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 Popping through carb 
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Post Popping through carb
I have a 31hp Briggs longtail popping through carb,did compression test 122/125 but leak down test 80 .Going to pull heads is there anything that anyone would suggest for an upgrade or what to look for (push rods,rockers,etc,etc)The motor has 240 hours on it and 9 years old.Have only run non-ethanol 90 octane fuel.Oil changed ever 30 hours with Mobil 1.Any suggestions would be super great.


Tue May 01, 2018 6:42 pm
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Post Re: Popping through carb
Sounds like your headed the right direction. Watch the rockers while rolling over to verify cam is good. Have you checked to make sure valves are not to tight? Other than that it sounds like you have well seasoned heads. Once this valvejob is done valves will seal for a very long time


Tue May 01, 2018 7:00 pm
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Post Re: Popping through carb
Valve clearance.006. No clatter at startup,or while running.


Tue May 01, 2018 7:19 pm
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Post Re: Popping through carb
Will, would an intake leak cause the popping too?

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Tue May 01, 2018 8:15 pm
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Post Re: Popping through carb
Yes, it could, but unless it was fairly recently disassembled and put back together, intake leak (while possible) isn't likely. Odds are greater it's valve related.

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Tue May 01, 2018 8:34 pm
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Post Re: Popping through carb
Yes Russ is right. It's possible to have a lean cough but the leakdown test is showing different. 80% leakdown is kinda off the charts. I know leakdown test results vary a lot. You might even have a piece of carbon etc stuck under valve


Wed May 02, 2018 7:29 am
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Post Re: Popping through carb
I bet most of that leaking is from the Intake valve... Causing lots of reversion and choking itself/lean popping through the carb.

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Wed May 02, 2018 9:22 am
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Post Re: Popping through carb
Well that sounds where I’m going, I only have the front cover off. I have other projects going right now,going to get hard and heavy tomorrow or Friday. I will post updates as I go along.
And Guys Thanks for the information very helpful.


Wed May 02, 2018 11:10 pm
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Post Re: Popping through carb
MaXXis85 you were right 2 bent intake valves,next question who out there sells a better intake valve that might be more durable?I’m not interested in in high performance just a little more durable also a better push rod,really aluminum push rods.Any information would be greatly appreciated.Thanks again.


Mon May 07, 2018 11:10 pm
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Post Re: Popping through carb
The stock pushrods are fine, but you can go with some heavy duty ones. Maxxis, will C, boat Dr, backwater performance, performance vtwins are all options to purchase them. The one piece stainless valves from manley are considered a must-do for those that want an upgraded valve. Again, those listed above are sources.

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Tue May 08, 2018 5:34 am
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Post Re: Popping through carb
did you check the valves for runout? Or you just see daylight around the seats? if the valves are straight you can do a valve job and be good again. I can also install stainless valves and properly cut you seats, and perform a 3 angle valve job that uses all of your seat area and will seal way better than briggs did.

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Tue May 08, 2018 1:18 pm
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Post Re: Popping through carb
MaXXis85 Thank You for all great knowledge and help. I have called Briggs and they are the stupidest people on this earth. I have been on the phone for almost two hours.The last call they transferred me to was a distributor in California and I don’t think that she could tie her own shoes.In no way she was going to help me even after I was told by Briggs engineers on what to do.If you have a factory defect with your motor your screwed.Sorry for venting.It’s a shame that a company like Briggs will hire people that don’t have a clue what a Briggs engine is or what it does.MaXXis85 I have a machine shop just 2.7 miles from me,and he has all the arbors for small engines.Again Thank You.


Wed May 09, 2018 11:30 am
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Post Re: Popping through carb
Got heads back from machine shop,intake was never seated from factory.Waiting for gaskets and seals hope to have running by this weekend.Again Thanks.


Mon May 14, 2018 9:35 pm
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Post Re: Popping through carb
GDLT31 wrote:
Got heads back from machine shop,intake was never seated from factory.Waiting for gaskets and seals hope to have running by this weekend.Again Thanks.

They were seated... The seats moved after the heads seen heat cycles. Every briggs will go through this some worse than others.

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Tue May 15, 2018 8:53 am
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Post Re: Popping through carb
He said intake, so maybe he wasn't talking intake valves?

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Tue May 15, 2018 11:11 am
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Post Re: Popping through carb
a couple posts up he was talking about "bent intake valves"

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Tue May 15, 2018 12:33 pm
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Post Re: Popping through carb
You're just arguing to argue now. Lol

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Tue May 15, 2018 1:16 pm
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Post Re: Popping through carb
I’m sorry if I don’t get my point across as well as other people.When I was in Vietnam from 68 to 71 I was not quick enough to jump out of the way 3 bullets on different occasions. The one that did the most damage is one that took a small portion of the back of head off. That is why I have trouble getting my message across.I hope you forgive me for my disability.I just want to thank members of MMT for helping me to keep my mud motor running.

Thank You,


Tue May 15, 2018 11:36 pm
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Post Re: Popping through carb
You're good, dude. I'm just harassing maxxis.

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Wed May 16, 2018 4:35 am
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Post Re: Popping through carb
Russ is an asshole. LOL

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Wed May 16, 2018 7:56 am
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Post Re: Popping through carb
Yep.

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Wed May 16, 2018 9:45 am
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