2017 Honda CRF250R — HonKTMaha

All of us wonder these things, right? What if you took this off that bike, and that off this bike, and mashed them all together to make a single incredible machine? Well, like a proverbial Dr . Frankenstein, that’s what we did.

We began with the stock 2017 Honda CRF250R because, to be honest, it wasn’t getting much ride time. All of us asked ourselves, “Why don’t we would like to ride that bike given the option of all the other bikes? ” The main answer is the ’17 CRF250R is precisely the same bike as the ’16, and that means it still had the Showa SFF-Air TAC fork, which usually pretty much no one liked. Plus, this is a tad on the mellow side, motor-wise.

In a moment of brilliance—or complete stupidity—we thought, “Hey! What if we poached the top bikes within the 250F Motocross Shootout to make the Honda better? ” The winning machine for the 2017 250F MX Shootout was the Yamaha YZ250F, and one of the main reasons it took the top just right the podium was because of its KYB SSS fork. Luckily for us, as well as for you, the YZ-F fork has got the same outer tube diameter since the Honda’s even though the lower tubes have different diameters (48mm on the YZ-F and 49mm on the CRF-R). Yet swapping the forks isn’t as easy as it sounds. The Honda has a 20mm axle and the Yamaha has 22mm axle, therefore the stock Honda front side wheel won’t fit in the Yamaha fork lugs. And even if it did, the brakes don’t match up since the stock Honda front disc is 260mm and the YZ’s is 270mm.

The best way around this, and the way we achieved it, is to steal not only the fork from the Yamaha, but the front steering wheel and front brake, including the cable and lever, as well. From a functionality standpoint, this might be too expensive for a lot of budgets because that’s a lot of stock Yamaha parts for a Honda proprietor to buy. Another option is find a 2012–’13 YZ250F fork because it is essentially the same as the 2017 fork, just with 20mm axle lugs that will fit the Honda’s front steering wheel. We aren’t certain what size brake rotor came on that will bike, so you would have to make sure those line up. Lastly, if somehow you found a ’14-or-newer fork, you can then call suspension shops to find out if they have any ’13 or ’12 fork lugs. Fork lugs are screwed on to the lower fork pipes but require special seals—not the do-it-yourself job.

The second-place finisher on in the ’17 250F MX Shootout was your KTM 250 SX-F and we’ve heard of some race teams putting the KTM Keihin throttle body on the CRF250R to help in the motor department. The main difference between the throttle entire body that comes on the Honda and the one that comes on the KTM may be the position and angle of the gas injector. On the CRF-R, it is on top of the throttle body pointing at a 45-ish-degree angle toward the engine. On the SX-F the injector will be on the very bottom of the accelerator body pointing straight up. The other distinction is that the inlet and outlet diameters on the KTM throttle body are slightly smaller sized. Normally we think bigger is better, but when it comes to pressure and speed, given the same volume of air, the smaller the particular diameter, the faster and more pressure the air-fuel mixture will have.

But this is where things obtained really messy. Like, “if you are not a professional mechanic, you probably don’t want to try this yourself” messy. Unlike the fork swap, the throttle body swap requires a lot of cutting and splicing of the wiring utilize because some of the sensors and plugs used by KTM and Honda are extremely different. Also, the airboot/throttle body connection is the same, but the accelerator body/cylinder connection isn’t. Since it was a temporary mod for us (Honda doesn’t want KTM parts on the bike when we give it back) we all used duct tape to make the throttle body diameter match the cylinder inlet.

For a full how-to (if you happen to be that gnarly) we’ll have a Dr . Dirt on this bike in the print out magazine that will explain the rerouting of wires, which connectors you have to replace, and all that jazz.

It's alive... IT'S ALIVE!

Once we were done playing Dr . Frankenstein, we kicked the bicycle to life and it worked! Well, sort of. It would barely idle and had rich burble that made it unrideable.

Luckily our own tester/mechanic Allan Brown was for the case and started working his magic with Honda’s PGM-FI umschlüsselung tool. It’s a CD and you also need a laptop and a special Honda connector to plug into the bike. He started by leaning out the fuel mixture, which got the particular bike to run better and contact us we were headed in the right path. After eight maps going 2 percent leaner each time, we completed on two that we liked. The particular stock map selector button let us switch between stock Map one (which is locked and not adjustable even with the computer), Map two, and Map 3. Those would work out to be about 14 and 16 percent leaner, respectively. Our own tester preferred the 14 % (slightly richer map) while the quicker and pro-level rider liked the particular 16 percent map.

Energy

We all tested at both a tighter, smooth, jumpy track (Milestone MX) and an open, fast, rough track (Glen Helen Raceway). First, we will talk about the throttle body imod and what we felt. Cutting directly to the chase, it didn’t blow us away. The fact that we had to maintain going richer told us the KTM-only throttle body was offering the bike a lot more fuel than it was used to, but how crappily it ran (at first) furthermore told us that just adding more fuel to a bike that wasn’t designed for it doesn’t make the bike automatically better. By leaning out as far as we did, we might have been in the same range as the stock accelerator body. Or, since the throttle body is completely different, the sensors could have acquired different starting points which would provide us a very different reading. A few ton of variables and factors and, in retrospect, the fact that we all got the bike to run and also it did is pretty cool.

