Mikuni Jet Issue ?

I beleive that they are all turned out 1 and 1/2 turns.

I think that is to far out, making it lean. Try setting at 3/4 turn and see how it does. In Rich, out Lean.

I didn't have much time to check on this, but I did start it up and set each air screw between 1/2 and 3/4 of a turn. The bike did ilde better. While check on this, I looked at the fuel in the see through filter and I was expecting the filter to be completely full of fuel, but it wasn't. When I turned the fuel off, the filer would fill up with the fuel that was in the hose connected to the tank. My question is, should the fuel filter be full of fuel when the bike is running ? I am hoping to have more time to work on this sometime this weekend.

The air screws on the 29s are different than on the other Mikuni carbs. On the 29s they have a small hole near the end that the other ones do not have. IMO I think a good starting point is to set them at 1/8 to 1/4 turn out from lightly seated.

Please note that I said that is a starting point and not the one and only setting.

When I get time again, I will start adjusting the air screws. Now I need to know about the fuel in the filter.

BIGKEVIN wrote: ...should the fuel filter be full of fuel when the bike is running ? ....

No, a clear inline fuel filter normally appears less than "full" when the engine is running.

Good Fortune!

BIGKEVIN wrote: When I get time again, I will start adjusting the air screws. Now I need to know about the fuel in the filter.

"No!" Patton addressed this...I run an EMGO large plastic/metal filter with 5/16 clear lines...Filter always appears to have air in the line...Dont trip because although you see air, you dont see the "volume of flow" of the fuel...Cheers Oh, one other thing...I have "Sudco/Mikuni" tuning manual that "advises against" trying to vacuum sync "VM" carbs because once the carb caps are removed while the engine is running, the TRUE vacuum signals are compromised...A good bench sync is all thats necessary for VM carbs. If your hell bent on vacuum syncing VM carbs...Smear the slides with "dielectric" or silicon grease to seal them against the carb/slide bodies to prevent a false vacuum signal reading. The reason your bike was high idling was because most 29mm smoothies have worn carb slides that leak vacuum when the caps are off.

zoro wrote:

BIGKEVIN wrote: When I get time again, I will start adjusting the air screws. Now I need to know about the fuel in the filter.

"No!" Patton addressed this already...I run an EMGO large plastic/metal filter with 5/16 clear lines...Filter always appears to have air in the line...Dont trip because although you see air, you dont see the "volume of flow" of the fuel...Cheers!... Oh, one other thing...I have a "Sudco/Mikuni" tuning manual that "advises against" trying to vacuum sync "VM" carbs because once the carb caps are removed while the engine is running, the TRUE vacuum signals are compromised...A good bench sync is all thats necessary for VM carbs. If your hell bent on vacuum syncing VM carbs...Smear the slides with "dielectric" or silicon grease to seal them against the carb/slide bodies to prevent a false vacuum signal reading. The reason your bike was high idling was because most 29mm smoothies have worn carb slides that leak vacuum when the caps are off.

Thanks for the replie Patton and Zoro. I did notice something else on the carbs last night that I need advice on. The part that the idle adjustment screw touches when it is turned in does not touch anything when the idle adjustment screw is completely removed. Should that part, which sets the idle, be making contact with something ? I have not been able to find the part names yet.

BIGKEVIN wrote: Thanks for the replie Patton and Zoro. I did notice something else on the carbs last night that I need advice on. The part that the idle adjustment screw touches when it is turned in does not touch anything when the idle adjustment screw is completely removed. Should that part, which sets the idle, be making contact with something ? I have not been able to find the part names yet.

If the end of the idle screw loses contact before sufficiently reducing rpm, it's likely that the bench sync was improperly performed.

When bench syncing, the idle screw must be set to where there's ample thread remaining to further lower the throttle slides from their bench-synced positions, as is usually required when later performing the actual engine-running sync.

Good Fortune!

I will take the carbs back off hopefully tomorrow. If there is already a gap between where the idle screw screws in and the part that moves to set the idle, wouldnt screwing the idle screw into the part cause the idle to be higher ? Does anyone have a diagram of the Mikuni 29 mm carbs with a parts breakdown so I can be more specific about the parts ?

BIGKEVIN wrote: I will take the carbs back off hopefully tomorrow. If there is already a gap between where the idle screw screws in and the part that moves to set the idle, wouldnt screwing the idle screw into the part cause the idle to be higher ? Does anyone have a diagram of the Mikuni 29 mm carbs with a parts breakdown so I can be more specific about the parts ?

If there is already a gap between where the idle screw screws in and the part that moves to set the idle, wouldnt screwing the idle screw into the part cause the idle to be higher ? --

No, because the individual throttle height adjustments are used to achieve bench sync.







Good Fortune!