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I have a JD LT166 that I just put a new carb from eBay (China) on. It starts up easily and runs but is blowing black smoke and 'sputters'. It stays running and even idles, just rough. Adjusting the one screw on the top doesn't have any effect. My altitude is around 5500'. I believe it is running too rich. I would like to rejet it, but don't have any idea what/where to get jets for it. Any help would be appreciated.

I have tried 2 eBay carbs with the same result.

Set the float level to a LOWER setting and test for power and proper running. So instead of the float being level with the carb bowl mounting flange, make it to where the fuel will shut off sooner. Float rides lower into the carb bowl when it shuts off the fuel flow.

OR get a high altitude main jet IF your carb has one available.

Take the air filter off and check that the choke is fully open with the throttle control in the run position.

Thanks for the replies.

slomo said:

Set the float level to a LOWER setting and test for power and proper running. So instead of the float being level with the carb bowl mounting flange, make it to where the fuel will shut off sooner. Float rides lower into the carb bowl when it shuts off the fuel flow.

OR get a high altitude main jet IF your carb has one available.

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Maybe I'm being dense here, but I don't understand how setting the float lower will let the carb run leaner by allowing more airflow while into the mixture. Also, I was hoping someone would have an idea of where to get jets for these carbs.

bertsmobile1 said:

Take the air filter off and check that the choke is fully open with the throttle control in the run position.

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I am running it without the air filter installed right now. I figured that the less air restriction right now would be best. All controls are set correctly and working as far as I can see.

I'm pretty sure it's just running to rich because of altitude.

Lower float levels can make the engine run leaner. At 5500', you need a high altitude main jet. An HA jet has a SMALLER orfice than the regular or sea level main jet you already have. Your engine has code numbers to it. Look yours up specifically the carb. Look for a high altitude main jet for your carb. The higher the altitude the less fuel you need for a proper A/F ratio. There is less air at your house than most other folks.

Removing the air filter is for TESTING ONLY.

Stop buying ebay Chinese carbs. Put the OEM carb back on. Get a high altitude main jet for it. Clean/flush out your fuel tank and install ALL new hoses from tank to carb. Blow out tank with compressed air.

Briggs 806634 (JD PN M144916). No guarantee it will fit the aftermarket carb.

Thanks for replies foiks.

StarTech said:

Briggs 806634 (JD PN M144916). No guarantee it will fit the aftermarket carb.

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Thanks for the part number. Unfortunately, I am using an after market (eBay-China) carb right now. I still have the original carb and I'm sure it has that in it since it used to run fine.

slomo said:

Lower float levels can make the engine run leaner. At 5500', you need a high altitude main jet. An HA jet has a SMALLER orfice than the regular or sea level main jet you already have. Your engine has code numbers to it. Look yours up specifically the carb. Look for a high altitude main jet for your carb. The higher the altitude the less fuel you need for a proper A/F ratio. There is less air at your house than most other folks.

Click to expand...

I do know I need a HA jet. Wasn't aware that lowering the float could cause it to run lean. May try that.

slomo said:

Removing the air filter is for TESTING ONLY.

Click to expand...

That's all I'm doing right now. I haven't left it running more than a minute. Too much smoke.

slomo said:

Stop buying ebay Chinese carbs. Put the OEM carb back on. Get a high altitude main jet for it. Clean/flush out your fuel tank and install ALL new hoses from tank to carb. Blow out tank with compressed air.

Click to expand...

Have you priced a new carb for this? They are at a minimum $200. This thing is only used to pull a rake in the yard and maybe haul a trailer. I have a Craftsman that is capable of doing that also and we use that for mowing. I have pulled the deck on the LT166 and just want to use it to do misc stuff. It was built around 1998 (not sure) and I don't think it's worth that price just to do misc stuff. $30, I'm OK with.

After doing some further testing on the old carb, it's the fuel shutoff solenoid that isn't working. Again, replacement cost around $150. Same as above paragraph.

These prices are ridiculous and I just can't justify them.

I contacted the eBay seller and they don't have any jets for them.

Don't get me wrong, I do appreciate ya'll trying to help me but dumping $150+ into is hard to justify. I'm willing to work to fix it, but not dumping money into it when it's old and beat up. Previous owner(s) didn't treat it right. Even the hoods broken and has to be tied on.

As a follow-up, I have found cheap solenoids on eBay/Amazon but I don't know how to tell when this LT166 was built and there are 2 options listed. It looks like it may be the early model (of course).

Anyone know where I can look to find the build date?

Thanks again.

Here is what info I have on the Mower/Engine

John Deere LT166
B&S Vanguard
Engine 303777-1147-E
Fuel Shutoff Solenoid
947 806472 Used After Code Date 98062600
947B 807744 Used Before Code Date 98062700

MadMopar said:

Here is what info I have on the Mower/Engine

John Deere LT166
B&S Vanguard
Engine 303777-1147-E
Fuel Shutoff Solenoid
947 806472 Used After Code Date 98062600
947B 807744 Used Before Code Date 98062700

Click to expand...

Bypass the anti afterfire solenoid on carburetor so you don’t have to spend $150 on part. Do not throw that OEM (probably Walbro) carburetor away. Measure bore where jet goes in and threads. Look around for smaller jets and buy a couple. Go smaller than you think and you can drill them out with micro drill bits until air/fuel mixture is correctly reached.

