I just bought a 71 XLCH. It ran when I road it but I had limited Time. Seller said carb ahd been gone through?? Well that wasn't so!! The bike has a Keihin butterfly (Sportster 76 to ?) I will need to replace this carb, as it sat for 16 years with the bike. I would like to know of anyone's experience with this carb. I don't have the bucks for an upgrade (S&S)now so its a bendix or this one. Any thoughts. I had a 1971 XLCH in 1973 and a 1969 XLCH in 1978, but I have been 4 wheelin' until now. Also I want to thank all you guys taking time to put good stuff on these scooters on the net. Waiting for

 

Not that you care or it makes any difference but a 1971 XLCH came with a Tillotson carb. I threw mine away in 1973. Worst carb I have ever dealt with.
I do not know much about a Keihin, but the butterfly model should be a good carb.
I do not know about an S&S carb either, but I think they are over rated.
I do know everything about a Bendix carb. Good carb with only one weak point that I know of.
I also know much about a round slide Mikuni carb.

If you are going to buy a carb, a Mikuni would be the hands down favorite. If you want one crank kick starting this is the one to get.
Second choice for me is the Bendix. Good carb and reasonably priced. I would buy the model with the adjustable main jet.
Hope that helps some.
pg

 

Thanks for reply. You are right, my 71 back in the day had a tillotsin with the 1" wide adjustment screw on top. Right now I don't think I can deal with a mikuni swap. I am also just with garage (after 20 years) so I am building tools as well. I want to get this Bike running as cheap as possible to see if I have any other problems?? I read your post about the breather valve between the engine and primary. When I drained the primary case it had regular oil and way to much. I filled it with 1.5 pints of that special fluid for tran and primary. The engine oil was low so I may have that breather issue. The bike sat for 16 years. I bought it from a guy who got it from the one who stored it. He is a bike mechanic but not harleys, let alone ironhead. He seems OK, but when I asked him about the primary, he did not knoe it needed oil?? Supposedly the bike fluids were drained during storage. Anyway sorry about long wind, but its nice to speak to someone who knows what he's talking about. Thanks again!!!

 

I think draining the fluids for storage (other than fuel) would be a bad..? Cant say I really know tho! I've never stored one.

 

OK, a couple of things here need to be addressed first.
The engine oil sits inside the tank. The oil line goes from the tank bottom down to the oil pump inlet. Inside the oil pump there is a ball check valve. This is a simple ball bearing resting against the seat in the oil pump body. A spring exerts pressure against the ball to keep oil from leaking into the bottom end when the engine is not running.
When the engine is started, the oil pressure raises the ball off it's seat and oil is pumped throughout the engine. That is how the thing works.

What happens when a bike has sat without running for a long time (even 3 weeks can be long enough) the oil begins to leak past the ball seat. Oil flows into the bottom end of the crankcase.
If enough accumulates, then the next place it flows to is through the breather valve into the primary and transmission.

This is what happened to your bike. The oil tank was low because the oil drained pass the check valve and into the lower end. Then it continued to flow into the primary and transmission.
That is the reason you had such a huge amount of oil there.

Now, the modern primary and transmission lube sold at the shops is not what you want to use in this Sportster.
Remember, you have that breather valve that allows some engine oil to pass from the engine to the primary area. Not much, but some. So the oils mix.
You should use the exact same oil in the primary and transmission as you use in the engine.
That oil is 60wt. If you live in a really cold climate you could use 50wt in the winter, but who wants to ride in that kind of weather?
I suggest you drain all of the oil out of the trans and primary.
Buy some 60wt oil at a Harley dealer and put it in the oil tank (3 qt) and in the primary/transmission (24oz).

Regarding the carburator.......
I can understand not wanting to spend money on a new carb. Most likely no need to either.
The Keihin butterfly carb should be just fine.
You may want to remove the float bowl and check/set the float level and replace the bowl gasket with a new one.
Get some specs on the carb before you go taking it apart.

Starting issues on a bike that has sat for many years is almost always a problem with the ignition points and sometimes the carb parts will 'dry out'.
Do you have trouble starting the bike?
If so, what happens when you crank it over?
pg

 

The guy I bought the bike from said he refilled the oil tank, after all fluids were drained before the srorage. Maybe he filled it with less than the 3 quarts. It is interesting that the harley Manuel said the same thing as you about the primary oil, but I thought it was wrong?? I have been told the primary on sportsters 71 and later used this transmission/ primary case oil. The drain plug for the primary is at the bottom of the case, yes? Small phillips head screw. The bike starts pretty well, but won't run when warmed up. Just after starting it "runs" below 3500 rpms, then begins to back fire and miss when you open the trottle. Accelerator pump does not shoot gas into butterfly, but the plugs are BLACK. Way to much fuel. I bought 2 bendixes and a rebuilt kit. Then I saw a very good looking rebuilt carb on Ebay just like the Keihen on the bike. I can do one of these for $150.00 +-. Later I can talk to you about how to do the mikuni.

 

Listen to Piniongear. I did the double oil change a few days ago on my 70, only I used 50 weight because it has been so cold lately. Anyway, the thing is running like a champ. Much smoother than before I changed the transmission oil. It even kicks a lot easier. I also emptied out the engine oil through a plug dead center in the bottom of the engine. Keep reading. These guys really know their stuff. Good luck with the bike.

 

On mine, it is at the bottom of the case, toward the rear. But it is not a phillips head screw. It is a nut (9/16 if I remember correctly) with a magnetic washer.

Oh, and careful with these plugs. I'm told they strip very easily and they are a pain in the *** to fix.

 

I plan to. I have been reading these posts on the archive, but finally started posting. Take care C. Numb Nice Bike!

 

If you are prepared to spend $150 on a 'rebuilt' carb I suggest you first price out a brand new Bendix.

If your accelerator pump is not working that may be a cause of your problems. When the engine is idling there is a strong vacuum in the carb venturi. As the butterfly is opened quickly the vacuum falls. Here is where the accelerator pump comes into play. It squirts fuel into the venturi until the carb can recover from the quick opening of the butterfly.

The main cause of backfiring is O rings that leak air (we are talking about the O rings in the inlet manifold here) and ignition timing is the second cause.

First, decide on what you intend to do about the carb. Buy a new one, a rebuilt carb, or repair the pump inthe Keihin.
Then you will be ready to check the O rings for leaks.

If it does not run well after the carb issues have been taken care of it is time to go into the ignition. Not before.

Do only one thing at a time. If you try doing several things at once all that will happen is you get stretched in different directions and nothing gets repaired properly. Take it one step at a time.
pg