Small gas-powered water pumps

bamatoolmaker · May 1, 2007

I cant recall any negatives about anything linked to the Honda name

Skyco · Aug 9, 2007

Does anyone know what the inlet/outlet thread is on the little Subaru-Robin PKV101 pump?
I picked one up today for a song compared to the list price, but it was missing the adapters to go from the threaded input/outputs to a hose. It is close to 1" pipe thread but not quite the same...
I did find the overpriced suction hose at Northern Tool is a perfect fit but I'd like to make other adapters.

_RaT_ · Aug 10, 2007

Skyco said:
Does anyone know what the inlet/outlet thread is on the little Subaru-Robin PKV101 pump?
I picked one up today for a song compared to the list price, but it was missing the adapters to go from the threaded input/outputs to a hose. It is close to 1" pipe thread but not quite the same...
I did find the overpriced suction hose at Northern Tool is a perfect fit but I'd like to make other adapters.

It might be 1" NST (national straight thread) which is a hose thread. 1" ips fittings will not work. Quality suction hose is costly, it is the most critical part of pumping efficiency after the pump of course.

Skyco · Aug 10, 2007

I think you are right about the straight pipe thread...I think it may also be referred to as industrial pipe thread. Now I just have to find where to buy some fittings for it. Northern Tool had a very limited selection and they seemed to fit poorly. The female on their suction hose fit well. I did spring for their suction hose, even though it seemed kinda high

The drought in the NC mountains has severly curtailed my water supply...our spring fed pond has greatly diminished in size. The spring has basically dried up since we are 13" short so far this year on rainfall. The pond has shrunk tremendously which is too bad because the local wildlife get much of their drinking water from the pond and the huge frog population is stressed I imagine. Back in the early spring we had plenty of water, to the point the pond was overflowing, now it is down about 6 ft!
My plan is to place one of those 500-1000 gallon tanks on a hill and fill it with the spring water using the gas pump when we get water again. We don't drink the water when we boondock/camp on the property but it is nice clear clean water usefull for washing. Might even be good to drink, I need to get it tested. Don't have electrical power on the 10 acres either so I was delighted to find a deal on the pump on closeout at Harbor Freight and I had a 15% off coupon too so it came to $150.
Fired it up last night for a test and was pleased with how quiet it is

I'm a die hard Honda small engine fan but the Robin Subaru engines appear to be very nicely made, have a big 9 horse one on my log splitter also...

California · Aug 10, 2007

Skyco said:
... straight pipe thread... have to find where to buy some fittings for it.

Threaded electrical conduit fittings might be useful to make an adapter. This is similar to pipe thread, but without the taper.

_RaT_ · Aug 10, 2007

California said:
Threaded electrical conduit fittings might be useful to make an adapter. This is similar to pipe thread, but without the taper.

I'm pretty sure the pitch on the 1" hose thread is different then ips threads and the straight threads found on electrical conduit.

kdfisher · Mar 8, 2012

Hoping this thread is not too ancient for a reply

I'm pretty much set on the small Honda wx 10 for reasons mentioned here, but unsure of it's potential on my small property which I plan to use for garden irrigation. The specs call for suction at 26 feet and head at 119 feet with 36 gal min thrown in.

Water will be pumped/drawn from a creek that sits about 35 feet below a planned cistern. Pumping distance about 80 feet. I don't need alot of water but would like some guesstimate as to how much output to expect. I'm sure throttle setting has an effect. But will it successfully fill a 350 gallon tank in say an hour?

Reason for confusion relates to loss of flow/diminished output at different head heights.

Thanks for that throttle suggestion. Sure wish the little sucker had a remote kill switch. It's not easy climbing that wooded rocky hill. An electric source is out of the question because of distance.

Thanks guys. Hoping your season is a successful one.

xtn · Mar 8, 2012

kdfisher said:
The specs call for suction at 26 feet and head at 119 feet with 36 gal min thrown in.

Water will be pumped/drawn from a creek that sits about 35 feet below a planned cistern. Pumping distance about 80 feet. I don't need alot of water but would like some guesstimate as to how much output to expect. I'm sure throttle setting has an effect. But will it successfully fill a 350 gallon tank in say an hour?

I'm not one hundred percent sure on this, but it seems to me that the relationship of flow to head ought to be a linear one if we exclude frictional losses. So if you've got 36 gpm at 0 ft head, and presumably 0 gpm at 110 ft head, you ought to get about 24 gpm at 35 ft head. Of course that's straight up. The longer your hose is due to further horizontal travel, the more friction losses will reduce that number, but any reasonably distance shouldn't make significant difference.

So 24 gpm will fill up a 350 gal tank in about 15 minutes.

xtn

California · Mar 8, 2012

kdfisher said:
... Honda wx 10 ...

Water will be pumped/drawn from a creek that sits about 35 feet below a planned cistern. Pumping distance about 80 feet. ... will it successfully fill a 350 gallon tank in say an hour?

I Googled on 'honda wx10 pump curve'. Here's the lift/volume graph for that pump.
Honda Water Pumps WX10, WB20, WB30

The chart indicates at 35 ft lift, expect 35 gpm. Output hose friction will reduce this slightly so xn's 24 gpm sounds just right in real-world operation.

I use a similar pump to power my backpack gold dredge. 1.5" blue collapsible discharge hose works fine for output with minimal friction. There is an iron pipe to PVC pipe plastic adapter that is just right to fit the inside id of blue hose, and attach it to the garden-hose pump output.

The important consideration for pumping is to get the pump right down at water level. Suction lift, and air leaks on the input side, kill output much more than lift on the output side of the pump. As for the remote kill - maybe string doorbell wire alongside the hose?