218 runs great----when fully choked

[squirebill]

So was trying to get my 218 running after it sat for a full year without being started.  Drained old fuel.  Pulled choke horn and upper cover off the carb.  All fuel had evaporated and left a white powder residue in the float bowl and throughout the carb. Removed carb for a cleaning with spray carb cleaner and while disassembled threw  the parts in my ultrasonic cleaner with hot water and detergent.  Assembled carb and reinstalled.  Filled carb with fresh fuel and  tried to start. No start. Dumped some fuel into carb while holding throttle open.  Engine started but only ran for a few seconds.  Tried to restart but a no go. More gas down carb and again run for a few seconds.  Decided to install choke push/pull control.  Applied full choke, two strokes of throttle and engine started.  Went to take choke off and engine stalled.  Choked again and started engine .  Left it fully choked and engine runs great.  Even revs up when throttled up. I'm  guessing I have a vacuum leak.  Clamped off hose going to vacuum wipers and disconnected vacuum advance tube and capped port at base of carb. Again, engine only runs when fully choked.  I'm looking for recommendations to check for vacuum leaks of the carb.  Have seen people use spray carb and brake cleaner but also read on this forum about heated carb and brake cleaner developing into phosgene gas. Want to avoid this since is adjacent to hot exhaust manifold.   Have also read on this forum of using a unlit propane torch.  Any other recommendations.  Regards to all.

[Sniper]

2 minutes ago, squirebill said:

brake cleaner developing into phosgene gas

 That would be the chlorinated brake cleaner. 

 

When I rebuilt my carb the kit came with multiple top and bottom gaskets as well as the base gasket, you had to pay close attention to putting the correct gasket back on. 

 

Then there are the bolts that hold the carb together, they can loosen allowing a vacuum leak.

 

 

[keithb7]

How long was carb in ultra-sonic cleaner?

Air leaks indeed could be suspect. How about an unlit propane plumbing torch?  To check for leaks. 
 

There are passages in the carb base throttle plate spacer and gaskets as Sniper mentioned. Indeed I agree, could a hole inadvertently be plugged by improper reassembly?

[squirebill]

Carb parts were in ultrasonic cleaner for half hour with detergent and then for another half hour on rinse cycle.  As not recommended, old gaskets were reused.  Intend to disassemble again, make new gaskets and reassemble.  Was looking for vacuum leak test recommendations to verify gaskets were in fact leaking. 

[Los_Control]

I always use carburetor cleaner to spray around carburetor while running.  Does not hurt anything & you will notice a different in idle if it gets sucked in.

 

My weak brain is telling me that putting on the choke shuts off the air and enriches the fuel mixture.

I would think a quick spray around the carb & vacuum lines would tell you if it is a external issue.

 

While I have rebuilt my B&B carb & set it on a shelf while I installed a purchased rebuilt carb ...... I just never bothered to remember the specifics of our carbs when I can look it up later if needed.

 

A typical carb will have a main jet, then there is the idle circuit. ..... having to run with the choke on often would indicate a plugged idle circuit. .... assuming there is no outside leaks.

 

Grrr ..... there are 2 little ball bearing in our carbs, they are different sizes .... very important to get correct size in correct hole ..... I wonder if that affects the idle circuit?

I do not remember.

 

Other advice I can suggest. I have watched a youtube channel for a few years. He rebuilds a lot of different style of carbs and uses a sonic cleaner.

Years ago when he first started with it, he used detergent in it & tried several kinds of detergent.

He eventually switched to Berrymans chem-dip carb cleaner. The detergent was just not doing a satisfactory job on carburetors.

While it may work for you, maybe you will need to add compressed air & thin wire to manually clean passages?

 

Last year or so the guy bought a new larger model sonic cleaner for carbs & uses Berrymans in it, the older smaller sonic cleaner he uses detergent in it for jelery or other items.

[Los_Control]

Here is a video I followed to assemble my carb.

 

 

[9 foot box]

   When I had a problem with my idle circuit not working without choke being partially closed, I took the top off the carburetor and cleaned the air tube just above the choke plate. It had a bug or some crud in it. Rick D.

[squirebill]

Found the culprits!  The upper and lower gaskets on either side of the metal insulator were shifted/misaligned allowing for a vacuum/air leak.  Note that the bore of my insulator is 1.5625 inches= 1-9/16 inches and is correct.  The insulator gaskets that were in my carb rebuild kit were all 1.725 inches.  Too much fiddleing and didleing required to make sure it all aligned with no leaks so made my own with correct 1.5625 inch bore.  All good now.  What was amazing to me was how well it ran at full choke. The leak path for the lower gasket was shaped as a crescent with maybe .050 inch maximum width at the center the tapering off to zero at each end .  It was about a 1 inch long arc. When I compare this  to the flow area of my 1-1/4 inch venturi diameter, doesn't seem to make sense.  Another thing to ponder.     Best regards to all.   

[Doug&Deb]

Glad you got it figured out. Sometimes finding the problem is the worst lol

[Go Fleiter]

fine result!

And I feared You had to search for the 2 small balls of the carb :))