1980 Sportster dies when I rev the throttle quick

[mscruton]

I have a 1981 1000cc Sportster (I think its called an ironhead) with a Super B carb on it. I don't know much about carb adjustments but suspect I might be having a problem with it? When I rev the throttle quick the bike doesn't respond and then dies. Or if I'm trying to go up a big hill and give it more power, it dies. The bike seems to run better when I rev the throttle if I have the little "choke" thing on the carb pulled up and left in the "up" position, rather than twisting it so it drops in the "down" position, but someone told me its not good to run it with it in the "up" position as it is like running with a closed choke? Not sure what I should do or try to adjust. I don't have the cash to take it to a garage. Any thoughts? Thanks.

[Ratbike]

With the info given, it sounds like you are not getting enough gas. When you have the choke pulled out you are forcing the carb to get less air and more gas. The main jet could be plugged. Do you have the repair manual for your bike?

[Ratbike]

What led up to this condition?(ie changes you made, maintence, storage)

[Wide]

Hey mscruton

Welcome to the forums


You could have a few problems here, your petcock screen is clogged, air cleaner clogged, carb needs a rebuild, intake gaskets.

These are the common things on your bike, they are all not that hard to do.

Did this just start?



Hope this helps

[mscruton]

Thanks for your suggestions. The bike had been in storage for about a year. I've ridden it a few times last month without any problem. Then one day it just started doing this. I'm not sure what brought it on. I'll check the air filter and petcock like you suggested. About an inch away from the "choke" is a small screw with a small turning bar that I tried turning a little after this all happened. I'm not sure if I turned it back to where it should be either. If I turn it in all the way, how far off should I back it. I don't think its the idle screw because the idle didn't change when I turned it, I don't know what it is exactly only now my bike won't start at all so I guess I've got it turned to far one way or the other. Thanks.

[Scarecrow]

Ss carb that's been sitting..sounds like a clogged accelerator pump. Or possibly just a misadjusted accel pump. Do you see a spray from the center of the carb body as you pull the throttle?

If not, open her up and clean well. Carb cleaner works well, but if it's too strong you may have o-ring problems. I prefer PJ-1 cleaner. It's a little harder to get carbs clean, but it won't ruin o-rings.

The screw you turned sounds like the accel pump adjuster, it usually doesn't take much once the pump is working. I would start at 1 turn out, and go from there. At idle pump the throttle, and listen, add or lessen as necessary.

I know there are lot's of folks here that are better at the SS carb than I..

[nucklheadsports]

I got an 80 Sportster with a SS Super E carb, and a couple years ago when my in line fuel filter was worn out and the gas I bought super junk I had to get a repaire manual from S and S. You ought to get one too. That helps explain all the cleaning, adjustment and jet handling. I got that finally done last year after I got jets that work at my homes altitude.
Oh and just don't drop and loose one of the tiney ball bearings like I did.

[mscruton]

My 1980 Harley 1000 Sportster won't start and I think its because someone twisted around the little idle mixture screw (located beside the enrichment device). I have no idea what it should be set to. If I screw it back in all the way, how many turns will it take to get it close to where it should be? I've tried a few positions without luck. I may be flooding it?

As I mentioned in a prior post (Sportster group), before this happened the carb was also giving me trouble when I'd roll on the throttle too quickly it would die out. I could only roll on the throttle slowly. It seemed hesitant on hills too when I'd roll on the throttle. I found a diagram of the carb at this website, but mine is an old model so I'm not sure if everything is still the same on it and it doesn't tell me much about tuning it up http://www.nightrider.com/biketech/d...als/superb.pdf

I'm not a mechanic, but enjoy tinkering. Any suggestions or advice is appreciated. Thanks

[Wide]

Turn the screw in untill it bottoms out, not too hard you dont want to damage the taper on it.

Now back it out 1 3/4 turns, thats the default setting.

Yes it sounds like your accelerater pump may be bad, do like they said & pull the air cleaner off & twist the throttle to see if any gas squirts in, if not you will need a rebuild kit from S&S


I am moving this to your other topic to aviod confusion

[mscruton]

Thanks for the tip, I'll try that tonight. However, my understanding is that the Super B doesn't have an accelerator pump or a choke either. I'll look inside the throttle body though to see what happens when I roll the throttle slowly.

Thanks again.