1978 GS550 all stock jetting to remove lean conditions

[prichmon]

Can anyone help me with suggested jetting for an all stock gs 550?

It seems to be very cold natured even on 80+*F days. It takes upwards of 5 minutes to warm up. When it's cold it has taken closer to 20 minutes for the carb bowls to get warm enough to take fuel. It also seems to be running lean on top. It acts like it is runnning out of fuel.

I am ~600' above sea level.

Thanks

[steveb922]

Have a look here:- http://gsarchive.bwringer.com/bikecl...at_height.html

[cowboyup3371]

What maintenance did you already do to the bike like carb cleaning and valve adjustments? Did you properly clean them using Nessism's procedures as posted on Basscliff's website - http://members.dslextreme.com/users/bikecliff/?

What jets are in there currently? Basscliff will have a document on his site that details the stock jetting sizes posted here - http://members.dslextreme.com/users/...eight.html#A01

[prichmon]

I had the Cleaned and rebuilt carbs by a old school tech with 25+ yrs. experience; upgraded to dyna s ignition, coils, wires with ngk boots and plugs in oem values. Stock jets. Stock airbox; uni oem replacement foam.

I have not done a valve adjustment.

[steveb922]

You'll be wanting to check your valves, and probably adjust them. Clearances tighten over time, and the only way to know you're good is to check.

Do you have the standard exhaust, and is there a fuel filter fitted, other than the one above the petcock (ie in the tank) and the small screens in the carbs?

[RichDesmond]

It's normal for bikes of that era to take a while to warm up, the low speed circuits are on the lean side. However, once warm it should run fine. If it doesn't, something is wrong and you should find and fix that problem rather than masking it with jetting changes.

[Big T]

What maintenance did you already do to the bike like carb cleaning and valve adjustments? Did you properly clean them using Nessism's procedures as posted on Basscliff's website - http://members.dslextreme.com/users/bikecliff/?

That's the wrong carb cleaning tutorial. Need to use the VM carb cleaning

[Big T]

Can anyone help me with suggested jetting for an all stock gs 550?

It seems to be very cold natured even on 80+*F days. It takes upwards of 5 minutes to warm up. When it's cold it has taken closer to 20 minutes for the carb bowls to get warm enough to take fuel. It also seems to be running lean on top. It acts like it is runnning out of fuel.

I am ~600' above sea level.

Thanks

Jetting is not your problem, unless your tech changed them. Your bike is set up lean, but should start immediately and warm up in a few minutes, regardless of ambient temperature.

Adjust your valves. Verify your ignition timing. If that doesn't work, time to clean the carbs (not the 1st person who needs to reclean the carbs)

[prichmon]

I had a 79 gs1000L; 81 gs1100e; gs750 many moons ago. I recall them starting with full choke; revving to 3500-4000 for ~ a minute. shut off choke and ride. Colder weather I had to choke for longer time.


I will clean cabs, check valve clearance and report back in a coupe weeks. I work out of town during the week.

[scratch]

Do you have a stock exhaust without leaks? That would also be helpful to know.

(Not that it precludes a valve adjustment, just useful info if trying to clear a lean condition... )

[prichmon]

It is stock with no mods. To my knowledge it is w/out leaks

[Steve]

I had a 79 gs1000L; 81 gs1100e; gs750 many moons ago. I recall them starting with full choke; revving to 3500-4000 for ~ a minute. shut off choke and ride. Colder weather I had to choke for longer time.

Wow, that scares me.

I would MUCH rather find the 'happy spot' where it takes the minimum amount of "choke" to start, then modulate the amount of "choke" to keep the engine speed below 2000. There is just something about a cold engine racing a 4000 that sends chills up my spine. It keeps the neighbors happier, too.

When everything is set up properly, I typically use about half "choke", get my helmet on and head out. Yes, that quickly. By the time I get on the road and into second or third gear, I will turn the "choke" off completely.

.

[jsandidge]

Wow, that scares me.

I would MUCH rather find the 'happy spot' where it takes the minimum amount of "choke" to start, then modulate the amount of "choke" to keep the engine speed below 2000. There is just something about a cold engine racing a 4000 that sends chills up my spine. It keeps the neighbors happier, too.

When everything is set up properly, I typically use about half "choke", get my helmet on and head out. Yes, that quickly. By the time I get on the road and into second or third gear, I will turn the "choke" off completely.

.

That's exactly the same procedure I use. Well, other than the extra 30 seconds or so it takes to put my gloves on.

[prichmon]

The issue is it won't take fuel. It warms up at 1500-2200. When I go to half choke it drops to ~750 and barely runs. If I attempt to give throttle ti dies.

[prichmon]

Found the carbs full of junk. Seems to have fixed the bike completely after a thorough cleaning, set to specs and repair of a drain tube.

Thanks guys