A
Anonymous
Guest
Hi,
I recently managed to got an NEW set of vm 29 Smoothies at ebay (here in germany). Naturally they are some years old, but have been unused so far. They also have an accelerator pump assembly on them, which is rather unusual for these carbs. So, basically I?m a very lucky guy
).
I know for sure they aren't RS, stock VM or other carb types.
My bike is a stock '78 gs 1000, 100.000km, motor rebuild but with stock pistons (first oversize), stock airbox, stock exhaust. Just electronic ignition, new coils, oil cooler. Intake manifolds are new for i had to change them by size compared to the old VM26SS carbs. Bike ran ok with these old carbs, so ignition, valves and all that other stuff should be ok.
First i tried the carbs with some aftermarket pods (no K&N), but the performance at low and top end wasn't any good, the bike just sputtered around.
Then I went for the stock airbox, and the performance when opening the throttle is amazing, the plug readings are really optimal.
My problem is the idle circuit. Bike will start hard with yoke, you can set the yoke so that it runs ok on idling till its warm. When it is warming up, and you close the yoke, there is much stuttering, bike dies off etc. No popping, no backfiring thru exhaust.
When i remove the airbox cover, things just dont change. Spark plug readings just don't give any real hints, cause with pilot air screw out a half turn, they look good, out 1 1/2 turns, they look a bit lean, but not much. Things are a bit better when air screw is turned in to maximum (1/4 turn).
So i'm supposing that idle circuit is to lean and I have to richen it up. Am i right? Should I change the pilot jet? To what size? Is there anybody out there with the same configuration and a carb jetting that ist running well on idle?
Jetting now, like recommended and factory default for these carbs on gs1000 (according to mikuni/SUDCO manual), is:
Main 115
pilot jet 25
Jet needle 5dl31-3
Needle Jet O-6
Main Air Jet 0,9
Cutaway 2,0
ThanX a lot for any advises to the "old" continent
Michael
Germany
I recently managed to got an NEW set of vm 29 Smoothies at ebay (here in germany). Naturally they are some years old, but have been unused so far. They also have an accelerator pump assembly on them, which is rather unusual for these carbs. So, basically I?m a very lucky guy
).I know for sure they aren't RS, stock VM or other carb types.
My bike is a stock '78 gs 1000, 100.000km, motor rebuild but with stock pistons (first oversize), stock airbox, stock exhaust. Just electronic ignition, new coils, oil cooler. Intake manifolds are new for i had to change them by size compared to the old VM26SS carbs. Bike ran ok with these old carbs, so ignition, valves and all that other stuff should be ok.
First i tried the carbs with some aftermarket pods (no K&N), but the performance at low and top end wasn't any good, the bike just sputtered around.
Then I went for the stock airbox, and the performance when opening the throttle is amazing, the plug readings are really optimal.
My problem is the idle circuit. Bike will start hard with yoke, you can set the yoke so that it runs ok on idling till its warm. When it is warming up, and you close the yoke, there is much stuttering, bike dies off etc. No popping, no backfiring thru exhaust.
When i remove the airbox cover, things just dont change. Spark plug readings just don't give any real hints, cause with pilot air screw out a half turn, they look good, out 1 1/2 turns, they look a bit lean, but not much. Things are a bit better when air screw is turned in to maximum (1/4 turn).
So i'm supposing that idle circuit is to lean and I have to richen it up. Am i right? Should I change the pilot jet? To what size? Is there anybody out there with the same configuration and a carb jetting that ist running well on idle?
Jetting now, like recommended and factory default for these carbs on gs1000 (according to mikuni/SUDCO manual), is:
Main 115
pilot jet 25
Jet needle 5dl31-3
Needle Jet O-6
Main Air Jet 0,9
Cutaway 2,0
ThanX a lot for any advises to the "old" continent
Michael
Germany
