BriggsandStratton 675Exi engine - black smoke after carberutor rebuilding

[purisahil41]

Hi folks,

I bought a yard machine lawnmower (BriggsAndStratton 675 exi - https://www.briggsandstratton.com/n...nes/push-mower-engines/exi-engine-series.html) last Fall (9 months old). I did not use the fuel completely last year and left some of it in the gas tank.
This year the lawnmower failed to start up, I followed steps as per online video to clean the carberutor and assembled it again yesterday

The lawnmower started normally after assembling but it started dripping gasoline, I realized (an hour later) that I left the "float valve needle" (https://shop.briggsandstratton.com/products/briggs-and-stratton-696136-float-needle-valve) out and did not connect it while reassembling.
I re-assembled the carberutor and set the float valve needle as required and started this morning and I don't see any gas leakage anymore and the lawn mower starts up in the first crank.

However, it is giving a lot of black smoke from the exhaust (I only ran it for 5 mins) and also a lot of vibration. I'm try to think if I should take it to a repair center or it might be extra gasonline that made it's way into the engine when I assembled incorrectly yesterday without the float valve needle.

Thoughts?

 

[Rivets]

Two things to check before taking it to the shop. First, check to see if the choke is fully open, may just need adjusting. Second, I would take another look at the float level, may be set to rich.

 

[purisahil41]

Two things to check before taking it to the shop. First, check to see if the choke is fully open, may just need adjusting. Second, I would take another look at the float level, may be set to rich.

Thanks for the response!
In this engine, I believe that the choke is automatically adjusted, any steps how to see if it's fully open? While reassembling I made sure that all linkages were moving freely over the carberutor.

Also how do I take a look or modify the float level?
I used this video on how to setup the float -

This is the same engine as my lawnmower

 

[Rivets]

Sorry, I didn’t look up which carb you had. The carb in the video shows no primer, if your carb has no primer, then it should have a choke butterfly. Check to see if you assembled the auto choke release on the correct side of the choke control, so that it opens the choke, not closes. I’ll be gone for the rest of the day, but if you need more help I’m sure others will chime in. Otherwise I’ll be back late tonight or tomorrow.

 

[purisahil41]

Sorry, I didn’t look up which carb you had. The carb in the video shows no primer, if your carb has no primer, then it should have a choke butterfly. Check to see if you assembled the auto choke release on the correct side of the choke control, so that it opens the choke, not closes. I’ll be gone for the rest of the day, but if you need more help I’m sure others will chime in. Otherwise I’ll be back late tonight or tomorrow.

Thanks a lot @Rivets!
" Check to see if you assembled the auto choke release on the correct side of the choke control, so that it opens the choke, not closes."
I just validated that the linkages/springs are in the exact same as

. How can I verify or double check this - "assembled the auto choke release on the correct side of the choke control, so that it opens the choke, not closes"

 

[purisahil41]

Also forgot to mention, the lawnmower is running fine otherwise, I don't lose power when it starts/ it doesnt die after starting/ always starts on the first crank.
Wondering if this would be because I missed the float valve needle earlier which would have added more fuel and if I run it for sometime it should correct itself (after that extra fuel burns)

 

[cpurvis]

Better check the oil level, too. If it sat for an hour without any needle valve in it, that gas had to go somewhere.

 

[DunDikke]

How is the airfilter. Does it run better without the filter?

 

[Rivets]

First, the guy in the video should check his carb assembly again. I’ll bet that the carb was taken off and when it was reinstalled it was tipped slightly CCW allowing the choke arm to contact the mounting plate. Would just have to twist it slightly and solve the problem. Back to you problem. With your engine running and smoking, air cleaner filter and cover off, look to see if the choke butterfly is open as seen in video. If it is open, choke is working properly. We then have to look to an internal problem in the carb. When you cleaned the carb, did you remove the white jet assembly to clean it? If so how did you clean it?

 

[purisahil41]

I checked the air filter too, it appeared fine (considering the mower has been used only 4 or 5 times) before.

@Rivets - ". When you cleaned the carb, did you remove the white jet assembly to clean it? If so how did you clean it?" - Yes I took out the jet assembly and cleaned it up with a small wire to make sure the holes were not clogged.
This morning I left the lawnmower running for 5 mins, after which the black smoke decreased considerably.
I'll be using it over the weekend and hopefully it was just the earlier overloaded gasoline that was producing it, but I'll update this thread either way.
Thanks a lot for your help guys!