Biggest pump to match with a honda gx390?

Whats the biggest GPM pump we can pair with a honda gx390? Have a machine we picked up in the middle of the season last year and the CAT pump already went down twice so going to switch it out to something else. Would like to switch over to another belt driven machine, however this is fairly new machine and would rather not have it sitting around broken

What do you mean by biggest? Highest GPM or Highest PSI?

GPM sorry. should have specified that

423 gpm us about as big as you can go


You could wash a house fast with that!

5.5gpm 2500 psi would be ideal for most house washing, 4gpm@4000 psi for everything else?

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house washing world record at 423 gpm

Better get a buffer tank first tho…


just use a lake


If you are just washing houses I would go 7 gpm at about 2000.

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got it. we havent had good luck with suction the last year with our direct drive pumps, we are going to trying a bigger buffer tank raised up a bit and starting them on half throttle as recommended on the forum. Any input?

Yep. Don’t do it. Raised tanks are wreck hazards. Belt drive a 7 gpm off you engine.

convert to belt drive?

yep. Put a pulley on it and be done with direct drive

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gonna have to look into how its done!

Its easier to do a direct to gear driven set up, and gear will still pull water

I called a local place asking about having this done, they said it would take 3 days of labor to add it to a belt drive skid. Am I missing something here?

any link to how its done?


True. I just like beltdrive. This may be easier for the poster though