BigT

What 1460 says. You get the adjuster screws close by doing a bench sync. If the carbs are still on the bike, just tweak until they're even

1. Clean the carbs -http://members.dslextreme.com/users/bikecliff/images/vm_carb_rebuild.pdf 2. adjust the valves 3. Bench sync the carbs 4. Set fuel screws at 7/8 turn out, air screws at 1 1/2 5. install carbs 6. tune to high idle with air screws 7. Vacuum sync the carbs- they should be close from the bench sync. adjust any carb Your syncing at 2,000 rpm is correct. Opening the air screws made the idle mixture leaner, is that what you wanted to do? and, why? If it won't idle, your idle circuits are plugged

How low of an idle are you talking about? Idle should be 1,100-1,200 rpm for VM carbs

Yep, Kawasaki carbs or a mongrel. Suzuki carbs would have the pilot fuel screw underneath, a plastic covered lever on the choke and the vacuum port on #3. Does that jet really say Solex 145? Solex? I have no idea how that converts to Mikuni. Buy some Mikuni 125 main jets and see if it runs better

Um, you know they made two more generations of GS 750s, from 1980 on, right? Apparently not

Are the MJ 145 Mikuni? Because that would be really rich. Should be around 125. But, are they Dynojet MJ? Since the carbs aren't stock, some pictures might help

The high compression is not causing your starting issue My 78 1000 has the WISECO 1085 kit with 10.25:1 compression and it starts just fine As Blubber says above, maybe the carb bowls aren't filling? The VM carbs are notorious for evaporating the float bowls empty. Have you tried setting the fuel tap on Prime for 30 seconds prior to starting?

According to some GS racers I know, the small port head (78-79) provides better port velocity and cylinder filling. this gives a broader powerband. this will match better with the smooth bore 29s The large port head would be better for peak horsepower, with large carbs, if you were drag racing, or a totally built race motor, like for the Phillip Island Classic

http://members.dslextreme.com/users/bikecliff/images/vm_carb_rebuild.pdf This is how to clean VM carbs If you short cut this, you're taking the long road Cleaning the carb body is the most important part, followed by making sure the pilot fuel screw tips aren't broken off and still in the body

Based on those results, your idle circuits are clogged I didn't look back, did you strip, dip* and new O ring the carbs? Or, ultrasound

I'd pull off the ignition cover and try to start it in a dark shop. See if the points are sparking. Easy to get bad condensors these days. Also, I'd check voltage to the coils, especially when cranking

You're going about it all wrong. Set the fuel screw at 1 turn. Then, starting at 1 1/2 on the air, open it up a 1/4 turn at a time to achieve high idle on each carb. Remember, these only control idle and just off idle. Your issue appears to be fueling on start up. VMs are known to evaporate fuel faster than other designs. Have you tried putting the fuel cock on Prime for about 15-20 seconds prior to starting?

What are the pilot air and pilot fuel screws set at? No one's mentioned the pilot fuel screws. Pull the carbs and remove the pilot fuel screws. Are the holes open in the carb bodies, or are the tips broken off in the carb bodies? Reinstall the pilot fuel screws and set to one turn out. Set pilot air screws to 1 1/2 turns Check the pods and make sure they're not blocking the air jets in the carb mouth

I see where you're coming from, but, I don't see someone swapping the 3 carb parts, the triple, the triple cap, the cable, and the triple cover to a 79 spec, just for the choke, when just leaving the choke lever on the carbs would not require all that Plus, who would swap the foot pegs?

EBC makes great organic brake pads, I've been using them for years. They also have semi metallic pads No disc wear issues noted in 42 years

Interesting, but wrong. 78 has fluted tank/tail with stripe, black airbox, round passenger pegs and choke lever on the carbs. Yours may have been manufactured in late 78, but it's a 79. Picture of my 78 that I bought new. It's the wire wheel version, which I understand is not common in the UK

First, that bike is a 79, not a 78 (not that there is much difference for what you want to do) Here's a link for carb cleaning, service manual, etc http://members.dslextreme.com/users/bikecliff/ If you don't want to swap suspension and wheels right away, do the Salty_Monk Twinpot upgrade, cause old brakes suck Definitely swap out points ignition for electronic, I've been running the Dyna S since 1983. Engine upgrades are good, I've been happy with a 1085 Wiseco for years, otherwise it' stock

Probably the oval O rings for the oil feed

Suzuki still carries a lot of parts for the GS. I thought someone inn the UK made SS brake pistons? Google the Salty_Monk Twinpot Upgrade

Also, there are O rings under the float needle seat, which are prone to failure Replace all of the O rings in your carbs CycleOrings.com

CycleOrings.com for the O rings It's a bit hard to tell, but are you confusing the pilot jet with the pilot screw? The pilot jet is what you're showing in the pics, they need to have the rubber caps over them The pilot screws are on the top front of the carbs

With pods and 4-1, set the fuel screw one turn out from lightly seated and the air screw around 2 turns Tune the idle with the air screw Fresh O rings are very helpful

SO, did you replace all of the O rings in your carbs Because the one on the mixture screw could be causing your problems

https://www.gofastinnovations.com/store1/ https://www.amazon.com/TEKTON-2910-2-Inch-Manual-7-Piece/dp/B000NPUJYE/ref=asc_df_B000NPUJYE/?tag=hyprod-20&linkCode=df0&hvadid=309802506143&hvpos=&hvnetw=g&hvrand=8074902996176511159&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9032917&hvtargid=pla-384324752796&psc=1 If you're going to work on old bikes, you need some proper tools. You can likely find something similar closer to you.

http://zeus.mtsac.edu/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf CycleOrings.com If those O rings crumbled, imagine what the other O rings look like after 35 years If you haven't taken the carb rack completely apart, you haven't cleaned the carbs