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Well, I try to be buddies with everyone, but I can't say I've ever met the gent.
I put one on my 23 300sx. I’ve only ridden it once since I installed it But it definitely is more snappy and revs quicker. Cost Me $50 for the pump and $8 for a piece of hose. I wired it to come on whenever the engine is running. It’s one speed (full speed). It does take a little while longer for it to warm up but so far so good. I removed all the guts for the stock water pump as well. If you’re even a little mechanically inclined you could instal one yourself. I still need to 3d print a bracket but it’s held in pretty good with just the hoses.
Good point about removing the mechanical water pump internals. I assume you mean just the impeller?.
I’d guess the pro teams would also remove the drive gear and shaft to further reduce drag on the crank. That’d require putting a solid seal or Welch plug in to blank off the shaft orifice.
So on a KTM it’s actually really easy to remove the mechanical Water pump. The crank driven gear That spins the water pump shaft is plastic and slides right off the shaft. For ease of converting back and not having to get a block off seal made or weld up the hole in the case I simply took the plastic gear off the input side of the shaft and took the impeller off the output side of the shaft and drilled and wire tied the shaft on both sides of the seal so it can’t move side to side. So it basically just sits there keeping the oil and the water separate. On a jap bike it would be necessary to remove the shaft completely and put a block off seal in.
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Bumping old thread instead of starting a new one.
It seems this trend fell off, but I got thinking about it during Saturday's mudder. Would electric water pumps have helped? One of the benefits is that you can run them at full speed regardless of engine speed. Theoretically, this should help keep bikes running cooler on those days where the engine is varying rpm dramatically with a lot of clutch modulation...like a mud race. Granted, there's a little more risk of another part breaking. But could we see these return for mud races someday?
Who says they dont?
Fallen off? How so?
All the high and mid-level 250 teams are using them, minus the Austrian machines (which have never used them).
From my count wandering the pits, more 250 bikes have them then when I created this thread.
Def hasnt fallen off at all. If anything its just become nearly ubiquitous and not really newsworthy anymore.
So that leaves the question why have not the Austrian teams use them?
They cannot afford the parts or overtime to build them.
They dont use special coatings on their forks either. Look at chase or ap’s lower fork tubes and theyre regular chrome. They seem to do things their own way.
Likely the same reason it took them so long to enter the 2nd injector conversation.
And no sir Pop, you are incorrect. Their special coating is just clear/chrome. It is in fact different from a bare showa or kyb stanchion.
I've asked two different engine builders (Twisted and XPR), they both said that the electric water pump gains are extremely negligible on the KTM engines due to their water pump design. In standard form, they have the least amount of drag and power loss to operate of any 250 engine.
Correct, and some of their forks for have a flat-looking bronze lower coating, like Stewart's forks. A lot more had that coating early last season, but it's reverted back to mostly clear chrome.
Oh ok cool, do you know what the chrome colored coating theyre using is called?
Cool thank you that makes perfect sense👍
to elaborate on that a bit... The austrian waterpumps run on a plain bushing type bearing and a simple seal, rather than a mechanical seal in the others. Which, is minimal in drag to begin with, hence the lackluster return on investment from the boys with the answers - Jamie or Chad.
That's interesting. I would have thought pushing the water itself would require the vast majority of the power the pump takes from the motor - not overcoming the resistance/drag of the seal.
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RE: fork stiction, Ping has a good interview with Paul Thede (Race Tech) on a recent Whiskey Throttle. He did extensive testing on reducing stiction. Summary, coatings don’t do much. Bit listen to interview for much more detail.
The real gain is being able to run the pump at its most efficient rpm (propellers, impeller, pumps all work poorly outside of the optimal rpm.) At overrev, the regular water pump cavitates and has flow issues. The electric just keeps right on spinning at the perfect rpm. It allows for more radical tuning. That's right, spinning the water pump faster actually causes problems.
No kidding? Did not know that. Whaddya know!
That is an awesome bit of tech I had not thought of. Thanks!
The main benefit is not horse power savings its being able to run the water through the radiator at the flow rate you want to maximize the cooling efficiency. If the water goes through the radiator to fast it will not cool as well same goes if the water flows to slow.
Hmm. Thanks everyone--I guess I hadn't heard of them for a few years and figured they disappeared. Must not have been looking hard enough in pit bits.
But if they were on all the bikes at Foxboro then I guess the cooling gains weren't enough to overcome the mud.
"Coolant flow too fast" is a popular myth. We had a cooling systems engineer from the local Caterpillar engine facility talk to our thermodynamics class. He debunked that popular misconception. Probably the thing I remember most from that class.
Here's a good vid that talks about it briefly. Flow rate discussion starts around 7:55
https://youtu.be/Ldfuzy_JJUo?si=s-ktSROPOovg3z0w
The available Bud racing and xpr kits appear to plug into the diagnostic port on the Honda from what I can see. Which would be running the fan at a fixed speed. I have been using the diagnostic port to power a radiator fan and a headlight when needed. Read the wiring diagram and figured which pins were hot and ground. I like this option because there is no risk of running the battery dead. Accessory items will only run when the bike is on.
There’s a motocross action post on their site that has some info saying the Honda takes a lot more effort to spin the pump than say a ktm group bike. The gains on them just may be negligible at that point.
Late reply holy shit im useless. You bump start button and pump turns on, to turn it off hold kill switch button for a couple extra seconds.
We got one on the newer model yz250f just purchased and its a TD one but unsure how that one is wired in.
I’m still trying to figure out how to get the TD or XPR electric pump for the ‘25 YZ250f. It isn’t listed on either of their sites.
The only one I seem to be able to find is the Bud Racing version with some hideous white hoses…
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