Hey all,
I’ve just started my first jetter trailer build and I’m going to using a Kawasaki engine FD series 31
Im planning on using the Udor 34/25 which says it’s rated at 9GPM and 3625 psi with a gearbox.
there’s a number of companies out there with this same setup but they’re getting 4000 psi at 10 GPM.
Can anyone point me in the right direction of the aftermarket gears or modifications I’ll need to bump this up to those number?
Greatly appreciated
That is a 1450 RPM pump. If you use the common 2.2:1 reduction ratio (via gear or belt drive), your engine would need to spin at around 3,190 RPM (1450 × 2.2) to produce the pumps rated gpm. Since the majority of small engines are designed to run most efficiently at 3600 RPM. That extra 400 RPM slightly overspins the pump, which can increase the gpm output.
In theory, this could bring your output closer to 10 GPM, compared to the rated 9 GPM. A lot of guys on here run 5.5 GPM pumps but get over 6 gpm because of this.
I do not recommend you exceed the pump’s rated pressure. With enough horsepower, in theory you could, but you don’t want to push the pump beyond its designed pressure limits for the sale of longevity and safety.
so do you recommend setting a governor so the engine doesn’t go above 3,200 RPMs?
No, small engines should be running at 3,600 rpm. Running it at lower rpms for long hours will most likely overheat it since it’s air cooled. From a cost standpoint I would much rather overspin a pump and shorten its life vs damaging an engine.
The other option would be to use a 1750 rpm pump which would be closer in line with 3600 rpm. Could potentially extend the life of the pump as well since it’s not being spun at its max (3,800 rpm) just might not get its rated gpm/psi.
That’s just what the napkin math says, in reality it’s close enough that either option will run fine for long enough to make money and replace when needed.
OK, understood. So basically its ideal to find a pump rated for 1750 RPM with a standard 2.2 gear box but if you got a 1450 RPM pump don’t do anything to your engine but realize you may have a slightly shortened pump life and a slightly higher GPM output.
Correct
but not a canpump 
Why risk shortening the pump’s lifespan even further by choosing a low-quality option?
just curious, how did you determine the quality of the chinese canpump vs udor or GP or some other brand like that? Is it just one of those things like “not worth the risk, maybe its as good but impossible to know” or is there something in particular about their pumps that you don’t like? China is a tech powerhouse, I assume they have the capability to produce pumps that far exceed whatever Italy could produce if they wanted to.
The difference comes down to materials, construction, and quality control.
Canpump uses a ceramic-coated piston over a metal core, likely stainless steel. Over time, the coating can chip or crack exposing the metal to corrosion and scoring. It will also wear down over time with extended use under heat and pressure. For occasional homeowner use, this is fine, but under daily commercial operation, these pistons typically last hundreds of hours rather than thousands.
Udor, by contrast, uses a solid-core ceramic piston, roughly seven times harder than stainless steel, resistant to corrosion, and stable under heat and pressure. These pistons can run for thousands of hours with minimal wear, maintaining seal integrity thanks to smooth surfaces and tighter tolerances.
Quality control is another major factor. Every Udor pump is factory-tested and built to ISO-9001 certification, this ensures consistent production to industry standards. Canpump lists manufacturing features on their site but doesn’t provide the same clear documentation of rigorous testing or build standards.
While China can produce advanced technology like semiconductors or EV components, that doesn’t automatically translate to precision mechanical manufacturing or consistent quality control. Italian manufacturers like Udor have decades of experience, tighter machining tolerances, and strict quality processes maintained batch after batch. Many companies using Chinese pump makers prioritize lowering costs over consistency.
As I mentioned in the other thread, I’ve personally handled a Canpump units. It felt lighter, rougher, and less refined. Even if improvements have been made in recent years, for a small price difference, choosing a proven name like Udor makes far more sense for serious, continuous use.
Its good to know there is a definitive reason not to buy a canpump pump over an udor even if you will save a few hundred dollars. I don’t want to save the amount I’d make off 1 single house wash but end up with a pump that’s going to take a nosedive way earlier and then end up costing me way more money in lost revenue. Best to get Honda 690 and Udor 30/24 8GPM/3500PSI with udor gearbox.
Sorry for the derail, but damn that’s some good information Ohio, never seen somebody actually explain what the problem with Canpump is other than “its Chinese”.
