Rough idle, sluggish acceleration, and dying out

[Cajun Cruiser]

Hello all, been a while since I was on here, been busy finishing school. While riding my '76 several weeks ago, I noticed when I let off the throttle between shifts it seemed like a near total loss of power was occurring. At one point, it died a split second before I released the clutch and fired up when the gear engaged. When I got to the stop light and pulled the clutch, it went dead and almost didn't start again. I finally got it started and it's been running rough ever since. By rough I mean, I'll start it and it runs fine for about 10-12 seconds and then idles down and dies. I've adjusted the idle screw and got it to stay running and after a few seconds it'll idle up to 3k-4k RPMs. Adjust the set screw down, it idles down and dies. I've drained the tank, changed the fuel filter, and added ethanol free gas. To boot, in all my tinkering it seems like the fuel dissipates way faster than it should, and it seemed like I was getting poor fuel mileage before all this started. Some history on the bike, the guy I bought it from supposedly had the carbs. rebuilt but not synced. I synced the carbs. about two weeks before this issue started. Any help will be much appreciated!

 

[kerryb]

29 other people read this with no suggestions, so I’ll take a shot at it with a few scenarios. 1. Assuming you have s stock intake tract (filter box and four carbs) it sounds like your idle circuits are dirty/plugged because the engine dies when you close off the main jet (slides closed). When you increase the idle screw to get it to stay running, you are exposing the main jets. This can be a problem because now you are trying to fine tune with main & slides. That’s like trying to fill a teacup with a fire hose.

Yet another scenario is if you are running a single carb with no heat. When conditions are right, the carb freezes on a hot sunny afternoon, and the engine dies whenever the throttle is closed.
From the limited description here it seems you would benefit from a thorough carb cleaning with a full kit from Randakks (the most reliable parts kits) and a complete teardown and soak in carb dip. Get the instructions from randakks too and see the carb cleaning thread by roady (I thinks it’s on goldwingdocs.com). It’s not hard, but it does take patience and care to do it right.
Edit: a good writeup is by Octane on ngwclubforum. https://ngwclub.com/forum/viewtopic.php?t=2952. The book by Howard Halaz is from Randakks too and is very good.
Is your fuel system clean? A rusty tank may contribute to this.

 

[Cajun Cruiser]

29 other people read this with no suggestions, so I’ll take a shot at it with a few scenarios. 1. Assuming you have s stock intake tract (filter box and four carbs) it sounds like your idle circuits are dirty/plugged because the engine dies when you close off the main jet (slides closed). When you increase the idle screw to get it to stay running, you are exposing the main jets. This can be a problem because now you are trying to fine tune with main & slides. That’s like trying to fill a teacup with a fire hose.

Yet another scenario is if you are running a single carb with no heat. When conditions are right, the carb freezes on a hot sunny afternoon, and the engine dies whenever the throttle is closed.
From the limited description here it seems you would benefit from a thorough carb cleaning with a full kit from Randakks (the most reliable parts kits) and a complete teardown and soak in carb dip. Get the instructions from randakks too and see the carb cleaning thread by roady (I thinks it’s on goldwingdocs.com). It’s not hard, but it does take patience and care to do it right.
Edit: a good writeup is by Octane on ngwclubforum. https://ngwclub.com/forum/viewtopic.php?t=2952. The book by Howard Halaz is from Randakks too and is very good.
Is your fuel system clean? A rusty tank may contribute to this.

Thank you for the insight, I appreciate it! The previous owner communicated that everything on the bike except the fuel pump was original and the bike had sat in a garage for about 20 years. He claimed a carb. rebuild and a fuel tank cleaning but, looking in the tank based on your statement, there is some surface rust in some spots and the tubes in the tank are pretty well covered. I also remember reading on the Randakks blog that the rebuild procedure in some of the shop manuals aren't correct so that may be a factor as well. I think I will try at least a little Sea Foam over the next couple of days to get by but ultimately, I think I'll do a full tear down and cleaning as you have suggested. My idea of a rebuild vs. the previous owners idea are likely different, I'd rather have peace of mind knowing what I have. Thank you for the valuable input!

 

[dan filipi]

I've had on occasion needed to turn the gas off and let it run out of gas then turn gas back on. Seems to reset the floats where they need to be.

 

[Cajun Cruiser]

I've had on occasion needed to turn the gas off and let it run out of gas then turn gas back on. Seems to reset the floats where they need to be.

Interesting, I’ve not heard that before I’ll try that this afternoon. How long after running dry should I attempt to restart it?

 

[dan filipi]

It can be restarted right away after turning the petcock back on.

 

[Cobra 427 V8]

Hi I have a 76 , you can do some Idle circuit cleaning one carb at a time , get a heat gun and warm the elbow , and remove bolts of course , put a rag in the inlet port , now remove the mixture screw , and you will see a small brass elbow on one side of carb these come out and disconnect them from the hose , these need to be cleaned as there is a jet in the elbow , there is a randak mod to change the jet size , but anyway clean it , now get some brake clean or carb clean and squirt it down the mixture screw hole followed by 120psi of air , repeat x5 , if you look into the carb there is a little brass discharge nozzel make sure it is squirting out fluid, do one at a time then set screws to approx 3 turns out , sync , make sure you have good spark, have you lubed your advancer or checked the points/timing . I fitted a ignition relay to boost voltage to my ballast , and I removed the resistors in the replacement NGK plug boots with a bit of 4x17mm brass or similar, try all that hope this might help , also put a bigger fuel filter on it , don't use cheap Chinese lookalike gl1000 filters . Cheers

 

[MikeyG]

My 75 was doing that and all I did was add some sea foam and marvel mystery oil to the fuel and fun it a bet. Now, all is well.