Briggs twin hunts??

[RideRed 0]

Hey guys need help once more. So I've been foolin with this GT-1600. It has the opposed twin briggs, early style with an adjustable main jet. It was running really poorly with air bubbles in the fuel line. So I rebuilt the carb and replaced all the lines and filter. Now it will start much easier and will idle as pretty as you could ask, BUT at wide open throttle she hunts real bad or just dies if you open her up too fast.

Any thoughts on this? Is the gov out of wack? Am I missing something? Short of pulling that pain in the butt and installing a kolher what can I do to fix it quick? My grass is waking up and I need to mow soon! Thanks!

[rickv1957 75]

Carb may be set a little lean ?,Rick

[markslawnmowerworld 4]

I work in a lawnmower shop six days a week all year long..and have seen this problem with opposed briggs engines.....there is a product in a can form. called sea-foam......put this directly in your gas tank and let it work its magic through to the carburetor...if this does not help you must re-clean the carburetor jets with tiny probes.......the sea foam is available at auto parts stores. :omg:

[Roger from southern Iowa 1]

My advice.....Take Marks advice!

Sea Foam is great, almost too good to be real. :omg:

[RideRed 0]

OK, so I readjusted the carb. found the sweet spot in the idle circuit then made it a tad rich about an eighth of a turn. slow idle is perfect. BUT, I still have to open the throttle very very slow or it dies. Once I get it at WOT it hunts BAD... I tried everything on the main jet screw with little to no change. If I close it all the way the thing dies (which it should), but from barely open to almost removed the so-called adjustable main jet has little effect. Also played with different governor spring locations. It would change how fast or slow it would hunt, but none of the hole positions stopped it. It just seams like it's starving for fuel . Could the float be set too low??

I'll get some sea foam today (I use it in my truck, and I like it too), but I have a hard time thinking that fuel additive will help. I did a complete rebuild yesterday on the carb...I mean the full monty. briggs factory kit with all new gaskets, springs, adjusting screws, o-ring...everything. And blasted out the whole body with carb cleaner and whipped out all the sludge, polished all the gasket surfaces...

I guess I could have missed something. It's easy enough to take it back off a check again. I'm just wondering if there is something on these models that would mimick a clogged carb??

[stevasaurus 23,281]

Just a thought...check the point gap. Timing could be off.

[RideRed 0]

Just a thought...check the point gap. Timing could be off.

I would if it had any...this thing has the Magnetron electronic ignition which the manual says requires no adjustments.

Anyway, I've pulled the carb back off and apart. I'm cleaning it again by running a tiny wire in all the ports and jets and blowing everything out with shop air. Seafoam has been added to the tank and engine oil has been changed (did you know this stupid thing has no filter ). We'll see what happens...

[TT-(Moderator) 1,162]

did you know this stupid thing has no filter

That's alright...... it doesn't have an oil pump either.

Are you using a good inline filter and have you checked the strainer screen on the fuel shut-off valve?

[RideRed 0]

Alrighty then...

I have spent over an hour poking at all the little holes and spraying it with carb cleaner then blowing it out. Put it back on, played with the screws and like magic it runs like a champ now . I guess the little wire knocked something loose. Did'nt feel anything give and the wire did'nt come out dirty but it worked and I'm not questioning it. The main jet screw actually does something now...

Now the only issue is huge amount of smoke when I change throttle position, but I can live with that. Afterall it is 25 years old??

Thanks guys for making me go back and check. I don't see this ragged old briggs lasting much longer (hopefully this season). So I'll look into another powerplant for the future. Any thoughts on a strait bolt-on swapable kohler for this model??

:D

[RideRed 0]

Just for visual gradification

[RideRed 0]

:omg:

I'm gonna shoot it!!!

After all that it was running fine. I lubed up the deck and drove it around for a test mow. Once it got really really hot it started running funny again. Stopped to readjust the carb, and I turned both screws in until they seated and it was still running?? As if it was running super rich, it ran with no effect of either screw and smoked, it started to hunt at slow idle when the screw was all the way in but did'nt die.

