jetting opinion

[jetmechmarty]

The SF has different carburetors than my SG. Jetting is not the same.

[jjz28]

i thought all the carbs were the same as long as they were mikuni 2's.

[jetmechmarty]

I replaced the needles and seats. Does it matter which way the needles are oriented on the floats? My airbox is still filling up with fuel. I'm at a loss. Why can't I get this right?

If you're just tuning in, this is an on going issue for me.

[motoman]

Moto man


Main jet (115) 620 14231 23 A0 for G and SG

G and SG are both 1980 models just different jet size recomended as SG is 120 and 125 and G model is 115 and 120

May as well correct this before it gets "away"...............80-81 Special FACTORY main jets= 110's across.............80-81 Standard FACTORY mains 115's outside cyl.(1&4), 120's inside cyl. (2&3). 80-81Special had shorter quicker taper metering rods than the Standard. The longer rods/longer taper account for a bit leaner and not quite as snappy responding as the "bar-hoppin'" Special.

[motoman]

I replaced the needles and seats. Does it matter which way the needles are oriented on the floats? My airbox is still filling up with fuel. I'm at a loss. Why can't I get this right?

If you're just tuning in, this is an on going issue for me.

Bettin your floats are draggin' on the carb gaskit. Leave gaskets in place and with an exacto knife trim the sides of gaskets letting the inner bowl edge be the guide. No orientation of the needles is needed. BTW, floats may look like they clear, but when gasket is compressed, has to push out somwhere. On another note, if leaking into airbox, at least a small amout of fuel HAS run into cyls.and bled by rings and into oil. Do as you may, but even that minute contamination WILL reduce bearing(rod/mains) life enough to cause pre-mature failure down the road........when?....anyones guess and that left to chance would not be my choice.

[jetmechmarty]

Thank you, Motoman. I'll the trim today. I'll change the oil again as soon as I stop contaminating it.

Somewhere along the line, perhaps the jet needles were tampered with. I can't see how 110 across can work for me when I see a white plug running a 120 jet. I even replaced the butterfly seals.

[bikerphil]

I replaced the needles and seats. Does it matter which way the needles are oriented on the floats? My airbox is still filling up with fuel. I'm at a loss. Why can't I get this right?

If you're just tuning in, this is an on going issue for me.

Marty, I put those viton tip needles in so the wire is furthest on the float tang. As mentioned, trim down the sides of the gaskets a little and also adjust the float drop tang so the floats don't drop as far down. Check for side to side play on the floats. There is a way to tighten them up on the float pin if they are loose, but it is a delicate procedure. If you crimp them too far closed, you'll need a numbered drill bit set to correct them so they move freely. I usually close them up a little, then drill them out with the correct numbered drill bit. That way the clearance is perfect and less likely to bind. As you know, be careful of the delicate float posts.

[motoman]

I can't see how 110 across can work for me when I see a white plug running a 120 jet. I even replaced the butterfly seals.

Float levels affect the mixture ALOT. Just depends on where the RUNNING actual fuel levels are in the bowls. A half a millimeter can drasicly change the mixture.

[jetmechmarty]

Bikerphil,

I followed those instructions. I filled the carburetors before putting them back on the bike. I appear to be in business. I installed them and pushed the button. The bike started. No fire, no fuel in the airbox.

Motoman,

Since the floats are over thirty years old, do you think they may float lower, thus raising the fuel level? Raise the level to go rich, correct? I may have to revisit the float height, but in the meantime I'll have a look at the plugs with the new jets.

Thanx for the input, gentlemen.

[bikerphil]

Bikerphil,

I followed those instructions. I filled the carburetors before putting them back on the bike. I appear to be in business. I installed them and pushed the button. The bike started. No fire, no fuel in the airbox.

Well that's good news. As for the plug color, gray color is fine, that is how all of my plugs look. If you have new plugs in there, it may take a hundred or more miles to get a decent color on them. Open up your mixture screws a half turn or so if you still have whitish color plugs. If that doesn't help, then I'd raise the float level 1MM (lower number when carbs are upside down).

[jetmechmarty]

I was OK with gray. The middle ones are white. I already did the half turn thing. It stopped the loud exhaust popping on deceleration.

[motoman]

I was OK with gray. The middle ones are white. I already did the half turn thing. It stopped the loud exhaust popping on deceleration.

Sounds like you bout' got it.

[jjz28]

The same thing was happening to me. First it was one carb so i pulled it and cleaned the seat real good with a drimmel brush (with my fingers not in the drimmel), trimmed the gasket and put them back on. I set it to prime and cranked a little and then gas went everywhere, out the back of all and out the vent tubes with i have no lines on cause i am just testing it. I got rid of the octi. Well, i turned off the gas, cleaned it up and turned it back on for ****s and giggles and it doesnt leak anywhere now. I started it and no leaks at all. But, it takes throttle REALLY well until i try to take off on it, it seems to bog unless i rev it, once it gets up just a little it runs good. Could this be because i have no filters on it and its getting too much air? This is only in my yard for a test, i know i need the airbox and filter to ride it to protect the carbs. Thanks.

[motoman]

The same thing was happening to me. First it was one carb so i pulled it and cleaned the seat real good with a drimmel brush (with my fingers not in the drimmel), trimmed the gasket and put them back on. I set it to prime and cranked a little and then gas went everywhere, out the back of all and out the vent tubes with i have no lines on cause i am just testing it. I got rid of the octi. Well, i turned off the gas, cleaned it up and turned it back on for ****s and giggles and it doesnt leak anywhere now. I started it and no leaks at all. But, it takes throttle REALLY well until i try to take off on it, it seems to bog unless i rev it, once it gets up just a little it runs good. Could this be because i have no filters on it and its getting too much air? This is only in my yard for a test, i know i need the airbox and filter to ride it to protect the carbs. Thanks.

Hard to pin-point as there is a whole array of things goin on at this point. No air filter box, creating one. No idle mix set or carb sync, another. With all the other variables, at this point, IMO the idle circuit is too rich, either from high float levels or idle mix too rich. Goin to have to get carbs closer to correct before any pre-mature diagnosis.

[jjz28]

All i did was clean the carbs, i didnt change any settings and they were dead on before the bike sat. It revs really good, more like a crotch rocket than my xs750. I think it may be i dont have my filters on. I just got home from work and my caliper rebuild kits came in so i will fix them tommorrow and put the air box on and see what happens.