If you like our site, please consider joining our club!
By joining you will help ensure that we can continue to provide this service
JOIN HERE!

1/26/83 Carb Leak through 181 air screw

Post Reply
silverdaggr@gmail.com
Posts: 11
Joined: Sun Dec 20, 2020 3:32 pm

1/26/83 Carb Leak through 181 air screw

Post by silverdaggr@gmail.com »

Greetings,
I have a 1964 BMW R27 S/N 383xxx. I have had the bike in my shop since December of last year. I ordered an overhaul kit and a spare gasket set for the 1/26/83 carburetor right away. I cleaned the carb, replaced all of the gaskets, the jet needle, set the clip in the second hole from the top, replaced the air screw with the sleeve and cap for drainage, replaced the accelerator pump and main jet, and the main jet. Now I have it ready to run.
Last week we tried to start it. When the fuel tap was opened the fuel dripped out of the idle air screw at a fairly high rate. We shut the tank valve, put some fuel in the cylinder. It ran long enough to run out of fuel.
We isolated the problem to the float needle and seat. We weighed the old brass float and needle: 14.5 grams, and the new plastic float and new needle: 14.4 grams. It seemed that the float did not have enough buoyancy to seal the valve. Both sets seemed to fail alike.
I took the carb apart again and cleaned it again with carb cleaner, paying particular attention to the float bowl seat with a carb bristle brush. I soaked it with cleaner until the drip out showed no residue. After I put it back on the bike the idle air screw did not leak initially. So, we primed the cylinder, turned on the petcock and kicked the bike. Again, the carb started leaking. A suggestion was to clean the float bowl cap. I took it apart again and thoroughly cleaned the needle top seat in the cap. I did not see any deposits in there.
When I put it back on the bike and opened the fuel petcock, there was no leak. We primed the cylinder and kicked it.
When it started it ran at a very high speed, my guess about half throttle. There was little or no response to the idle adjustment screw, except there was a setting where the engine was running smoother. The fast idle was making me nervous so we shut it down, looking for an adjustment for the throttle.
We started it again. The engine was running at a high rate with little or no throttle response, except that opening the throttle would increase the speed, which fell off with the throttle all the way off. I pecked the slide body to see if it was stuck. With the bike on the center stand we put the bike in gear, applied the foot brake to slow the motor down to near idle, then released the brake. Engine speed went back up to beyond fast idle… Then we noticed that the carb was leaking out of the air screw again.
I sent the carb to Bing in Kansas. When the carb came back the carb did not leak until after the bike started and ran for over a minute with some throttle response… Then it stumbled to a halt and I noticed that the carb was leaking out of the air screw. I assume the engine flooded out.
I found a 1/26/83 used in Greece. Yesterday I transferred all of the jets and needles to the replacement and changed out the gaskets to the 1/26/83 from Greece. I used the cap throttle cap and slide with the needle from my original carb put a new style air screw in.
Today when I opened the fuel valve the Greek carb leaked exactly like the original one… I think I am missing something. Can you diagnose the problem and recommend a fix?


Regards, Morgan

xackley
Posts: 111
Joined: Sat Oct 14, 2006 4:09 pm
Been thanked: 2 times

Re: 1/26/83 Carb Leak through 181 air screw

Post by xackley »

silverdaggr@gmail.com wrote:
Sat Sep 11, 2021 8:18 pm

I found a 1/26/83 used in Greece. Yesterday I transferred all of the jets and needles to the replacement and changed out the gaskets to the 1/26/83 from Greece. I used the cap throttle cap and slide with the needle from my original carb put a new style air screw in.
Today when I opened the fuel valve the Greek carb leaked exactly like the original one… I think I am missing something. Can you diagnose the problem and recommend a fix?


Regards, Morgan
I had to wonder why you didn't bolt up the one from greece before switching out parts.
On my R69 the only cause of overflow when on the center stand is when the float sinks, the needle isn't seating, or the bottom of the neeedle got stuck in the guide at the bottom of the bowl. There is nothing else that controls the level in the bowl.

Don

Edit: one more possibility. The rod of the primer button is holding down the float.
1958 R69, 1972 R75/5, 1980 XS650, 1982 GL1100, 2003 guzzi ev, 2017 guzzi V7!!!
All on the road, going no where in particular in the Finger Lakes of New York

Post Reply