  This tighter gearing plays a huge role in fast a bike accelerates.  

While the 350 isn't for everyone - it makes plenty of power to be able to compete heads up vs a 450 in our opinion.
We will publish vs some other 450's soon!

First up is map 1 vs map 2. Quite a big difference on the 350.  

Next up is our GET ECU and tune up vs Map1 OEM.  We made nice gains vs both map 1 and 2, with the added ability to have custom maps for fuels, pipes, and mods.  

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