Help Please on Lightwin Carb issue?

[seakaye12]

quote Mr. Asa:

how do you remove that?

I take an ice-pick…wack it with a hammer to make a hole in it…then pry it out. Some people drill the hole. Just don’t push anything too far in there….you have maybe a quarter of an inch of depth below the freeze plug.

To re-install…place the new plug with the bulge to the top…and tap it with a punch to cause it to expand. Then; I seal it with whatever I have around…nail polish works fine.

[mr-asa]

And what are you looking for in there when you remove it?

[seakaye12]

quote Mr. Asa:

And what are you looking for in there when you remove it?

Well; inside there you will see the orifice where the low-speed needle goes. Just the tiny tip of it will be visible. Then; in the bottom of the chamber there are three holes (I think three) that open into the main passage; right where the throttle plate is. As the throttle plate is opened…it exposes one then two then all three holes to fuel flow…..thereby satsifying the slow-medium speed transition of the engine.

You want to make sure that all that is squeaky clean.

I gotta tell you…in all of them that I’ve removed…..I’m not sure I’ve EVER found anything in there. I do it most of the time anyway….just because it’s so easy and the replacement welch plug is in the kit…..

[mr-asa]

Awesome, thanks for the help.

[billw]

I had a 2 hp with similar symptoms….They have a similar carb….. The upper casting was porous. In my case, I could see the fuel coming OUT around the bowl gasket area, as well as what I couldn’t see going in. Just for fun, I replaced every single part of that carb with another part, except for the upper aluminum casting. It acted poorly every time, until I replaced the casting itself. Maybe you could try that experiment.

Long live American manufacturing!

[cajuncook1]

quote Seakaye12:

The fuel flow is not the issue; although the sintered metallic filter in the tank was a devil to clean. BTW….after trying carb cleaner and brake cleaner to no avail….I found that the “Simple Green” cleaner in warm water did a bang-up job! Lightwin folks take notice![/size]

I find soaking the filter in half water and half Pine Sol solution for a couple hours, rinsing it well, and then blow it out with a air compressor gets a lot of the crud out. You will be surprised what goo comes out that filter. Repeat if necessary.

Well, this works for me, but others have there own preference.

Lightwins and JW’s are a blast to work on 😀

Cheers

[chris-p]

yeah, I had a carb body that leaked air in as well on a 9.5. Try figuring THAT one out!

[fleetwin]

OK, well I don’t want you to mess with that exhaust cover needlessly, especially if no water showed up on the plugs. I surely don’t want you to try to drill out that tiny little screw and get in a real mess if the cover is not leaking the way it is. Yeah, sometimes the exhaust pressure is greater than the water pressure and the opposite can be true as well.
I understand that you cleaned the filter, and thanks for the simple green tip, but how can you be sure that fuel flow to the carb is not the issue. My "pretty" 58 Lightwin was pretty for a reason, I’m guessing no one could get it to run right. I replaced the filter and thought I had it licked, still stumbled and stalled. Then, I found the vent in the fuel cap was plugged, "got it now" I proclaimed. Ran a little better but still stumbled and stalled after running a little while. Finally, I watched the fuel flow out of the copper fuel tube while disconnected from the carb, it was kinda weak. I then poked a metal wire through the brass fuel line, and out popped what looked like a blob of silicone or something rubbery like that.
PS- will reread all your posts, perhaps I have overlooked some of the info you posted.
Any way you could post of video of the engine misbehaving?
OK, just reread all your postings in this thread, didn’t see anything about confirming good fuel flow. In your first post you say the engine doesn’t idle down the way it should. But, in one of your later posts, I think you mention that dead idle performance is good. Maybe you mean that the engine wouldn’t idle properly with the original carb, but idles well with the replacement carb.
My only other concern is a basic one, but I don’t want to overlook it. You are running the engine in a barrel/tank, correct? It is not uncommon for RPM to vary at mid/high throttle settings due to the water/air sloshing around in the tank causing ventilation and RPM fluctuation. Again, try to post a video of the engine misbehaving, maybe that will help us understand what you are describing.

[seakaye12]

Well fleetwin….In addition to cleaning the filter…I cleaned the copper fuel tube and blew through it. I have removed the cap at least once to eliminate the possibility that the vent is plugged. I have not (at least I don’t remember) doing a dribble test. I will do that.

When I said that it doesn’t idle normally…..I should clarify. It idles down very nicely…..but it does so with the throttle lever kinda between START and SLOW. All my other Lightwins need the lever to be slid all the way over to SLOW for the slowest idle. I know that’s not right…but I don’t have a clue as to what if signifies. The synch between the mag plate and carburetor linkage is set correctly…..the carb begins to open right when the throttle lever is set to the two dots on the cowl.

I can do a video. I want to buy a TinyTach or equivalent…..I thought it would be nice to use that in the video…..the sounds in a video can often be deceiving.

[dave-bernard]

If you are running in a barrel it will injest exhaust . use a fan to keep fresh air at the carb.

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