The Tiger is Briggs is getting to where they don't stamp the jet size on the jets. I tried for several years to get other techs to send the pns and stamped sizes to me so I could make up a cross reference chart. Currently I only have a few Nikki listed as they are the ones I have used here.

I just recently ran across a seller claiming two different Briggs jet part numbers were the same one when I definitely know a 111 and a 118 are not the same jet.

Tiger Small Engine said:

Bypass the anti afterfire solenoid on carburetor so you don’t have to spend $150 on part. Do not throw that OEM (probably Walbro) carburetor away. Measure bore where jet goes in and threads. Look around for smaller jets and buy a couple. Go smaller than you think and you can drill them out with micro drill bits until air/fuel mixture is correctly reached.

Click to expand...

Man, I didn't even think about that. I still have the original carb and I'm pretty sure it does have the HA jet in it. It should still be fine. Last time it was used it had run out of gas (solenoid) so it should be OK. I have used starter fluid to run it so I'm sure all the gas was sucked out of it.

How important is that solenoid anyway. Do these machines have that much of a problem with afterfire?

Just have to find a bolt that fits. Don't want to damage threads in case I do need that solenoid.

I have the parts manual for the engine and it actually shows and gives a part number for a plug (just looked). Apparently it is bypassable according to B&S since they make the plugs.

Walbro are usually 5/16-24 and Nikki are M8-1.00. Only about 5mm in length.

StarTech said:

Walbro are usually 5/16-24 and Nikki are M8-1.00. Only about 5mm in length.

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Accordingly, it's a Nikki. Went to Ace with the carb and the solenoid and got an M8-1 and a couple of 5/16 brass washer (bolt was a little longer then the solenoid). Spent $2.31.

Just cranked it and as soon as the bowl got filled up started right up and is running like a champ. No more black smoke and is nice and smooth. Perseverance has paid off.

Now to put it all back together and go for a long overdue ride.

StarTech said:

The Tiger is Briggs is getting to where they don't stamp the jet size on the jets. I tried for several years to get other techs to send the pns and stamped sizes to me so I could make up a cross reference chart. Currently I only have a few Nikki listed as they are the ones I have used here.

I just recently ran across a seller claiming two different Briggs jet part numbers were the same one when I definitely know a 111 and a 118 are not the same jet.

Click to expand...

The jet looked like it was stamped maybe (0) and an 8. The (0) is off the edge and looks almost double stamped. The other # is definitely an 8. Could be 118 but wasn't clear. I'm 99.9 % sure this the HA Jet since it is running so well and I'm around 5500'. The ref # in the Engine breakdown is 72A and the part # is 694069 for the high altitude jet. I'm sure that is what was in the carb. Hope this helps you somewhere and helps anyone else looking for it. This info is from the B&S Vanguard parts breakdown manual.

Thanks to all who have taken the time to try and help me and a special thanks to Tiger Small Engine and StarTech for the answers I needed.

After running for a bit, started running rough and slight smoking. Remember the adjustment on the top of the carb and smoothed out with adjustment. Even had to lower the idle adjustment, running too fast at low idle.

Took it for the long awaited ride and ran good. Back in business.

Jets should be reamed rather than drilled and by preference using a pin drill
Any distortions to the surface of the hole will make a drastic difference to the flow rate
jet reamers are very very expensive
Micro drills , particularly those cheap sets from China are rubbish and will be all over the place diameter wise
I stuck some under the macroscope and found that all bar 1 were sharpened of centre so all will cut a bigger diameter thole than the advertised size
Apart from that the increments are way too big for stepping
The other thing you are missing is that untill you turn the blades on the mower is running off the idle jet, not the main jet so stufing around with the main jet will do nothing to make the engine stop blowing smoke standing still
This is why the manuals go to the effort of calling 3600 rpm "HIGH IDLE" and not running speed .

bertsmobile1 said:

Jets should be reamed rather than drilled and by preference using a pin drill
Any distortions to the surface of the hole will make a drastic difference to the flow rate
jet reamers are very very expensive
Micro drills , particularly those cheap sets from China are rubbish and will be all over the place diameter wise
I stuck some under the macroscope and found that all bar 1 were sharpened of centre so all will cut a bigger diameter thole than the advertised size
Apart from that the increments are way too big for stepping
The other thing you are missing is that untill you turn the blades on the mower is running off the idle jet, not the main jet so stufing around with the main jet will do nothing to make the engine stop blowing smoke standing still
This is why the manuals go to the effort of calling 3600 rpm "HIGH IDLE" and not running speed .

Click to expand...

I wouldn't mess with reaming jets. They aren't that expensive to get the correct one. My old carb has the correct one and there is no smoke now with idle up to flat out.

I'm going to assume that you missed the part about my removing the deck and only use it for hauling a rake and trailer around. We have a Craftsman 52" we use for mowing. I just 'punch it' for speed.

I doubt that carb has an HA main jet. Unless the mower came from some really good dealer (long shot) at 5500 feet. And they knew about this rich condition. Maybe it does??

Guessing it will still run rich and be down on power compared to a sea level mower. Lower the float level like I mentioned. It costs NOTHING.