Briggs 'Quantum 6.0' Flathead top no load 2600RPM

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Colt45ws

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Aug 15, 2006
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I have this engine on a oversized push weedwacker (forget the technical term atm) and I recently got it running after a 3 year hiatus. I originally just took the carb apart and cleaned it out, filled it with fresh gas and that got it running, but it was running pretty slow, and it surged at idle. I didnt have any way of measuring but it sounded slow so I bent the governor spring that goes between the throttle and the governor arm to get it to have more speed.
I noticed the spring was pretty rusty so I ordered a new one along with gaskets so I could do the carb properly. I got the spring on today and its still pretty slow, and I have a laser tachometer so I was able to measure it as 2600RPM. I can't even measure the idle because it surges. I don't really want to tweek my new spring so Im wondering what could be wrong with the governor to make it want to run slow like this?

The Model on the engine is 122H02-0110-D1
 
Replace the carb. $15 to $22 on average for a new carb. Don't even bother rebuilding them when a new one is so cheap. Your carb is still plugged up and running lean.
 
Nothing new it sat for a while. Put about a 1/2 cup or so of berrymans b12 into the gas tank too it off with fuel and run it a bit.
 
I thought I cleaned it out pretty good. I soaked it in brake cleaner and then blew everything out with compressed air. Ill try the berryman first.
 
Originally Posted By: bubbatime
Replace the carb. $15 to $22 on average for a new carb. Don't even bother rebuilding them when a new one is so cheap. Your carb is still plugged up and running lean.


This is what I'd do as well. I've really thought I had them clean before and they still wouldn't run right, new carb fixed the problem.
 
Originally Posted By: Colt45ws
I thought I cleaned it out pretty good. I soaked it in brake cleaner and then blew everything out with compressed air. Ill try the berryman first.


Carb rebuild kit = $12-$14
Berrymans B12 = $8
Labor = hours and hours
Put it together = Still doesn't run right
Take it apart = more hours and hours of soaking and cleaning
Doesnt run right = spend 30 minutes writing a post on BITOG asking for help on how to fix it

OR

Option 2
buy a new carb off ebay or Amazon for $15-22 on average
Replace carburetor in 3 minutes
Engine runs like new. No headaches, no hours of soaking, no hours or taking it back apart for another cleaning, no posts on BITOG.


I realize you have already wasted a bunch of time and money trying to fix it. FOR FUTURE REFERENCE, BEFORE YOU DO ANY CARB WORK, look up the cost of a replacement carburetor. If its $100, rebuild it. If its $20, REPLACE IT. Don't waste your time or money rebuilding a $20 carburetor.
 
Alright alright I get it, Ill order another carb. I figured I'd tinker with this one and see if I could get it running right on the cheap. I don't have a regular job so I can spend hours on it, though Im probably only into it about two hours and the post I made here took 5 minutes.
 
Originally Posted By: bubbatime
Originally Posted By: Colt45ws
I thought I cleaned it out pretty good. I soaked it in brake cleaner and then blew everything out with compressed air. Ill try the berryman first.


Carb rebuild kit = $12-$14
Berrymans B12 = $8
Labor = hours and hours
Put it together = Still doesn't run right
Take it apart = more hours and hours of soaking and cleaning
Doesnt run right = spend 30 minutes writing a post on BITOG asking for help on how to fix it

OR

Option 2
buy a new carb off ebay or Amazon for $15-22 on average
Replace carburetor in 3 minutes
Engine runs like new. No headaches, no hours of soaking, no hours or taking it back apart for another cleaning, no posts on BITOG.


I realize you have already wasted a bunch of time and money trying to fix it. FOR FUTURE REFERENCE, BEFORE YOU DO ANY CARB WORK, look up the cost of a replacement carburetor. If its $100, rebuild it. If its $20, REPLACE IT. Don't waste your time or money rebuilding a $20 carburetor.



+1

I hardly clean carbs anymore unless they are expensive to buy new.
 
Is there a throttle cable on this machine or is there a set screw or a spring that could go into several different holes to adjust the speed?
Usually there is some sort of adjustment for the top governed speed.
Maybe a cable adjustment if it has throttle cable.
The idle surge does suggest a lean mixture so you very well could have a partially clogged jet.
 
Also if this carburetor has welch plugs there is almost certainly crud stuck behind them that you'll never get out with spray cleaner or soaking.
I have removed them cleaned behind them and replaced them on the more expensive carburetors. If the carb is cheap, a new one is an easier option.
 
Maybe you just have to change O-ring on maniford (where carb is connected on it)...they dry out...and engine get air leak eventually...
 
But hey guys, you forget the soft feeling when managing to repair something even if it takes a few hours and the commercial aspect is moot. A board like this is not so valuable if the standard answer is "buy a new one"... (specially since every other post here bashes regular people from buying new low quality stuff the minute the mower stutters...)
No, try to rejuvenate that old carb first. If it succeeds, the feeling is much better than ebay.
 
Just a question, where are you measuring RPM with the laser tach? If your measuring at the cutting head it's probably slower than engine RPM, most of those trimmers have a belt drive and are not 1:1 ratio.
 
I finally got the time to put the new carb on tonight and its still runs the exact same as it did before. I didnt take the time to tach it because I only had it running for 10 seconds inside my garage. It was still surging too.
So, I feel quite vaildated that my carb job was good enough.
Im thinking about taking it down and seeing if the intake tube that connects the carb to the engine has a bad gasket.
 
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