Motorcycle problems 1971 Honda CL70

[Dioxin01]

Hey everyone! So I've been working on a little 1971 Honda CL70 for almost a year now and can't seem to get it running right. Its newest problem is backfiring. If you apply the throttle more than halfway then it's like you're standing in the middle of the O.K. Corral. The ignition coil is brand new, as is the battery. It has a new spark plug which it doesn't seem to like (the bike won't start with the new plug, only the plug from 30 years ago and yes, they are the same model). I'm thinking it's a carb problem. I've spent so much time trying to get that damn thing adjusted right that I think maybe the best option is just to buy a new carb.

[Johnj]

Ok...First things first. Have you adjusted the valves? With the engine COLD remove the valve caps (2) and the spark plug. Turn the engine over SLOWLY while watching the intake valve, it will open then start to close. When it closes completely (TDC) you should have free-play on both valves. Your clearance is 0.05mm (0.002 in) for both valves.
Next is your point gap should be set. Turn the engine over observing the points through the cutout in the rotor until they are open to their maximum gap. The gap should be 0.3-0.4 mm (.012-.016 in). Then hook your ohmmeter to the engine case and the other to the black wire from the points. The points should begin to open when the "F" mark on the rotor aligns with the stationary timing mark.

All adjustments must be made before you continue.

Hello and welcome to the forum.

[Dioxin01]

Ok, thanks! And do I still need to adjust the valves even if I have never touched them and know that the previous owner hasn't either?

[Johnj]

YES

[Dioxin01]

Ok so the valve clearance was a bit too small, that has been fixed. However, like most inexperienced mechanics, I make mistakes. I overtightened one of the valve covers (or tappet cap I believe it's called). Do you know of any site I can buy one from? Ebay only has one person selling as a "buy it now" and they are from Taiwan. It says shipping could take 7-32 days and I can't wait that long. I also need a flywheel puller, I can only find steering wheel and gear pullers which I know could damage it.

[Johnj]

Have you tried your local Honda dealer. You'd be surprised at what they have laying around.

[hondafreak]

hey i know i little about your honda your spark plug problem might just be the fact the gap is to wide tap it down a little with cloth over it and your carb you might just want to buy a new one cause the holes at the end of the jet will get pitted and the fuel can expand and warp everything


p.s. im looking for a wiring harness for my 1971 cl70