Red Loctite on fuel mixture screws.

[KEITH KRAUSE]

Suzuki, or maybe Mikuni, applied paint over the top of the pilot screws on VM carbs. Commonly visible on the air screws. It doesn't lock the screws in place, but it certainly makes removing them more difficult than otherwise would be the case.

Yes, I knew about the factory applied sealant on the CV's mixture screws and the VM's pilot fuel and side air screws. It was applied to try to stop emissions tampering. It sure made a lot of owners frustrated over the years.

[Chris Bock]

I’ve set the fuel mixture screws at 2 turns out. That’s just for preliminary work for getting the carbs adjusted. I have a CarbTune Pro, and set the #2 & #3 butterfly’s at 5 cmHg marks below the outer cylinders. I haven’t tuned carbs on a bike with a stock airbox setup before, but the shop guide says that is the correct balance. Still getting some popping during deceleration. I’m getting a ColorTune soon, and will dial in the mix screws. Should I balance the carbs evenly? Or follow the shop guide recommendation? I can mess around, and find out. But any insight beforehand is appreciated

[mustangflyr]

Prior to the last rebuild of my carbs I purchased a bottoming tap to make sure the threads for the mixture screws were good to go. Use a M6X.5 bottom tap.

[Chris Bock]

Good call. If there’s still gunk at the bottom of the threads, that could give a false seating for the mixture screws.
Still waiting for the ColorTune to come in, and looking forward to try it out.
Plugs look decent now, maybe a little lean, though.
Unfortunately, it looks like I have a blown seal or gasket, though.
Gray/white smoke from the exhaust. Not a lot, and it decreases when revving. Any thoughts from the community?
Not looking forward to pulling the head, but I might as well replace the valve seals, and lap them.

[KEITH KRAUSE]

I'd balance the carbs per the factory recommendations, as you said you did.
As for the exhaust smoke, did you do any other work besides the carbs? How many miles on the motor and has it been sitting long or had a history of infrequent use?
The valve stem seals get hard over time. Also, the more the bike sits between runs, the harder the seals become. If it smokes more at cold start up and the smoking decreases as the motor warms up then that suggests worn seals.
This happened to my '79 GS1000 over time. I decided on seals from APE. They claim they won't harden like the stock seals do. Rapidray, a member here, suggested them too. I also decided on having him service the head while installing the seals. Saved me some money compared to having APE do the work. I don't know if APE sells seals for your model. I bought mine in 2018 for about $80 for the set.
Just be sure your oil level isn't high first.

[Chris Bock]

Running pretty good now! No more white wispy smoke. I live in Seattle, so there's plenty of steep hills to put load on the engine. May have been buildup in the cylinders, or stuck rings, or the carb dip residue I didn't get blown out. Finally had some decent weather to get to open her up WOT. And presto! No more smoke! Carb settings sound great, but I just received my Gunson ColorTune today, so I'm looking forward to playing around with it, in conjunction with the Morgan CarbTune Pro.
Any ColorTune advice for working on CV carbs is appreciated.
One final note: the PO had removed the baffles from the stock 4-2 megaphone pipes. I picked up some cheep inserts (which sounded horrendous!) When I was engine braking down a hill, I heard two Loud AF backfires which killed the engine! Pulled and released the clutch to get running again. Sounded way deeper after. At the bottom of the hill, found out those two backfires had launched the cheapo aftermarket baffles out!
Though it does sound burly as heck, I'm not interested in straight pipes.
Can't find any NOS baffles online for it. Anybody have recommendations for replacements? 1980 GS1000G. They're the stock megaphones. Not the reverse? megaphones that tapered at the end.
Thanks!

[dorkburger]

Baffles can only be removed from stock pipes by drilling / cutting / permanently damaging them so you're looking at replacement.

[Chris Bock]

These aren't them, but they're the same type. The megaphones with the exposed baffle. Not the fully enclosed pipes. They have screws/rivets keeping the end plate in. So they are removable. I just need to find something to fit back in there
28BFABF4-52B0-4444-A421-8D2803521343.jpg

[phydeauxmutt]

I have a CarbTune Pro, and set the #2 & #3 butterfly’s at 5 cmHg marks below the outer cylinders. I haven’t tuned carbs on a bike with a stock airbox setup before, but the shop guide says that is the correct balance.

What "shop guide" were you using? The Suzuki manual shows the official gauge, which is a set with four balls. The marks are un-numbered, but the recommendation is to set the inner two cylinders 1/2 ball lower than the outer cylinders. Someone here did a comparison some time ago and found that 1/2 a ball was about 2 cm.

Any ColorTune advice for working on CV carbs is appreciated.

All I can say is "good luck". Most members that have tried a ColorTune on CV carbs have been disappointed. I have tried it myself, and agree. The color never changes. As you lean the mixture screws, you will see the flame start to sputter, then become more intermittent, then finally die out. As you richen the screw, you will see the flame sputter back to life and eventually get steady. I would go with the leanest setting that gives you a steady flame.

One final note: the PO had removed the baffles from the stock 4-2 megaphone pipes. ...
Can't find any NOS baffles online for it. Anybody have recommendations for replacements? 1980 GS1000G. They're the stock megaphones. Not the reverse? megaphones that tapered at the end.
Thanks!

As someone already mentioned, there is no such thing as a replacement NOS baffle. Although it LOOKS like rivets holding the baffles in, there are also spot welds. There is simply no way to replace just the baffles, unless you get lucky looking through a catalog for Kerker, Supertrapp, V&H, MAC, etc.

[Chris Bock]

Drats! Thanks for the reply. I have a set of stock 4-2's from a free parts bike, but they have the crappy "header" spray paint flaking off of the chrome. Gonna try to get them back to chrome.
I did try the ColorTune. It actually worked as claimed! I'm not sure what setup was used with unsuccessful attempts, but I found that plugging the vacuum tube from the carbs and using an external tank worked great. Shout-out to Andy's Motorcycle Obsessions for plugging the vacuum tube with CV's!
And the CarbTune wasn't in the shop manual, it was in the Clymer Guide.
But, yes, the two outer are about half a "ball" (mine has slugs instead of balls) about 2cm (not 5) higher than the inner cylinders.
Thanks, all!