Briggs 17.5 OHV Throttle/RPM

[Ezpz]

Fixed up a craftsman tractor over the winter with a 17.5 briggs engine (31c707 0230 e1) I've always had trouble getting this thing to run smoothly. It was running pretty well yesterday then I put the shroud and air filter on today and it wants to surge again The rpm will fluctuate a little bit and I'll get some random popping sounds. Can anyone tell me if the governor arm should be all the way to its stopping point while running with the throttle lever at max? The governor arm will reach its furthest point using the throttle lever while the engine is off, but while running it does not make it this far. Pushing the arm with my finger will rev it up, none of the linkages are binding. I've done the following already:

New head & gasket, valves lapped, new plug, seafoam/oil change
new carburetor(s), set throttle cable on its bracket, new air filters, fresh gas
even tightened up governor spring a tiny bit

Starting to wonder if i can get my hands on a carb with high speed adjustments for this motor or something similar. Also, bending the tang for the governor spring doesn't increase top speed right? The arm has a hard stop so I assumed putting more tension on it just gets me to top speed sooner

 

[Boobala]

Surging ( rpm running up and down) is USUALLY caused by a carburetor issue .. did you clean out the fuel-tank and replace ALL the fuel lines, fuel-filter, AND shut-off valve, they're NOT immune to specks of dirt, it just go's into a carb , NEW or not. messing with the governor is something I avoid, unless I'm readjusting it because I removed it and then only following the manual,
try to re-clean the carb AND fuel system, adjust the governor with steps in the Manual, here's a link for it.......

https://docs.google.com/file/d/0B6NaqjIxWV1ybEN0LWo3azl6OUU/edit

You may want to re-set the valves as a side step, this humorous video is put out by a VERY-SMART Tech watch to the end !

https://www.youtube.com/watch?v=8PEUt_KAcYk&t=21s

 

[Ezpz]

Thanks for the links! I flushed the lines and changed the fuel filter, added fresh gas and connected a new carb right out of the box! I'm going to run it with the air filter off and see what happens, I was very pleased with the way it was running 2 short days ago. Just a little confused as to how the governor should behave on this engine under ideal conditions. Hell even the throttle lever is confusing on this tractor, as far as i know idle is very bottom, "fast" is the notch in the middle, and the top half of the throttle is all choke adjustment. I blame craftsman for the ****** illustration on that panel. Set the valves about a week ago but will look again soon, glad i put a little rtv under the valve cover

 

[Ezpz]

I should mention that even with the air filter connected it started running better with the idle mixture screw almost completely turned out

 

[Boobala]

Sounds like you still have a carb problem with the idle speed screw setting BUT it also sounds like your combo-choke /throttle cable needs adjusting, ... loosen (slightly) the locking screw on the throttle/choke cable, (cable attached to white plastic slider, see pic ) now push throttle lever on dash fwd to CHOKE position, use your finger on the carb linkage to push linkage until choke plate at RED circle is fully closed ( easier done with air cleaner removed as in pic) tighten the lock screw, at the same time, now pull throttle back to the DETENT, ( full throttle setting,) choke SHOULD be open and throttle linkage at full movement, pull throttle all the way back ( turtle) you may have to fiddle with cable at the lockscrew a bit to get it just right, CHECK cable is in correct position with dash lever positions, ( CHOKE, DETENT ( FULL THROTTLE) AND IDLE NOW see if it will idle, you may have to adjust that idle speed screw, ... POST your results, I have, and many other members have that exact carb. ( Nikki 1 Bbl. )

..... click on pic to enlarge

 

[Ezpz]

Before starting the engine for the first time this year (about a week ago) I set the throttle cable like you described using the craftsman manual, here is a shot of my throttle lever set in the notch in the middle. Other pics are of the linkages at choke and what the craftsman manual calls "fast" (middle notch in throttle slider.) Had to mow today as its going to rain all week, engine surged and popped the whole time so frustrating, ive tried 3 different carburetors and its all the same.

 

[Boobala]

Looking at YOUR pics it appears the choke/governor SPRING is "BROKEN" or not connected the Lonnnng spring on the throttle linkage rod to the governor control arm, .. check out pics of MY carb .........

........

could be your problem.......... keep us posted ...

 

[Ezpz]

the spring that rides the throttle linkage is actually intact and taut, cant really see it in the photos lol. Out of desperation I've taken about 200 rpm off my govenor spring and it actually sounded really good for about a half an hour.. until i engaged the blades

 

[Ezpz]

I feel like this engine just wants more guzzoline

 

[Boobala]

the spring that rides the throttle linkage is actually intact and taut, cant really see it in the photos lol. Out of desperation I've taken about 200 rpm off my govenor spring and it actually sounded really good for about a half an hour.. until i engaged the blades

OK, what about the governor spring BEHIND the throttle control bracket .... ???

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