5.5 GPM Machine for Sale

For sale is a Honda GX390 with an Udor 5.5 GPM (gear drive) pump, set up for tank bypass (Zeromatic unloader).

I purchased it as a 4 GPM direct drive in 2014 and installed the 5.5 GPM gear drive in 2015.

The engine has 125 hours on it, and the pump has less than 75.

This pump has been stored in a heated garage since I upgraded to 8 GPM last year. I used it last November for approximately 2 hours, but it hasn’t seen any use since then.

Asking $1200.00 or best offer.

Local pick-up only. (Asheville, NC)

Please PM me for more info.

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Would you sell just the pump?

No, sorry.

Dammit man. Where was this 3 weeks ago?!? What is the PSI output with the gx390 driving it?

I’m not sure what the max pressure is, but I only used it for softwashing, so I never checked the max pressure. I know there’s a thread on here somewhere with the formula though.

Solid buy and price. Wish you had it listed 3 weeks ago. I just got a 5.5 @2500 pressurepro

Thanks!
(Isn’t that the way it usually goes though, LOL!)

Bump

Best (reasonable) offer takes it.

Bump!

Interested if you want to ship :slight_smile:

Just PM’d you

@Atlas1, just curious about the process for upgrading pumps on the GX390… Do you buy the 5.5 gpm pump WITH the gear drive already installed on it?

Or do you buy a direct drive pump and put a gear reduction box on? I’ve been looking online at them and I mostly see pumps without gear drives, and I sometimes see the gear reduction boxes themselves.

If you put a gear reduction box between a GX390 and a direct drive pump, will it then draw water from a buffer tank, or does the pump have to be specifically designed as a gear driven pump? I’m just not sure because physically the direct drive pumps and the gear drive pumps all look the same to me, mines the shaft housing on the direct drive and the gear box on the gear driven pumps. Both look like direct bolt-on attachments to a generic triplex pump.

I saw that IBS was suggesting this pump. Looks nice. I’m just trying to understand if the pump has to come with the gear reduction or if they can be purchased separately.

Any experience or knowledge shared would be greatly appreciated!

PS…Does anyone know what happens if you put a gear reduction box on a 4gpm/4000 psi pump?

Here’s a thread I made where i documented my upgrade to a gear driven pump… should have everything you need in it. I got mine from Russ Johnson.

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I got mine from Paul at The Power Wash Store. My gear drive Udor was 875 (or so) shipped in 2015

Thanks. I’ve read that thread and you bought your pump with the gear box on it I believe. I guess what I’m trying to figure out is if your pump that came with the gear box on it is any different than a direct drive pump with a standalone gear reduction box bolted to it. I haven’t found any threads where someone had a pump already and just added the gear box, or if that is even a possibility.

I’m wondering mostly for curiosity’s sake, but also for pulling from a buffer tank. I don’t have a buffer tank. So it’s not like this is critical for me lol. I just want to know if there is physically something different about the actual PUMP itself that allows it to pull water with or if its strictly because of the lower RPM that the gear reduction box allows for the causes it to pull water, versus a direct drive pump rotating at 3600 RPM. Is the only reason a direct drive can’t effectively pull water is because of it’s high RPM, or is the pump mechanically different in some way?

Yes, the internal geometry is different. Gpm is a function of pump speed, and cylinder displacement (bore x stroke). The high speed pumps have smaller plungers, so slowing them down reduces your output. The lower speed (belt or gear driven) pumps have larger plungers, which is what gives them suction/lift

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Thanks Alex.

Close-Up-Presure-Washer-Crank-Pump-Head

So in this diagram, for a direct drive pump, the plungers and the cylinder bore are much smaller, not allowing any suction and requiring the water to be forced in (either gravity assist or direct garden hose hookup)?

For this same diagram, if it were a belt drive or gear driven pump, the plungers and bore are larger, resulting in lower pressure, higher volume and also sucking or pulling in water, even against gravity?

Just want to make sure I have it right. I also thought this triplex plunger pump animation was helpful a bit too, at least to understand the mechanics of what’s happening. Visual learning is best for me lol.

https://gfycat.com/gifs/detail/dearestwaterloggedanemone

**Photo is not mine. Found it online with the notes already made on it.

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