My shovel has new points and isgetting plenty of spark. The s&s carb is good. Everything is good and it should start but All it will do is backfire and sputter. It will not start !!! I have been arond bikes for years, I even tried holy water on this one. Any Ideas??????

c

 

Were you having troubles before you changed the points?

Did you change the condenser too? A bad/weak condensor will make spark but fall apart as rev's increase.I'm sure you gapped the points properly. Is your advance working freely? The advance springs and the flyweight pivots OK? Flyweights aren't dragging?

Is your fuel fresh? Might want to drain the carb bowl and tank if it's last years stuff.

 

Something to think about, I had changed the points and condenser on a sportster I had and it appeared to do the same thing as your talking about. After spending days messing with it I pulled the new points out and compared them to the old set and low and behold, the points spring was longer. Everytime the points would open the spring would short out and trigger the ignition. LOTS of sputtering and backfiring. Went and got another new set, good quality points this time, and she fired right off.

Other option is you didn't by chance move your timing plate, by accident of course?

 

How good was it running before the new points. Advance units do wear out.

 

It was running fine and the coil burnt out. I replaced it and no luck. oue of the springs was broke on the advance weights andI replaced it. new points & condenser and a good s&s carb. Valves are working fine. It just pops and backfires when I turn it over. Do you know any timing tricks ?? I cant think of any reason it wont start and run other than timing. I have tried numeros timing positions but no luck.

Thanks

Crapps

 

Since the coil crapped out and you replaced it, I assume with the proper coil, that of course, should no longer be the problem. Using your shop manual, (You do have a shop manual, don't you?), make sure the advance mechanism is installed and lubricated properly, intall and set the point gap then static time the engine using the method described in the book for the retarded timing setting. Make sure you are using the retarded timing mark on the flywheel. That will get you into the ballpark to get it started. If you don't have an ohm meter or static timing light, an old trick was to use the plastic wrapper from a pack of cigarettes in between the points. It's very thin plastic so when the points start to open just enough to pull the wrapper out fairly easily, you should be close enough. This works if the points are new (nice smooth contact surface), if they have started to get rough, dress them up until they are smooth again or, you can go with them a little rough if you think you have a "feel" for it considering that they are rough. If these new points are already looking kinda rough or burned, you probably have a bad condenser.
This should get the timing close enough to start the bike. Set the timing with a timing light at your earliest opportunity.
If the bike was running okay before the coil puked its cookies and you didn't mess with other stuff like the carb or valve adjustments, then your bike should start again.
I hope this helps you, good luck.

 

When you install the advance unit, make sure that goes on right, there is a pin on the advanve unit that has to line up with the points cam and you can get it 180 off. when you go to tighen up the bolt it will force the cam unit on but will not be lined up with the little pin. This is real easy to get it 180 out and cause all the backfiring.

 

Call me I'll walk you through timing etc typing is not my forte 608 847 4240

 

did you replace just one spring on the advance weights? you should replace them in pairs.

also they come in different pull strenghtths. check to be sure you got the correct ones.

if a spring broke check the screw that holds the weight assembly in and be sure it isn't bent.

also be sure they are snapping back before installing.

lastly you do know to advance the lobe when setting timing right.

let me know if i can help out.