Briggs & Stratton OHV 500E series surge and or flutter

[Tired not retired]

Hello all. This is the first time I have joined any forum. Looks very interesting. I am a 40 yr mechanic and yet I am just about bald from scratching my head on this Briggs OHV 500E series engine. It is a model 9P602-0076-F1. Has a pretty good surge. Prime it 2 or 3 times and start right up. Cleaned Fuel tank and made sure screen in tank was clean, replaced fuel line, disassembled carb. completely, inspected and cleaned, changed oil making sure it was at correct level, replaced o-ring on intake pipe at cyl. head. Runs the same. Ordered a new carb. and installed. Seem to help the surge a little but it is still there. It does run great and starts easy but there has to be something causing that annoying surge. I wondered if maybe valve adjustment may be the problem. Looked on line for valve clearance and found 3 or 4 different answers. I looked at Briggs chart and does not show 9P600 under OHV single cyl.. This is the first 500E series for me so is there any common characteristics known on this particular engine? Would anyone else like to scratch their head on this one? Thanks for any advice.:confused2:

 

[primerbulb120]

I've had a couple of these that still surged with a 100% clean carburetor. I use a micro drill bit to very slightly enlarge the main jet. They run perfect after that.

Harbor Freight sells a cheap set of micro drill bits. They like to snap off inside the jet because they're so brittle, so I always drill the jet with the drill in reverse. It still drills, but the bit doesn't bite in and break.

 

[tom3]

Run into this with these ultra lean carbs sometimes. I use a set of tip cleaners and a mich or caliper to fit and measure the stock jet, go maybe 10 or 20% bigger - whatever drill bit I have that's close. If you go too far the old carb jet can be reused. I have a couple older Tecumseh motors with adj. carbs that do this running a bit rich, lean out to get it smooth and it won't pick up with load, just live with the surging.

 

[mechanic mark]

https://www.briggsandstratton.com/e...ualSearch.html?searchrequested=09p602-0076-f1

thanks ILENGINE

 

[Tired not retired]

I've had a couple of these that still surged with a 100% clean carburetor. I use a micro drill bit to very slightly enlarge the main jet. They run perfect after that.

Harbor Freight sells a cheap set of micro drill bits. They like to snap off inside the jet because they're so brittle, so I always drill the jet with the drill in reverse. It still drills, but the bit doesn't bite in and break.

I thought about that but figured I would reach out first. I have the old carb. that I cleaned before installing the new carb. . Both run the same so I will experiment with the old carb..

 

[Tired not retired]

please recheck your numbers, nothing coming up

Those are the correct numbers.

 

[ILENGINE]

.004-.008 clearance on both valves. Mechanic Mark did you put the 0 in front of the 9 since the parts lookup system needs 6 digits to operate correctly. Are we sure that is is a fuel/carb related issue and not something goofy with the governor system.

 

[Tired not retired]

.004-.008 clearance on both valves. Mechanic Mark did you put the 0 in front of the 9 since the parts lookup system needs 6 digits to operate correctly. Are we sure that is is a fuel/carb related issue and not something goofy with the governor system.

Thanks for those valve specs. . Carb. has a baffle over throat but I can put one finger over one side of baffle and another over the other side and restrict air flow enough to smooth it right out. Im going to experiment with the old carb jet as soon as I can get back to it again.I will let you all know how that goes. Thanks everyone for the input.

 

[Tired not retired]

I've had a couple of these that still surged with a 100% clean carburetor. I use a micro drill bit to very slightly enlarge the main jet. They run perfect after that.

Harbor Freight sells a cheap set of micro drill bits. They like to snap off inside the jet because they're so brittle, so I always drill the jet with the drill in reverse. It still drills, but the bit doesn't bite in and break.

OK, I got a chance to get back to this 500E series. I used my smallest tip cleaner and enlarged the jet just slightly on the old carb.. RUNS PERFECT! Thanks for the input everyone.

 

[Tired not retired]

OK, I got a chance to get back to this 500E series. I used my smallest tip cleaner and enlarged the jet just slightly on the old carb.. RUNS PERFECT! Thanks for the input everyone.

Had another 500E series today with a surge worse than last one. Cleaned carb. and did the same thing to the jet on this one. Runs like a new one.