Topic: Why would my bike stall when revved with a loose oil cap?

[SKTP]

So I just rebuilt my engine. And when starting it up for the second time after adding more oil, you know how you have to run it a bit to circulate it to fit the last 0.5L in....I overlooked tightening the oil-cap/dip-stick (in my excitement? I don't know how I would overlook that. But I did)...so then, the next time I started it it ran normally but would bog when revved...I initially thought I must have the timing off and was about to look into that when my girlfriend noticed the cap was not tight. We tighten the cap and the bike now runs amazing...Why is this the case?

[Jimray23]

My guess is its a fluke and the problem will probably show up again sooner or later. Can you make it happen by just loosening the oil cap?

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Jim
1979 kz1000b ltd
    stage 3 cams
    pod air filters
    4-1 open exhaust(no muffler)
    full rewire
    dyna-s ignition
    dyna 3 ohm coils

[flybox1]

+1
Most likely unrelated to what is really going on, but dont tell her that 

[PeWe]

Oil cap not tightened will allow better crank case breathing?
Crank case breather hose is connected to oil tank, right? Oil tank is closed, no ventilation as the older oil tanks?

[SKTP]

I really need to run the bike more...I've only had time to run it twice after finally getting it back together. The first time, it started right up (see the INSTA link if you like)...it idled well, but would bog, then stall when given throttle....I have only set the timing visually by the marks at this point. Going to static time it this weekend. It is a 78K and the oil-tank breather is connected to the case.

The second time I ran it...it did the same; good idle, bog on throttle...then we tightened the oil cap...and BOOM! Runs liek a champ!

VERY FIRST START AFTER TOP END REBUILD https://www.instagram.com/p/BUstRXaltdO/?taken-by=harvisbarvis

[flybox1]

SK...have you run it long enough for an idle plug chop?  How do they look?

It'll start even easier with 1-2 full, brisk throttle twists BEFORE you pull the choke.  Get those accel pumps working for you 

[SKTP]

I've barely run it. All I do is work. It's been running for maybe 5 minutes total. I always hear people say "plug chop" debut I don't really understand what that is? Is it outlined in the manuals or the Hondaman book? I'll try twists as you suggest. Thanks


EDIT: googled. No, I've never done this.
http://www.braigasen.com/howtoread.htm

[flybox1]

The idle plug chop is helpful in that it gives you a visual reading (combustion deposits on the plug insulator) for idle air/fuel mixture(lean/rich), so that you can more accurately adjust your PD carbs fuel screws (IMS - Idle Mixture Screws).

Once your IMS, fast idle cam, and accel pump are all working in unison, cold starts are effortless.

[SKTP]

I have never played with my carbs much. I guess it is time. I'm also thinking staic timing should be helpful.

[flybox1]

I have never played with my carbs much. I guess it is time. Well..yeah!    I'm also thinking staic timing should be helpful.

Are they at least clean?  Accel pumps squirting in all 4?  Fast idle cam lifting slides?  Clear tubed fuel levels?
Yeah...now that its running get all that good bike-lovin', tuneup stuff done, including a vacuum sync to top it off.
Then..dial in your IMS

[SKTP]

They are clean and bench sync'd. I sent them to James Hale.

[emlupi]

Then..dial in your IMS
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What is the process for dialing in the IMS?