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2024/10/24 15:12:02

Brent

Rato 740 / Predator 670 Governor or Carburetor Problem?

Hello,
I have a new Rato 740 (Predator 670 equivalent) with 10 hours on it. It was surging occasionally so I decided to remove the carburetor to clean it. When I put the carb back on I noticed the governor doesn't allow the throttle to return to the idle position (with engine off) unless I push it the rest of the way with my finger.

Any idea why this would happen? Am I missing a spring or something that pulls the governor back? Does the carb throttle spring not have enough tension to close itself? FWIW I dipped the carb in Chem-Dip for about 25 minutes.

I've attached a picture for reference. You can see the throttle is at maybe 40% or so and just stays there unless I "help" it go back all the way.

Thank you for your time and help!

- Brent

4 comments Leave a comment

SRTsFZ6

Is this on a generator or what kind of machine/ use?

If a generator or a machine that always runs at 3,600RPMs (no throttle),
when the engine is off, the govener holds the throttle wide open.

You should be able to push the throttle back to the closed position.

Please post what the engine operates..

FYI:

https://www.manualslib.com/manual/3116333/Rato-R740.html

.

2024/10/24 18:12:09

Brent

Scott,
The engine is on a mini skid loader. It doesn't have a tach but based on the sound, and my (little) experience it seemed to run ~3600 WOT and maybe 1200-1400 idle.

Thank you for that manual!! It shows how to adjust the governor, and confirms the Throttle Arm should be in contact with the Throttle Stop Screw. I'll get some replacement gaskets, make the governor adjustment and report back with my findings.

Thanks again,
Brent

2024/10/25 06:36:16

Brent

Hi Scott,
Back again! Haven't been using the machine for a while so I put off fixing it.

I gave up on the old carburetor and put a new OEM one on. The first thing I noticed is that it would not idle, going from WOT to idle the engine would shut down. I adjusted the idle screws until that stopped but now the engine surges pretty bad at WOT. I sprayed starter fluid around all the gasket areas to see of there might be a leak but didn't have any results. All gaskets are new btw.

The only way to keep it running WOT without a constant surge is with the choke closed a bit. Should I try putting a fuel pump on it? Admittedly I didn't check the main jet sizes before installing because I assumed they are the correct size...but if it's not getting enough fuel then maybe I need to drill them out or something?

Thanks,
Brent

2024/12/23 19:22:58

SRTsFZ6

So will the idle come down (and stay) when operated by the throttle?
With the adjustable throttle, it should come down and when at full throttle, most engines run
at 3,600. If not re-adjust the governor..

Before modifying a brand new OEM carb, can you run a gravity feed tank and line to the carb?

That or pop off the fuel line from the carb, start the engine and see if your getting the fuel volume needed (put the hose into a container to observe and not spray everywhere).

It does sound as if it's leaning out, carb running dry would also do that.
Check any in-line fuel filters and fuel line itself, that it's not cogged internally
(or breaking down internally from e- fuel).

.

2024/12/24 13:17:56

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Rato 740 / Predator 670 Governor or Carburetor Problem?

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