Funky Idle on 1979 Cb750

weaseltree19

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Hey all,

So I've got myself a 1979 cb750k. Back when I didn't know much about the cb series, I put pods on the bike. Didnt really make any attempt to rejet. Now that I'm older and wiser, I've pulled the pods and put the stock airbox back on. I just started it up and synched the carbs. When I got on and took it for a spin, it was accelerating REALLY slow, even with the throttle full open.

I pulled out all my air mixture screws about 2 turns which did help a little bit, but didn't help with my other problem, which is the fact that I cant hold an idle at 1100. Its odd, Ill adjust the idle to around 1100, and then it sputters and dies, but if I tweak the idle screw up barely at all, the idle jumps to around 3000. Even with the idle set at around 1100, ill give it gas, and the idle will jump up to 3000ish and wont come down for a while. Every couple of seconds, I'll hear an extra combustion from the engine as well.

We we've got;
Slow acceleration
Possible extra combustion/out of time ignition from one of the cylinders
Funky idle, wont hold at 1100, but easily jumps up to around 3000, no middle ground.

I have synced the carbs. I imagine that this may have something to do with timing?

What do y'all think?
 
Idle leaping wildly high is commonly a vacuum leak, it leaps when you add fuel to cover the air leak. Until then too lean to run. As in..........

'Ill adjust the idle to around 1100, and then it sputters and dies, but if I tweak the idle screw up barely at all, the idle jumps to around 3000.'


Has anybody ever run a compression test yet? I say because if it's off nothing you do will make it run 100% right until that is remedied.
 
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