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Discussion Starter · #1 ·
My 73 CB350G is in great running order and a 100% reliable daily driver. However, I'm finding I have to gas it a little to keep it from dying at cold start, and it bothers me because when I first got the bike a few years ago it would idle cold with no problems at probably less than 1000 rpm. Now, if I start it cold and just let it be, it idles weakly and wants to die. The thing is, if I open the throttle a bit and rev it to 3-5k RPM once or twice, it starts idling fine and warms up normally. It's like I have to give it a little kick to get the gas flowing through the carb jets or something. And it only last for the first 10 or 20 second on cold starts and then idles fine. Choking doesn't help.

What are some things I can do to get it idling really smoothly on cold starts?

Things I've already gone through:
-valve clearances set
-spark plugs are clean and gapped, they're the NGK iridiums that are supposed to improve cold starts
-Timing is spot on with a charlie's place EI
-rebuilt carbs ~2 years ago as part of larger engine rebuild
-just ran through a tank with seafoam
-carbs are synced as best I can without a vacuum gauge (how do you actually sync these correctly by ear?)

Best I can guess is that I need to pull apart the carbs again and check for debris
 

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You want to be very careful gapping Iridiums, it is not usually done.
The iridiums are resistor plugs, did you change out the caps to be non resistor? If not you will have a weaker spark that will contribute to starting issues.
 

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Discussion Starter · #3 ·
When I put the iridiums in I did change the caps to what was labeled non-resistor caps (NGK-LZFH). However, looking at those caps again on the internet I'm finding a lot of conflicting information about whether they're resistor--- some listings clearly label them resistor and then some I found call them non-resistor. Mike's XS and several ebay listings call LZFH non-resistor, and then most other listings say they DO have a resistor. Even the box they came in doesn't say what they are. So this might be my problem, that's a good call.

Can you point me toward an NGK cap that is definitely non-resistor that works with the threaded plug terminals?

Listings are getting increasingly confusing--- I've now purchased 4 LZFH caps that seem to have different sub-model numbers on the box and cap, and the listing from where I bought each doesn't even mention those numbers. Are there different varieties of the LZFH cap?
 

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Discussion Starter · #5 ·
Thanks, this is great. It looks like LZFH is the only non-resistor cap but is universally mislabeled as a resistor cap on all the internet listings I've seen. So my current ignition setup is correct.

I think I may have found the problem though: my pilot screws backed out a little bit and I just re-set them. It seems to start up a lot better now.
 

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Next time you have the tank off check your voltage at the coils with the engine running. It should very closely match the running voltage at the battery. One of the first things I check on any of these bikes that comes into my garage, even ones I've checked previously.
Wiring in the headlight, kill switch ... a major resistance when dirty, key switch all need to be 100% clean and tight.
 
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