Hybrid Harley/Columbia:Have to choke to start when hot.

Yttermayn

I have a columbia par car from the 80's with an older harley tillotson carb, air filter, and muffler. Last year I replaced the old crank case seals on the recommendation of this forum. I recently cleaned the carb out (but didn't mess with the welch plugs). I was having fuel problems and discovered that a hole had been worn into my fuel line elbow. I fixed that and also replaced the fuel line and clamps, so everything is tight now.
The thing starts nicely from cold with full choke. However, even though it's hot I have to choke it for a second when I start. I rechecked the crank case seals using the spray starting fluid near the seals method, no dice. Anybody got any ideas?
Thanks!

BGW

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backyard

Sounds like you have air coming into the engine that is bypassing the carb. Blown gasket somewhere, maybe a hole in the fuel pump vacuum line. That may be why you're needing extra fuel.

Yttermayn

I did just replace the gasket between the carb and engine, how would I tell if there's a leak elsewhere?

backyard

You could spray starting fluid around the area and see if the engine picks up. Don't choke it anymore than you have to or you may not notice it. I see you've done that already. Don't let the engine get hot and then try to spray. Don't rule out your carburetor being clogged or faulty or maybe you just need to adjust the low speed or idle fuel adjustment if there is one.

Yttermayn

I have fiddled around with the one adjustment that is present on this carb, and it doesn't affect this problem. If I open it too far, I get backfires, and if I close it the engine won't run. I find that about 1.5 turns works well.
I tried spraying the whole **** engine down today, no luck. I might pull the carb AGAIN and maybe have at those welch plugs and borrow a socket small enough to unscrew the jets. Maybe something in there is plugged.

backyard

I've got a walbro carb that I've cleaned twice and it's still plugged up somewhere. What kind of carb do you have? Really thats all I can think of besides maybe a blown head gasket sucking in air, but I'm sure you would have noticed that.

Lochlin

It's not all that unusual to have to choke a two cylinder for a moment or two even when warm so don't kill yourself trying to make things so that you never have to choke.

Also, the choke mechanism itself is another fuel adjustment point over and above the screw on the carb. On both of my Columbia's I have the choke cables adjusted to allow for just a bit of choke at all times (even though the choke lever shows "no choke"). Granted not much, maybe 10%.

Another thought is that your cart should be capable of accepting a Mikuni carb, either BV-19 or BV-24. Those were used on 80s era EZ Gos. I like them a lot better than the Tillotsons and the Walbros because they are a much simpler design. That's just me though. You can get knock off Mikunis for $40 or so. I have a ton of success with them.

CharleyL

If you are certain that the carb is clear, the timing may be slightly off, but don't try to adjust the timing without the proper procedure and tools for doing it.

Moving this problem to the Harley sub forum (above) will likely get you many more experienced help responses to your posts since you are asking questions about a Harley motor and carb. I doubt that many Harley owners even look down here.

Charley

Yttermayn

Update : I've figured it out!
I was digging around in the carb and noticed that the rocker arm had a well worn spot where the metal diaphragm thingy slams into it to pull the needle out. I reasoned that after 40 years it might be bent in a little. So, I pried it out just a smidge and reassembled. Boom! No start up trouble.
There is an increase in backfires, but that is preferable to crappy performance.
Thinking about that more I realize that the rocker was probably not the only worn part; probably the whole needle /rocker/diaphragm mechanism is sloppy. Bending the rocker out compensates for the slop but at the cost of extra fuel making it to the hot exhaust for backfires.
Before you say it, I did order a carb kit. Unfortunately, I got the wrong one and it's not returnable. It may be awhile before I try another.
Also for clarification : its a Columbia engine fitted with a Harley carb, airbox, and muffler.

backyard

Sounds like you have the tillotson carb. If I were you, I would order a chinese mikuni bv19 or bv24 and replace it. They aren't much money but you'll have to move the linkages around. The tillotson is notorious for having priming issues but that can be compensated for in a couple ways.