Topic: 75K 750 carbs, pods and 4-1, idling problems

[rbmgf7]

I know there are many here running emgo pods and a 4-1 exhaust. I'm just wondering what everyone is using for their carb settings. I've jumped between numerious configurations and i think i've narrowed it down to what works best without running rich or too lean.

mains:120 (i actually have 115. it has trouble past 6.5K and according to the throttle position chart, bigger mains are needed for that range)
slow:40
pilot: 1.5
clip: 4th from top

However, the bike has a horrible time trying to start and idle. choke doesn't seem to work. when i start a cold engine, i put the choke on and the bike may give me a putter once in a while. then i have to help with the throttle. once it catches on, the idle sounds horrible. if i throttle too much with choke, the bike will start to oscillate strokes like a high performance rotary engine. i can turn the choke off and the bike will idle better but won't stay alive without my help. basically i have to hold the throttle at 1/8 turn until the bike warms up enought to sustain on its own.

what's odd, when i got the engine, the PO was running a staight exhaust (no baffles, silencers, etc) but i don't know what he was uning for the intake. when i first ran the engine, the choke would work and it ran fine in neutral but the bike couldn't pull anthing. i'd throttle and it would die. at that time, the carbs were running at factory specifications and parts (105 mains, 40 slows, middle clip pos., 1.5 turns out)

i don't know much about cabs but the only thing i can think of is when it was running 105, the hole/needle-setting was small enought to prevent a pressure leak through the mains, so it would draw from the slows like it's suppose to at idle. but when i went to 115 (that's a tenth of a millimeter larger from 105, isn't it?), the main allowed a pressure leak large enough to bypass the slows. then it probably runs too rich to give a stoich combustion. i just can't see how such a tiny difference can make a big difference. so, i guess to sorta answer my own question, should i drop the needles to the second clip from the top to close that main jet orifice?

[joeb]

Did you clean out the carbs, also check for vacuam leaks.   

[TwoTired]

Your carb don't have an accelerator pump.
When you open the slides, the carb throat vacuum drops and stops pulling fuel from the jets untill RPM pick up and venturi effect once agin starts pulling from the jets.
The stock carbs overcome this by running very rich at idle... With the stock air box restriction.
You put on pods and this drops the suction while on idle and it draws less fuel from the idle jets, making it lean.  When you crack open the slides the engine starves for fuel.

You may be able to compensate by turning your idle air bleed screws in.  However, if they are hollow tipped type, they have limited adjustment range.  If you can't get your throttle response back, with the idle screws, You may have to go with a larger slow jet.

Also, you have larger mains but, you dropped your needles making midrange mixtures even leaner.  The mains feed the slide needle orifice. This can also have an impact on throttle response, and seems counter to compensating for the vacuum loss due to pod filters.  Less vacuum usually means larger orifices to compensate.

Also, you should examine your spark plugs to see what they tell you about combustion mixtures.

Cheers,