Has anyone tried fitting the 450 air box case to the 2024 250F? I think this it what Twisted uses with their kit to get back the low end torque the new airboot seem to sacrifice.
I had a look at the Yamaha parts on the web and it looks like the 450 airboot can fit. The throttlebodies has the same part no on the 250 and 450, and the frame mount should be the same. Question is just if the throttlebody position is the same since I guess the 450 engine is bigger?
I'm thinking of buying it, but would be nice to know if it fits (needs some mods?) before buying it. Would be fun to test it with the stock ECU and see if it runs ok (will probably go for GET och Vortex later). For the -23 450 the airboot is two separater parts, but for -24 they have made an assy out of it. Guess it is the same parts anyway?
Is there dyno runs available that compares the "Twisted kit" to the stock?
Curious about this as well. Keep us posted if you try it out.
Guess it is only a matter of time before someone makes something like this for the -24. I will mail vhm and ask.
https://www.vhm.nl/en/catalog/engine-parts/filter-parts/air-intakes-air…
If the 450 air box isn't plug and play I think I will try to get a funnel made to try in the original 250F airbox. Then you could make several different lenghts to try what works best. Would be interesting to try how long / small dia you can go before it hurst high rpm tuning/power too much.
Hope someone can answer about the 450 airbox before I have to buy one myself to try :-)
Is this what you wish for?
https://www.vhm.nl/en/catalog/engine-parts/filter-parts/air-intakes-airbox-cover/ai020621/infoorder/g+c+a+nr+view
Could be. Strange that they say it fits 2021-2024. Think the -24 airbox differs from the earlier (that's what all this is about :-) ). I mailed VHM and asked and they said they would have a -24 on their dyno in a few weeks and would have a look at it.
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I thought that though they may be slightly different the tube shape would accommodate their current insert. Sounds like they don't even know yet. Sorry.
If this fits the -24 and the previous, it can't be shorter / bigger than the earlier and should solve the problem. Anything loinger/smaller will improve low rpm torque (so no need to be sorry on your end :-) ) I can rephrase my question to VHM and see if it fits. If it does it should be worth testing (although more expensive than a new -450 airbox....) Thx for the help.
The 450 boot will not fit the 250 without an adapter, the 250 engine is smaller and the boot doesn’t quite meet the throttle body.
As for the ‘23 v ‘24 air boot they differ up top and angles but the clamping diameter are the same. I’ve never had the VHM insert but I’d assume it’ll jam in the new boot.
Forgot to update this one... Since last I got the carbon fibre funnel and had it on the dyno. First we actually tried the "old" funnel from VHM and just glued it in (similar gains but 8mm longer than the new one and fits "so so", but god enough ). Recently we got new funnels made for the 2024. The bike felt stronger at low rpm as we hoped, but it actually runs better all over. Quite large gains between 6-10000 rpm. The mods we ran was acrapovic exhaust (that alone brought approx 1,5hp). The funnel gave another hp with torque gains all over (most at 6000 rpm). When tuning the camshaft timing to the exhaust and inlet the mods gave 3-4hp total. This is borderline for the stock ecu since it is still a touch lean at 6000rpm although +10 in the fuel map. Because of that we will try it with a Vortex which should make it run even better. Lets see in a few weeks when we get the ECUs.
Didn’t feel flat up top? How long were your ‘24 inserts?
The bike seem to rev out like before (or better...). Not sure exactly how long the complete inlet tract is with the funnel, but it protrudes (if that is correct english...) approx 2 cm into the airbox. Looks like this.
A 300SX was the only mod I needed to do. But I was already ordering my upgraded 200SX. YAT
Took care of the turns and feels more nimble.
What did you end up doing to the cam timing?
More overlap, so also got even less engine braking as a "side effect". The exact cam timing needed will depend not only of the inlet lenght, but also exhaust used (we ran Acrapovic). I'm pretty sure all good engine buliders go approx the same route...
Did you end up with different cams or just move the sprockets on the stock cams?
Less engine braking is always a plus. I have 450 boot/spacer and full fmf on my 24. And have been on the dyno mapping it by still using pump gas.
Sounds very similar to our setup then :-). We are running the stock cams. Just moved the sprockets. As long as you don't move the rev limiter to far this setup should be as durable as stock ( I think/ hope...). We haven't had to change anything but clutches this year.
Yeah I don't plan on moving the limiter now anyways.
Who moved them for you or did you have a fixture or something so you were able to accurately move them?
Wild to think all these “mods” came stock on a 2014 yz250F
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