problems keeping it from stalling out

[cmattina1]

78' special

So, I just bought this today. Looked at it several times and it started fine every time (never took it for an extended test drive though). I drove it home today, about 20km or 12 miles, parked it for a minute (engine off). Started it a few times with the kick just to see how it worked, and it worked fine.

Let it sit for 4 hours or so, and now when i start it, it will stall unless i keep the choke open and continuously rev it. Let it sit for 2 hours with the choke and petcocks closed, engine cold, started right up, but again, would stall out and backfire a bunch...

I figure it is a problem in the carb, or maybe I flooded it by accident.

I MAY have parked it with the choke open... Could that flood it?

 

[Patches]

It's not flooded.

Sounds like you probably need a good carb cleaning. It never hurts, especially when you don't know when the last time they were cleaned. Be sure to get yourself familiar with the carb guide in the tech section, and check for air leaks, and check petcocks.

Also, when you ask technical questions some bike model and year info helps your cause.

 

[cmattina1]

Thanks. I was beginning to see that the symptoms point to a it a carb cleaning, though the previous owner, a certified auto tech, told me he recently cleaned out the carb and it looked okay.

I assume, but driving it 12miles and loosened up all the grit in there and it's clogging the jets?

 

[Patches]

Be sure you are running some in line fuel filters. They are cheap insurance.

 

[cmattina1]

I should have mentioned the backfiring also. I just went and started it after letting it cool completely and it fired right up, but again, it wouldn't sit at idle without stalling

 

[XSLeo]

Could be the idle speed is set to low.
Leo

 

[5twins]

Although many do, you can't expect to buy a 30 year old bike, hop on it and ride off into the sunset, lol. I would start with a complete tune-up. I would at least remove a float bowl to see if the carbs look dirty inside. If you still have points, it could be a timing issue.

 

[cmattina1]

I hear ya there, and it wasn't priced high. I am just hesitant to start taking apart and cleaning a carb that was "supposedely" rebuilt last season...
Could it still be a timing issue if it has started up and idled fine for several starts over the past week (few day intervals), but then after driving 12 miles, now i have these issues? I understand how that may have loosened up some grit inside clogging the jets, especially if the previous owner didn't actually clean out the carbs in the rebuild.

One thing he did mention is that he changed the stalk airfilter to the K&N pods but left the jets the same: He said he changed the jets to what had been recommended to go well with the new pods, but found the original jets worked better so swtiched the back...

 

[5twins]

You may not need a carb rebuild but you have to at least look in there to see if they're clean. And P.Os by the way, are notorious lairs, lol. You should be able to drop one of the float bowls, carbs still in place, using a stubby screwdriver. Don't drain it, drop it with the fuel in it. Then you can look in there and see if there's a bunch of crud floating around in the gas or if the insides of the bowl are all varnished up.

One of the worse things you can do is run dirty carbs. Then you spread what was just sitting in the bowls all through the carbs and plug up much more stuff. And yes, it could have happened in 12 miles, it could have happened in 2.

 

[cmattina1]

okay thanks, thats a good start. I'll look at them tonight and I was also going to check out the plugs too, incase they're fouled, though, the P.O. did say they are brand new, which they appear to be.

I guess my plan of action will be to: check float bowls; check plugs; adjust idle speed slightly; rebuild carb if nothing else works.