Did it have better power than stock? Hard to say, really. With the KTM throttle body on current lean map that we were the particular happiest with, we can say this wasn’t worse than stock but it wasn’t noticeably better either. The power character was about the same, it had great throttle response (as will the stock bike) and had wide, sort of flat mid-range power rather than a ton of torque down low or power up top.

But then why do some race teams do it? They aren’t simply slapping on the part and contacting it a day. They are, or at least have the ability to, modify heads, change out pipes, and use different software and hardware (ECUs) to tune their own machines. We could only operate inside the limited boundaries of the stock software program and it would defeat the purpose of finding out just what this swap did if we also did a bunch of motor work and slap on a pipe.

Fork Swap

Hang on a sec… Before you decide to stop reading in frustration, we haven’t got to the fork yet, and we’ll be equally forthright—yes, there is a vast improvement. The KYB SSS fork immediately gave the particular Honda way more comfort up front plus, since the Honda was already a great-cornering bike, the SSS complemented the bike’s turning characteristics quite well. The particular lug offset is nearly identical on both bikes, so the front axle placement should be the same. If they were drastically different, then the bike’s handling could have gotten way out of whack. Since the SSS fork is so smooth, this felt almost too soft with all the stock settings and that the shock was overpowering the fork. This does make sense, since the fork and surprise on a bike are developed in tandem. The stock Honda Showa fork had an overall stiff personality and needs a shock to match.

Yet all isn’t great in HonKTMaha land. With the sag set at 105mm, each of our three riders felt that the bike, specifically the shock, was way too busy. The back of the bike was jumping around and not tracking straight in the rough stuff, and really wanted to step out at the end of corners with some chop in them. Later in the day, our bigger tester hopped on the bike with out setting the sag for him and found the bike taken care of much better than with the sag at 105, (it was most likely at 110–115). Another tester tried running a lot more sag and confirmed that it assisted calm the rear down.

To really test the Franken-Bike we had former pro Dorrie Boniface come ride with us with Glen Helen. Here is his take on the bike.

“I’ve ridden the stock Yamaha 2017. I haven’t ridden a stock 250 Honda for a long time. So it’s hard for me to compare, such as engine-wise, what this one is doing when compared to stock engine. As is, I felt like I want more power from mid to top. The bottom was pretty good. This wasn’t really clear when I was in the meat of the power. Coming into a corner it seemed a little rich or something. I don’t know how the particular stock bike is, but I just didn’t feel like it was really quick for a 250, like, I wasn’t flying out there compared to other 250s. Considering that I can see some other 250s making all the jumps, I feel like I was lacking and not making the jumps.

“Handling was good. The fork is super nice. That bike turns really good. I don’t know in the event that it’s the bike or when the fork really helped it, but cornering was amazing on the bike. Really comfortable. Really good feeling to the front end of the bike. Very safe. I felt like the front tire had been sticking to the ground. I really liked it. I was pretty comfortable riding Glen Helen on stock suspension. No harshness, good plushness, but not too soft for me. The front was way better than the rear. The balance was away from. I would really try to make the back better to match the front. The rear was high for me and really busy. Especially coming down the hill, it was difficult to get the bike really sticking to the floor. The rear felt really light and am had a hard time getting it to draw in. It was high and light and busy. But the front is really great, I really like it. ”

Conclusion

Nope. We didn’t make an incredible hybrid machine taking only the good things from each bike and nothing of the bad. The throttle entire body swap is not worth the amount of function and parts and headache required to even get the bike running. Yet we do see the potential there for a gnarly engine if somebody used this as a starting point then began messing with engine work, more complicated mapping, and then pipes.

As for the fork swap, we might recommend it if you could find the appropriate forks at the right price. Just know that you’ll have to do a lot of work at the track getting the rear to match the front. You’d also want to get where the fork sits in the clamps because that would affect the balance as well. We also know that Race Tech has a spring conversion kit for the Showa SFF-Air TAC fork that the majority of people have been happy with. That way anyone is not messing with the front-to-rear balance of the bike since that fork and shock are designed to work together.

The biggest lesson we were reminded of and hopefully a lot of you out there learn from this is that bikes are way more complicated than they look. Meaning, they aren’t simply a frame, engine, fork, shock, etc ., just thrown together with almost everything being interchangeable. Most, if not every, of the parts on a bike are made in unison and aren’t going to always work on other bikes. Race teams do weird, crazy swaps simply because they have the time, resources, and a very compelling reason to try out different things—they get paid to win. That being said, if you also have the time, resources, and cause, have at it!

What we took from your Yamaha YZ250F:

• Fork


• Complete front wheel including braking mechanism rotor


• Front braking mechanism assembly (caliper, cable, master cylinder, and lever)

What we took from the KTM two hundred and fifty SX-F:

• Throttle body


• Wiring harness (to be cut up for connectors)