Carbs out of sync

[pshaw]

I have an 81 MNS and the carbs are out of sync. When I started it up for the first time it idled fine until it warmed up, then the rpm jumped to 5K. I took the carbs off and tried to presync them using the bread tie method. The gap is less than the thickness because I couldn't get the butterfylies to open any more...but I adjusted them with an equal small gap. I started the bike, #2 coughs a bit and the others are fine. Once warm, #2 still coughs but the idle is around 1K. If I throttle it it stalls. Where do I start with the "fine" tuning? thanks.

[red bandit]

Hi, it sounds like you need to clean em.

[skids]

You couldn't get the butterflies to open any more? Start with the No.3 carb and use the idle speed knob for that opening adjustment and adjust the linkages so that the other 3 will match that opening.

[TopCatGr58]

Hey PShaw,

RedBandit is probably right in that wondering if you've properly cleaned them?? If it stalls when trying to apply throttle, something besides SYNCH is amiss! Are your vacuum slides moving freely, are there any holes in the rubber diaphragms of the slides? All sorts of things could be wrong, ALONG with the synch!
T.C.

[pshaw]

I've cleaned the carb twice. When I start to make the adjustments with #3, where should the main idle be set? I unscrewed it all the way until it wasn't making contact. And then when I thought they were adjusted I screwed it in 1 turn after contact.

[skids]

We are talking about synch and not idle mixture screws, right? If you are doing the synch-by-wire thing (aka"bread tie"), you don't worry about setting idle rpms until you are all done synching. Yeah, you might have to open butterflies 1, 2, and 4 a little just to get No. 3 perfect with the idle knob. You screw the idle knob clockwise (if looking at the face of the knob) to open that butterfly). When she is all finished, then you can start it with the choke lever pulled out and adjust idle rpms after the bike is sufficiently warmed-up with the choke lever pushed all the way in. If you are getting a fuel-fouled plug, you might want to consider adjusting the idle mixture screw inward. The header pipes should get hot at the same time if you can keep the bike idling with the throttle on a warm start.

Originally posted by pshaw
I've cleaned the carb twice. When I start to make the adjustments with #3, where should the main idle be set? I unscrewed it all the way until it wasn't making contact. And then when I thought they were adjusted I screwed it in 1 turn after contact.

[pshaw]

I've been screwing in and out the three screws on top between the each carb (three of them) and the main idle screw below. Where are the idle mixture screws?

[TopCatGr58]

Hey PShaw,

Seeing that you have an 81MNS, then the idle/pilot screws are under little brass caps sealed at the factory, they are on top of the carbs, next to the portion that fits into the intake mounts. You need to gently drill out those caps with a bit just big enough to fit a sheet metal screw a few turns into them. Then you can use a locking pliers and hammer to loosen and tap them out. Be careful, the pilot screws are just about 1/4" below the top, they are only about 1/8" to 3/16" thick so drill slowly so that you can feel it when the drill bit breaks thru so you can stop and keep the drill bit from drilling out the slot of the pilot screw that sits beneath.

Then, there are several metal and rubber O-rings that are below the screws, so be careful when you unscrew them so as to not loose those parts, some like to get stuck down in the hole!

IF you haven't pulled them out, then you can't really be sure of getting the pilot circuit clean which affects how it idles as well as the roll on low rpm throttle response!
T.C.

[CUBuffs]

Things that make you go Hmmm!

If you are getting a fuel-fouled plug, you might want to consider adjusting the idle mixture screw inward.

IF you haven't pulled them out, then you can't really be sure of getting the pilot circuit clean which affects how it idles as well as the roll on low rpm throttle response!

Sounds a bit like what's happening with my SG "Money Pit". Plugs 1,2 & 4 look good but #3 looks sooty. So according to Skids I should turn the idle mixture screw clockwise a little bit?

Also on low RPM, when just starting to roll my "Money Pit" (SWMBO thinks I should just go buy a new Roadliner ) seems to stumble/hesitate; and that could be related to the idle mixture screw?

Sorry PShaw, don't mean to hijack your post.

[skids]

Re: Things that make you go Hmmm!

There could be other reasons for a sooty plug. Here are all of the things that come to mind:

If the fuel level in that bowl is too high,

if that butterfly plate is open too far relative to the others (carb synch),

if the air passage to the idle jet is plugged (will draw to much fuel), or, if the "pilot air jet" is restricted, or,

if the starter jet (aka choke) set screw has come loose for that carb.

Originally posted by CUBuffs

Sounds a bit like what's happening with my SG "Money Pit". Plugs 1,2 & 4 look good but #3 looks sooty. So according to Skids I should turn the idle mixture screw clockwise a little bit?

Also on low RPM, when just starting to roll my "Money Pit" (SWMBO thinks I should just go buy a new Roadliner ) seems to stumble/hesitate; and that could be related to the idle mixture screw?

[CUBuffs]

Hey Skids,

I know that the pilot jet is clear because I cleaned the carbs thoroughly just before Spring.

However, I have not completed a carb sync because I don't have the merc stick or gauges, but yesterday I found the "bread tie" method in the tips section so I will try that.

Would you recommend adjusting the idle screw for #3 first?