IF a 25 year old motor still has the original muffler on it, and that muffler is rusty and clogged will it make the engine run rich? I'm gonna pull my hair out on this thing! I just had it...

Why would it run perfect when cold and warmed up but take a dump when really hot (after 15 min of run time)? What is going on?? :D

[Duff 206]

Whatever you do, don't shoot the tractor. I don't have a clue what the engine's major malfunction is all about, but the rest of the machine appears in the pictures to be in primo shape - worth a heart transplant if needed!

JMHO.....

Duff :omg:

[Roger from southern Iowa 1]

I suspect contamination in the carb........AGAIN

I would completely flush the fuel system, clean the carb one more time and install a fresh paper inline fuel filter between the tank and fuel pump/ carb.

Just my opinion...

[markslawnmowerworld 4]

Sorry to see you are having troubles with your engine....

if i remember correctly that engine at top r.p.ms is 3600. if you messed with the governor or the governor springs, it could be over-running the rpms.

this means its a possablity that the magnitron solid state coil has been overheated...and is in a failure-state....when the coil gets to hot the engine shuts down.....this i have seen happen on these engines...

the only way to test this coil in this state is to hook-up two spark testers at the same time, and wait to see the failure in action...and the brightness of the spark testers will be very low in this state for a bad coil. :omg:

[RideRed 0]

You guys are never gonna believe this one...

So it was running like it was super rich, I just knew the carb was loading up, but why? Well, I got mad and said "to heck with this" and clamped off the fuel line while it was running. It ran on for another 2 minutes and then cleared up and started to run good then ran out of fuel and started to die. So I removed the clamp and it ran on then loaded up again, so I clamped it again. Did this about three times.

Alright, it's running rich to the point of flooding. I thought the float may have a slow leak and was sinking, so I pulled off the top of the carb. Took out the float and shook it...nothing inside and light as a feather (no leak).

Next I'm thinking the float height is wrong. So I bend the tang put it back in. Now I have the top of the bowl in my hand and I'm moving it up and down to make sure the needle seats properly. I notice if I push it down it will seat, but if I let it fall it will not. As I'm watching it I see the new needle clip pop. So I tweek it alittle to keep it from dragging...it got worse.

I take it apart again and feel around with my finger nail to see what's up. Low and behold there is a tiny casting mark sticking out just enough to reach out and grab the clip and stop the needle. <_<

So long story longer, I break out the mini files and smooth out the carb body. I just put it back on and what do you know, back to running like it should (for now).

Never seen anything like it...I'll let her sit overnight and see what she runs like tomorrow! :D

[RideRed 0]

So far so good...

modified the muffler alittle this morning, it was rusted out anyway. runs good now. did some test mowing and noticed a weird pattern in the grass. took off the deck and flipped it over, one of the blades is bent and all of them look like they've been breaking rocks.

oh well, this is the fun stuff that comes with a new machine. fine tuning something someone else thought was junk and turning it into the nicest tractor in town is the best part. after they're cleaned up and running right I get bored.

anyway, here's the finial run down of what I figure happened (maybe this will help someone else someday).

-got the tractor and it ran but had an ever changing idle and was LOUD.

-rebuilt the carb (1st time), did not get the main jet pasage clear. this caused it to idle nice but hunt at WOT.

-broke down carb again (2nd time), cleared main jet but put float needle clip in different 2nd time around. this caused the float to hang and flood the bowl.

-changed the oil with strait 30. previous oil must have been 10w30 because the oil change made the motor run much more quiet.

-pulled down the carb again (3rd time), found casting flaw and fixed needle problem. must have been the trick, cause she runs great now.

-modified muffler. this leaned her out a bit (as it should) and got rid of a very annoying rattle.

now if I pick up a set of blades tomorrow she'll be ready to join the fleet.

in order of purchase; C-160 w/hydro, 310-8, 604, GT-1600

Thanks for all the help guys!!