Topic: I touched the air screws and now it won't start

[Lupo_00]

Hey guys,

I got a barn find 750K1 frame with a K3 engine. First thing I did was clean up the carbs, then broke a jet off in one of them and replaced it (temporarily with a 76' 750F carb).  I did not touch the air screws.  After tracking down some air gaps in wiring it started right up idling at around 3100rpm (jets are 40 and 110, exhaust is just 4 pipes no muffler. I read hondaman's chapter on carbs, so now I'm a pro (hah). Figured to get the idle to 1100 or so, I'd screw the air screws all the way in and then back out 1 1/4 turns, start there and adjust accordingly doing a full sync down the road. It won't start. Tried adjusting out a quarter turn at a time and restart, but still nothing.  And of course I didn't take note of the air screw setting prior to adjusting it.  Thoughts?

[Bankerdanny]

You are wasting time messing with the carbs without the exhaust in place unless you intend to run open pipes (and really, don't do that). Also, do you have the stock airbox and filter, pods or nothing at all?

You need the intake and exhaust set up the way you plan to run them, the points set and timing correct,  the plugs clean and gapped, and the valves properly set before you try to dial in the carbs.

[Lupo_00]

You are wasting time messing with the carbs without the exhaust in place unless you intend to run open pipes (and really, don't do that). Also, do you have the stock airbox and filter, pods or nothing at all?

You need the intake and exhaust set up the way you plan to run them, the points set and timing correct,  the plugs clean and gapped, and the valves properly set before you try to dial in the carbs.

Fair enough. I did do more electrical work than i said. I replaced:

Plugs
Wires
Coils
Starter Solenoid
Regulator/rectifier with a combo
Condensers
Rebuilt Handlebar switch (RH)

No airbox or pods when it was running.

Was hoping to run it to change the oil and filter. I'm just baffled at how it started up fine and now won't start at all.  I'll work on the exhaust and try again, though I'm not trying to fine tune the carbs yet anyway.

[ekpent]

 Base setting for the air screws are one turn out. There is a large knurled screw head under the carb bank on the side that you use to raise and lower the slide arms thus changing the idle. Even without any air filter and 4 open pipes your bike should still be able to start and run,maybe not great but done it many times while bringing them back to life. May want to check the basics like am I getting spark and am I getting fuel and work from there.

[Bankerdanny]

Does it try to start or does it just turn over without any hint of combustion? If it is the latter it doesn't seem likely to me that the air screws are the issue, more like an odd coincidence.

Not to insult you, but did you double check that the stop/run switch is in the middle "run" position? I have bumped mine accidentally to "stop" and not realized it. Also check where the wires from the points plug into the wiring harness. That is by the carbs and you could have knocked them loose (done that too).

[PeWe]

Fuel?
Maybe time for reserve position aiming backwards or a refill.

[Lupo_00]

I mean, I’m not saying it was fuel or the stop/run switch but I gave it more fuel and made sure the switch was in the right position and it started.... I feel like a college intern.

Thanks for the help guys.

[Lupo_00]

Also the bike idles a lot better without chocolate milk for oil.

[PeWe]

If it will run for 5-10 minutes and stop. Open tank cap and see if it will start again. Cap has a ventilation to let air enter tank so fuel can flow out.

[Lupo_00]

It had to have been the fuel level which was very very very low (a trickle left). Didn’t even think to look until you guys mentioned it.