Only runs with choke

[tcarr]

Okay, I got the idle adjustment screw problem fixed, and everything was peachy until I did a carb sync. When I synced the carbs (they were pretty far off) it raised my idle speed so much that when I have the idle speed screw out all the way I'm idling at about 3000 rpms. I'm guessing that means the adjustment screws on the carbs are off... even though I have them set to what was recommended here. (3/4ths turn out on fuel screws on bottom and 1 1/2 turns out on the air screws on top) are those the right settings for the VM carbs?

[Big T]

The fuel and air screw setting from Steve are correct

It is possible that you overadjusted your sync - try taking them down (clockwise) a 1/2 turn each and see what happens

[Steve]

Thank you so much Steve, wish I knew a way to repay you.

Now that you mention it, there is a way to repay.

Get your bike running correctly, get some pictures of it and post them here.

Okay, I got the idle adjustment screw problem fixed, and everything was peachy until I did a carb sync. When I synced the carbs (they were pretty far off) it raised my idle speed so much that when I have the idle speed screw out all the way I'm idling at about 3000 rpms. I'm guessing that means the adjustment screws on the carbs are off... even though I have them set to what was recommended here. (3/4ths turn out on fuel screws on bottom and 1 1/2 turns out on the air screws on top) are those the right settings for the VM carbs?

Those are the correct setting for where to start with the VM carbs. Once the bike is warmed up, slowly turn each of the air screws (the ones on the sides), listening for highest idle speed.

Your high idle speed might be because there is not enough slack in the throttle cable. Try loosening the cable at the carb mount or at the handgrip to see if that helps.

.

[tcarr]

I finally took some time tonight to take another look at it. And of course I have more questions... you all must hate me by now

When I began syncing the carbs my #3 carb was about at half the vacuum of the other 3. So on final adjustment three of the carbs had the adjustment screws out rather far, while I had to turn the adjustment for #3 in (down) quite a way. As it is now #3's adjustment screw has the keeper nut almost level with the bottom of the screwdriver slot, and the other 3 there are about 4mm of clearance.

Not sure I explained that very well, if you need I can post pictures of it. The only thing that seems different about that carb (other than that adjustment) is the float looks better than the others - the others look somewhat discolored while that one looks like it may have been replaced at some point.

I checked the throttle cable and that seems to be strange too. I can't feel any slack at the hand grip but I can see slack in the cable where it connects to the carburetor (on both cables) when I'm idling high I can twist the throttle forward and lower the speed so long as I apply a slight pressure to it, but it doesn't seem to be putting any pressure on the throttle at the carbs in it's resting position.

[BigD_83]

When you did your bench synch do you recall if the adjuster screw contacted the plate at all?

Is there enough room for you to capture a decent picture of this setup in the bike?

[tcarr]

Okay, apparently I didn't explain that well at all... My idle adjustment screw is fine now.

Below are two pictures of my carburetors: the first is of the adjustment screw on carb #3 and the second is where the sync screws are at on the other 3 carbs. This is after I did my on bike sync. Any ideas why #3 is so low? or why numbers 1, 2, and 4 are so high?



One last question: when assembling the carburetors will the needles on the slides (#23 on Steve's diagram) line up easily with the holes they go into or do they require you to put your finger in there and line them up? When I was assembling them I had to push the needle towards the rear of the bike to get it to go into the hole on several of the carbs (can't remember which ones - could have been all of them), could that be my problem?

[hampshirehog]

Below are two pictures of my carburetors: the first is of the adjustment screw on carb #3 and the second is where the sync screws are at on the other 3 carbs. This is after I did my on bike sync. Any ideas why #3 is so low? or why numbers 1, 2, and 4 are so high?

Throttle rod badly made or round the wrong way? Or air leak when you did the synch. Brain fade - I think you can get the rods round the wrong way (rotated). You can on some bikes but I might be making that up on your bike - blowed if I can remember for sure. Anyway, I would say it is unusual to have such a difference in screw height.

One last question: when assembling the carburetors will the needles on the slides (#23 on Steve's diagram) line up easily with the holes they go into or do they require you to put your finger in there and line them up? When I was assembling them I had to push the needle towards the rear of the bike to get it to go into the hole on several of the carbs (can't remember which ones - could have been all of them), could that be my problem?

As long as it was just a gentle guide and not forcing things straight then that is common - not a problem.

[tcarr]

Checked throttle rod, seems there's only one way it can go, but I'll take a peek again.

I went ahead and took the carburetors off again (since I'm finally getting good at it ) And looking down the throats they look horribly off for a bench sync (pics of #3 and other's averages below - hard to tell in the pics but there is a visible difference)




It seems I've read somewhere that you can't sync the carbs if your valve clearances are off, so I went ahead and checked them, cylinder #3 is the only one that is okay, 1 and 4 are off on the intake side and #2 is off on the exhaust side. Could that be my problem?

One more question about the valve clearances: what is the best way to get shims? Can I order a kit with a variety of sizes? The only kits I've found online are for really small shims, these seem to be around 30mm. Is there a good source for them?

One last question: I know this thread is technically still about my choke problem which has been seemingly solved. Should I start a more general project thread or do we keep going here?

Thanks guys!

[BassCliff]

Hi,

Check the GS Parts and Services section and learn about the Shim Club.

Or figure out what shims you need and order them from Z1 for $5.64 each.

Read this: Valve Adjustments (8 Valve)

For good measure, READ ME .

Thank you for your indulgence,

BassCliff

[keman]

Shim club for the win! Just did a trade for four shims. Shipping was fast. I sent him a some shims back, plus a few stamps..

[tcarr]

Things I've learned during my first 3 months with a GS550

Well, I think I have it all running well - as far as the carburetors - maybe a little fine tuning but I rode it 92 miles today and almost everything was peachy. After a long part of the ride I stopped for a few minutes and when I started it back up my oil pressure light came on - it didn't go out until I had it back on the road for a couple of minutes, so that's the next project I guess.
Below are some things I've learned from my first 3 months with my '77 GS550, thought I'd share them - even though everyone here already knows it all.

1. You can have the most perfectly clean carburetors, but you won't get anywhere without new o-rings.
2. If it has an o-ring, replace it. (especially on the intake boots)
3. The vacuum line to the petcock has to be plugged to sync the carburetors - even though the Hanes manual doesn't mention it. (also, read the forums and BassCliff's site - best place to find instructions.)
4. Always assume the previous owner did absolutely no maintenance and that if you haven't checked it, it's probably got something wrong with it.
5. Get an impact driver (either manual or powered) you can give yourself more headaches than a drunken sailor trying to use easy-outs or drilling out your bolts. I could have paid for my impact driver with the money I spent on broken easy-outs.
6. Never give up - there will be times when you want to take a cutting torch to your bike and build a piece of art out of it. But nothing is beyond saving if you work at it.

[Steve]

#4 is probably your best-learned lesson.

.

[ScrumDown]

You forgot an important one.

7. Take your time (and money, if need be) and do it right the first time. No need to half-ass it. You will regret it.



(Not that I have every half-assed anything before ... )