New member here from Canada, recent rider and owner of a 1983 GS400E

[Mat]

only downside is they are not cheap on gas for their size.

Marc

I averaged more than 5L/100km so I agree with you on that

My first guess per your high idle would be that you are not allowing bike to warm up before taking choke/enricher off The second guess would be idle passage and jets..Do test for idle mix with warmed up bike and idle setting lower than you have it, then after noting where the adjusting screw are now, adjust them in and out and you SHOULD hear a difference in idle. (Two cylinder bikes are very simple in this way) If not, put a cleanout on your tasklist...I DID have to clean the "E"'s carbs intensively.In every old bike I've bought (9 out of 10) the idle jets are dirty with old gas. I only buy cheap bikes though.

I don't know if I'm doing this right but here is how it goes when I start the bike on a cold morning:
1- Full choke, push start, motor starts instantly whatever the temperature (...I'm always impressed)
2- Wait for the motor to rev up (usually goes up to 3000rpm after 20-30 seconds or so) and then adjust back the choke a little so it idle around 1300 rpm
3- I wait until it revs up again and repeat the process (2 or 3 more times) until it idle without any choke. I think all that takes a good 8 minutes or more and feels forever to me.

Is it how it's done? I once did let the bike run on full choke at 3000rpm but my girl asked why I was cutting grass at 6 in the morning

 

[argonsagas]

A small hint for fuel system maintenance:

Pour a couple of ounces of fuel injection cleaner into the gas tank. .
Run the bike until fuel level is down to quarter-tank before refilling.

Apparently the chemical composition is different from other gas additives, and does not harm carburetor seals.
I have been using it in bikes and cars for years with no problems.

 

[Gorminrider]

Yes, injection cleaner is something my local pro mechanic offers people first, when they show up with indefinite running issues...he says it often works, and I can see where it might help...the higher cost brand name gasolines might have similar additives. I know the Chevron High octanes polish the plugs up so maybe they rinse the jets a little too.

Yes, Mat- very similar to my 400s...I turn mine down very soon after starting-the bike won't actually move well with full choke! -and take off in about 30 seconds even if I need nurse the throttle a little to the first stop sign a few hundred yards on. Some leave it partly on but I tend to forget..
.. because it's common a warmed up bike idles smoother and higher than a cold one. Even fuel-injection adjusts to temperature... Unless the tach is faulty (but they usually fail as reading too low) I judge yours is idling too fast because YOU think so-it's really intuitive whatever the tach says...

 

[Mat]

Hey I just wanted to finish this tread with a big thanks to you all, I got my bike running well to my taste for now (I fiddled again with the idle screw, simple as that), thanks to you all for sharing experiences.

Going to enjoy the few weeks left of riding with more confidence I can get this bike top-notch this winter.

I guess I'll be more active in the forums when I'll get into maintenance early next year, until then, happy riding!

P.S. I've been using sea foam in the gas tank when I first got the bike and on first oil change.