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77 GS750 Pods with 4-1 pipes and a 21’ glass pack…
Issues:
1. #1 carb/pod backfires (chirps) after warmup on deceleration
2. white ‘vapor’ pours out of #1 carb after shut down (engine off)
3. Plug #1 very black and sooty – others are chocolate brown
I’ve done:
Quick compression test yields about 130psi on each cyl.
Valves adjusted
Carbs dipped and cleaning as per GSR
Needle position enrichened
New points and condensors
Static timed
Coils checked out good
New Plugs and plug caps
Good battery
This bike runs great but the backfiring out pipe and carb is a concern. I’m very experienced with 2 stroke motors. Not much with 4 strokes.
Do intake valves stick? Would the compression test rule out a bad valve?
Background:
This is my third GS resuscitation project… A 1977 GS750 I picked up for $100… The first 2 bikes I did were GS1000’s 79 & 80 both were free ‘just get ‘em out of here” The two 1000’s only needed the complete carb cleaning routine, valve adj., de-rust tanks and batteries. They are 100% stock and run great. The ‘77 however didn’t have carbs or an airbox or pipes – I have the correct carbs and did the dip routine, valve adj. and new points condensers and plug caps. Coil ohm test checks out fine. Seems to have great spark. Aquired a set of V&H Sidewinders with a Cherry Bomb glass pack and put pods on the carbs. I moved the needles to enrichen the ¼ to ¾ throttle range – I have not yet increased the main jet size yet (no full throttle runs yet) As indicated on this website I didn’t feel I’d have to change the pilot jets. The bike starts w/choke beautifully, once warmed up it runs strong and idles perfectly.
Thanks,
Ken
Issues:
1. #1 carb/pod backfires (chirps) after warmup on deceleration
2. white ‘vapor’ pours out of #1 carb after shut down (engine off)
3. Plug #1 very black and sooty – others are chocolate brown
I’ve done:
Quick compression test yields about 130psi on each cyl.
Valves adjusted
Carbs dipped and cleaning as per GSR
Needle position enrichened
New points and condensors
Static timed
Coils checked out good
New Plugs and plug caps
Good battery
This bike runs great but the backfiring out pipe and carb is a concern. I’m very experienced with 2 stroke motors. Not much with 4 strokes.
Do intake valves stick? Would the compression test rule out a bad valve?
Background:
This is my third GS resuscitation project… A 1977 GS750 I picked up for $100… The first 2 bikes I did were GS1000’s 79 & 80 both were free ‘just get ‘em out of here” The two 1000’s only needed the complete carb cleaning routine, valve adj., de-rust tanks and batteries. They are 100% stock and run great. The ‘77 however didn’t have carbs or an airbox or pipes – I have the correct carbs and did the dip routine, valve adj. and new points condensers and plug caps. Coil ohm test checks out fine. Seems to have great spark. Aquired a set of V&H Sidewinders with a Cherry Bomb glass pack and put pods on the carbs. I moved the needles to enrichen the ¼ to ¾ throttle range – I have not yet increased the main jet size yet (no full throttle runs yet) As indicated on this website I didn’t feel I’d have to change the pilot jets. The bike starts w/choke beautifully, once warmed up it runs strong and idles perfectly.
Thanks,
Ken
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