OK guys....hope someone can help. I have an S&S carb on a 111 S&S motor with a spike air cleaner and V&H ground ponder pipes. When the pipes and carb were installed the bike ran great for 2 years. In September I took the bike out, and about 15 miles out it started to back fire sputter, stall, make all types of popping noises. After re-starting several times, feathering the clutch...I got the bike home. Next day drained fuel refilled with new fuel, replaced plugs, took the bike out for 2 miles and it ran fine.
Today took bike out 2 or 3 miles and the same problem started again. Brought it to a bike mechanic and he tried changing the jets to bigger, then smaller and back to original, tried adjusting accelerator screw, adjusted idle screw, new plugs, checked fuel filter and the problem still exists. He mentioned it might be either the coil, or ignition. Does anyone have any other suggestions that may be the answer? Please help!

 

I'm not a mechanic but if you have a steady flow of fuel from the petcock,I would be looking at ignition.My boss had a similar problem on his chop and it was the Dyna ignition.

 

A freind mentioned the ignition...is there a way to test it?

 

So my mechanic just called and said he wants to do a compression check...he suspects it may have a bent valve? Does that make sense?

 

Nop, it makes no sense to me. I read your other post about it being a bent valve. If a valve is bent , it stays bent, and will run like crap all of the time. Need to test the coil, then swap out the ignition with another known good one. I bet money it is your igntion. It is very common on S&S motors. You probably have the Crane HI-4 on that bike. Let us know what you find.Hope that helps

 

A bent valve wouldn't unbend and rebend at will. First thing I'd check is are the battery cables tight, both ends of each, and swap out the plug wires, or at least inspect them and make sure they look good and are seated properly also look at them, and in the coil holes to see if one looks snottier than the other. You'd be surprised what a bad or corroded connection will make a bike do. Run a tank of 94 octane with some carb cleaner aditive, if she's still acting punk, next would be verify timing. Then pull the S&S off tear it down and soak the metal parts over night in the 1 hour soak ****, take an air hose and be sure all the passages are clear Being VERY careful not to bang the accelerator pump jet or let anything hit it, that little slit is only a few thousandyhs of an inch. Trying to work easiest/cheapest on up. You can resistance check your coil, but if the problem is intermittant you may or may not see it. As for checking the ignition, what kind is it? If you do have a crane Hi-4 as the previous poster suggests, they have been bought out by screamin' eagle, not sure if they warrenty the old ones anymore, (Crane would send you a new one 7-8 years later if you sent thme a bad one, no questions asked.) Anyway the fact that it runs good one minute, then like **** then good again, suggests to me either electrical, or something pluging and unplugging something between your tank and intake.
But I'm not a mechanic either, however the reason I have a crane fireball now is I didn't notice the loose battery connection (Hell I needed a single fire anyway). So $400 later when it STILL didn't run right i accidentally discovered the loose positive cable.

 

If the carb was rejetted recently, then the problem is not the carb. Start your bike (in the dark), yes I said in the dark. Check to see if the coil is arcing to the frame or the coil cover. If you don't see that, then get the ol ladies hair dryer. Now, crank the bike up, and poiunt the hair dryer at the coil. If the coil is bad, the heat will cause the engine to start missing and backfiring once it gets hot. Ok, if all that checks out, then remove the points cover and check to see if the lioght on your ignition flickers on and off while running. If it is flickering, that just means you have power to the ignition. Check for bad ground . I will say this again. Your valves are not causing this. I don't believe the carb is either. I have never been able to actually test an ignition. But, if everything else checks out, then it needs to be replaced.

 

UPDATE....

Mechanic was fired. After I told him to put the bike back together I cant afford to do anymore trial and error.....he leaned towards replacing the coil/ignition. LOL what an assh***. I then asked him about the compression test and he said the hard thing was going to be for him to find someone who has the tester for him to borrrow. WTF? I brought the bike home and will keep you all posted! Thank you for all of your help IT IS APPRECIATED!!!!! Any other thoughts and suggestions are still welcomed.

 

Wow, compression tester only costs about $30 at an auto parts store. I mean, the good ones are a lot more,but oh well, he needed to go anyway. Do the hair dryer thing, and PM me if you need any help.

 

Also with the bike idleing,spray some WD-40 around intake area gaskets and see if idle changes any.May also have a intake leak.