GS 550 running away

[Nessism]

Did you try backing out the idle stop screw?

[gs550rebuildguy]

yes backed out the idle

It will idle at 3800 not 5000 with the screws set at three h an half turns out

[tkent02]

Idle stop screw, the big one in the middle.

[gs550rebuildguy]

yes

Yeah made sure the idle stop is not pushing at all and lots of slack in the cable for choke and throttle thabks

[gs550rebuildguy]

so here it is

It idles good IF I unhook the vacuum on number two but that's because it goes cold
as soon as I plug the line its back to 5000 rpms at idle
Going to check clearance on valves tonight and recheck compression
I DO have another engine but I just need help finding my LEAK !!

SO going to get starting fluid to carefully spray around
new hose clamps
new o rings for carbs
new o rings for intake boots
soaked rebuilt SPOTLESS carbs
I may need luck of the irish to find my leaks
If its valves maybe I need to pull the heads if the clearance checks out right??

[Nessism]

The problem is not the valves, it's either a vacuum leak or the throttle linkage is hanging up somewhere.

If you take the carbs back off and look at the throttle butterflys, they should almost completely close if you back off the throttle stop screw. If they don't close like this, something is wrong with the throttle linkage. When you hook up the throttle cable make sure the cable ends are fully seated and there is slack in the cable - free play as they say in the manual. If the butterflys are closed, the bike won't idle. If it does, you have a vacuum leak somewhere for sure.

How about pulling the carbs back off and taking some photos showing us those butterflys. Post the photos on photobucket and then link the img code here. We need to see how you have things set up. Regarding vacuum leaks, using starter fluid is an unreliable method. It's been proven countless times before. It's much better to literally trace the intake path and make sure everything is properly sealed. No gaps between the boots and the carbs. Airbox installed, filter installed, airbox lid installed. Airbox fully sealed with foam for the filter and lid.

[Steve]

I know that you said you "Carefully Bench synced the butterfly valves", but did you ever do a VACUUM SYNC?

Even a "careful bench sync" is not perfect, it just gets you close enough to get the bike running to do the vacuum sync.

.

[gs550rebuildguy]

Valve update

I have not had it vacuum synced yet
I had some spare time and checked the valves
Four are flush NO gap and the remaining are borderline .03
So...
Thursday I plan to take em all back to .08 when my tool arrives
If it still runs bad I may pull the head to see if the prev owner burned some valves.
I should not be having consistent backfiring on number two where its easy to tell as I have a clear vacuum line that lights up from the flames
I put my hands on the other carbs and felt pulsations on number three and number one but two is the worst and that one had very tight valve clearances so once there back in spec I will see how it runs
For the bench sync I used a small wire starting with number three like the book says
They all WILL close if I back off the idle screw enough so for the prelim I left them at the wire setting gap and set rpms from there but as we know there is no setting the rpms on this demon yet and the throttle cable is NOT binding nor is the choke.
The CV's play well together also.
My money is on valves right now...
Thoughts??

[tkent02]

Once the valves are all in spec vacuum synch the carburetors.
Even if you had already done it, valve adjustments change synchronization.

[gs550rebuildguy]

question

Do you agree valves get tighter since its manly seat wear not cam wear?
Funny how the book covers "adding" thicker shims in the examples...
Do you have an easy way/trick to find if they are burned??
My guess is that if the valves cant close that would explain how it is possible to idle with the plates closed as it would be getting air on the downstroke like a "systemized" crower cam does on a Camaro with deliberate over lap for better mixing.

[tkent02]

Do you agree valves get tighter since its manly seat wear not cam wear?

Usually, but not always.

Do you have an easy way/trick to find if they are burned??

Check the compression.

[gs550rebuildguy]

I did a compression check and posted that before

I now have to tool to release the shims
Not sure where topdead center is on my dyna ignition but will learn that and recheck valve clearance as I was doing it with the lobes straight up (Clymer method)
compression was left to right 120, 120, 130, 150
4 intake was zero mm
3 exhaust was zero mm
2 exhaust was zero mm
1 intake was zero mm
the rest were .03 mm
Goal= .08 when Im done
If the compression dose not get better the "beatings shall continue until moral improves" lol
seriously I may pull the heads then and see if the valves are burned

[gs550rebuildguy]

Idle screw removal

Part of the battle was I got a 1/16th inch cobalt drill for a pilot hole and a 5/64 final I bought a 5/32 with no glasses on at the hardware store so my ten torx bit was not gonna work but my 25 cranked er right out of there however it broke the head off so I had to drill a 1/16 hole in a 5/64 hole
So with 1/64 room left to drill see the attached file
Perhaps this contributed to my higher idle but the new screw went in ok and it did not suck any WD40 down the hole when running so back to valves more tonight
I'm pretty proud of the attached pic though lol

[tkent02]

Part of the battle was I got a 1/16th inch cobalt drill for a pilot hole and a 5/64 final I bought a 5/32 with no glasses on at the hardware store so my ten torx bit was not gonna work but my 25 cranked er right out of there however it broke the head off so I had to drill a 1/16 hole in a 5/64 hole
So with 1/64 room left to drill see the attached file
Perhaps this contributed to my higher idle but the new screw went in ok and it did not suck any WD40 down the hole when running so back to valves more tonight
I'm pretty proud of the attached pic though lol

Wow, an easy out actually got something out. First time for everything I guess.

Don't be in a hurry to pull the head. Set the valves, if the comp doesn't come up ride it 1,000 miles or so. Ride it hard. Then check again.

[gs550rebuildguy]

Chain support question

Ok so I took the valve cover off my spare replacement engine and under the cam chain is a bridge looking piece to support the chain and MY current engine does not have it...possible the 1981 gs550 "T" does not use one there or maybe that's what my issue has been all along??
I will consult the manual this evening but was pretty surprised.
It is part of the cam chain tensioner??
Ps getting my last shim tonight and then going ridin