Scag tiger cub running rough

[WinterDeere]

There should be a sticker on the side of the engine cowling with an actual engine model number, probably the same label containing the serial number. That's what the Brigg's experts will need to identify the spec'd RPM for that engine, as well as the throttle plate and choke options.

 

[tomplum]

So you're saying it spits / pops? On these normally one main jet is partially clogged. RPMS are considerably low. The model and type on the top of the valve cover will give you parts info, post it and I can look up the intended RPM. 3350+ anyhow.

 

[Chieftm2]

So you're saying it spits / pops? On these normally one main jet is partially clogged. RPMS are considerably low. The model and type on the top of the valve cover will give you parts info, post it and I can look up the intended RPM. 3350+ anyhow.

I would say spitting/pops is a fair way to describe it. Here it is running

 

[Chieftm2]

There should be a sticker on the side of the engine cowling with an actual engine model number, probably the same label containing the serial number. That's what the Brigg's experts will need to identify the spec'd RPM for that engine, as well as the throttle plate and choke options.

Sorry about that. Don’t mind my horrific looking toes

 

[WinterDeere]

Engine model number is 44Q77-0136-G1, it's a very common model, and in fact I think OEM on some Scag models... not that I'm any Scag expert.

Damn near every site that lists that motor claims a different max RPM, but most seem to be either 3350 or 3400 RPM maximum. If this is the OEM motor for that mower, then the shop manual should have a detailed procedure on how to set low and high idle speeds. You'll need a tachometer, but you can pick them up cheap on Amazon.

If it's not the OEM motor, then you can use the Briggs manuals. All can be found here:

Results

www.briggsandstratton.com

 

[Chieftm2]

Thanks a bunch for the info. Did you get a chance to listen to the video? Does it sound rough to you? Just wondering if that’s contributing to what seems to be a power issue. I could be wrong but I feel like this thing should have tons of power for that little 48 inch deck? I don’t know if I mentioned it but there was a new carb put on last year. This is just a back up mower for my little farm IE why I don’t want to just pay someone else to figure it out. I have never messed with carburetors before so I’m slightly shy about taking it apart but I’m willing to try. Also the rpm’s were right at 3000. I turned it up to 3400. Not sure if the 400 is going to really make a noticeable difference. Thanks again

 

[tomplum]

That pop is likely due to one of the mains being at least partially clogged. You can clean these externally much of the time in place. Remove the top plate w/ 3 screws, and carefully remove the gasket. Use a razor blade if needed. The gaskets aren't cheap and work well just by flipping and re using them. Once the mating area is clean and you're sure there are no little bits of gasket inside, a burst or two of carb spray with the straw down each main orifice will open them up. Quickly reassemble and test run. This cuts the cleaner with fuel so you don't have the cleaner soften the main rings or fuel pipe seals.

I'll also drain the bowl before this service and after running via the side bowl solenoid. If you decide the little red straw is needed to flush the bowl out, reinstall the solenoid and run it right away. Once a test run shows it's good, back on the shroud goes.

Base idle is 1300, only notes on top speed on your build is 3600 is the alternator test speed. Increasing your running speed 10% makes a nice difference.

 

[rholmes69]

One of the things I've heard is that the pulse fuel pump on these if they've been replaced with an aftermarket, it doesn't provide enough fuel. It can idle okay, sometimes it requires a choke or high throttle to get started, but once you start trying to mow and get into the power, it just seems to bog. Might want to do a flow test on the pulse fuel pump...

 

[Chieftm2]

One of the things I've heard is that the pulse fuel pump on these if they've been replaced with an aftermarket, it doesn't provide enough fuel. It can idle okay, sometimes it requires a choke or high throttle to get started, but once you start trying to mow and get into the power, it just seems to bog. Might want to do a flow test on the pulse fuel pump...

Thanks a bunch for the info! Should I just YouTube a video on how to do it or do you have an easy way in mind of checking it?

 

[Chieftm2]

One of the things I've heard is that the pulse fuel pump on these if they've been replaced with an aftermarket, it doesn't provide enough fuel. It can idle okay, sometimes it requires a choke or high throttle to get started, but once you start trying to mow and get into the power, it just seems to bog. Might want to do a flow test on the pulse fuel pump...

I disconnected at the carb and cranked it and it’s pushing plenty of fuel. That pulse line is in rough shape though, not a great seal at the bottom? Thoughts?