Educate me

[bikerphil]

The 79SF have richer (less holes) emultion tubes in cyl 2 & 3 but all the main jet sizes are the same across the board. that's how it came stock. Now my 79F has all 4 emulsion tubes the same and all same main jets also. Mind you these are the early type carbs.

[mack]

Thanx guy's

The reason I asked these questions was that while at the bike show last Saturday, I had lunch with Phil. In the conversation, he was telling me that he had a set of carbs that no one could tune properly. His bike (an H I think he said) was like a wet sponge until 4 K, then would run ok. Several people had cleaned them and tried to tune them but it made no difference. He eventually just put out a few hundred and replaced them and now they are hanging on someones wall. It's been in the back of my mind ever since, and I've been playing different scenario's through my head, but the carbs I've done were all for specials. Now after this thread, I have a better idea of what should be in there. I'm going to ask him to retieve the carbs and send them down to me so I can have a look at them. Shame to waste them when it's probably something simple like wrong tube/jet needle combo's or undersized mains even.

[XS1100_OEM4ME]

Thanks Phil

Thanks Phil, that is what I thought and I know my carbs are stock. I am trying to learn as much as posable about these bikes and the diff in years / models for swaping parts if needed as many are hard to find now It is confusing when I get info from others that doesn't match what I know is OEM on my bike, so thanks for confirming that my carbs are correct

The 79SF have richer (less holes) emultion tubes in cyl 2 & 3 but all the main jet sizes are the same across the board. that's how it came stock. Now my 79F has all 4 emulsion tubes the same and all same main jets also. Mind you these are the early type carbs.

[ViperRon]

1980 Standard

I have a 1980 standard G model the original had 2 and 3 as a 120 and 1 and 4 as 115 main jet original and with stock airfilter pipes always run hot. With carb's clean as a pin float levels all set perfect it blued the pipes down arround to the connection point and the plugs were bright white like new. I have changed my jets to 122.5 all four and now have plugs running tan and the bike appears to run well. Personally I do not think there is a performance gain in getting a motor running as lean as possible infact I think it decreases life of the engine.

[XS1100_OEM4ME]

Fuel

This kinda makes me think that the changes in gas over the years has had a big impact on how these old carbs work. I know back when I bought my 1st Special and knew others that had them also back in 1979, the pipes didnt blue, you didn't have to clean the carbs every few months and almost never needed adjusted I road mine for years without ever doing anything to the carbs

I have a 1980 standard G model the original had 2 and 3 as a 120 and 1 and 4 as 115 main jet original and with stock airfilter pipes always run hot. With carb's clean as a pin float levels all set perfect it blued the pipes down arround to the connection point and the plugs were bright white like new. I have changed my jets to 122.5 all four and now have plugs running tan and the bike appears to run well. Personally I do not think there is a performance gain in getting a motor running as lean as possible infact I think it decreases life of the engine.

[ViperRon]

gas

I can not speak for others but for my bike the pipes always turned blue and the plugs were white. This is the first and only change to the carbs since it was new. Gas has changed and with the prices the way they are I sometimes think the trucks deliver a little water with it. If I see a delivery truck at a station I do not get gas there as deliverys stir the watter and trash up. I can tell you that gas that sits more than a month starts to deteriorate and leave it 6 months and you might be having to clean things out it was not that way 20 years ago.

[mack]

Carbs

I 've been experimenting with my sf carbs and plug gap's since I got it back on the road. It runs like a charm but my plugs look brand new. I showed them to a guy at a performance shop and he said the motor looks like it's tuned perfectly. I'm skeptical as I'd like to see a little tan colour, so as soon as the LH is back together, I'm going to pull the sf carbs and move the c-clips to one position richer and start the process with gapping plugs again.

[crazy steve]

...I'm skeptical as I'd like to see a little tan colour...

Remember, with modern unleaded fuel a clean, white plug is normal. Leaded fuel would quickly give you that tan color, not so anymore.

[XS1100_OEM4ME]

Blue

Did your pipes turn blue because the new OEM carbs wern't working right, or because you ran the piss out of it Any chrome pipe will blue if you heat it up enough with hard running of the motor But back in the day, my carbs never even needed adjusted, much less rebuilt

I can not speak for others but for my bike the pipes always turned blue and the plugs were white. This is the first and only change to the carbs since it was new. Gas has changed and with the prices the way they are I sometimes think the trucks deliver a little water with it. If I see a delivery truck at a station I do not get gas there as deliverys stir the watter and trash up. I can tell you that gas that sits more than a month starts to deteriorate and leave it 6 months and you might be having to clean things out it was not that way 20 years ago.

[bikerphil]

I had lunch with Phil. In the conversation, he was telling me that he had a set of carbs that no one could tune properly. His bike (an H I think he said) was like a wet sponge until 4 K, then would run ok. Several people had cleaned them and tried to tune them but it made no difference.

I worked on those (Maximphil's) carbs up at Marty's in Georgia and the one thing I noticed was the needle jets and emulsion tubes were brand new, leading me to believe that they were replaced with the wrong ones.

I'm going to pull the sf carbs and move the c-clips to one position richer and start the process with gapping plugs again.

JMHO, I would start with richening the float levels before messing with the needle clip. Nine times out of ten it will run best with it in the center. That clip position for the most part only affects the transition between pilot and main circuits.

Wish you luck with your carb nightmares.

[3Phase]

... They all let the bike pull good, and run up to red line.

Don, Columbo needs a lot more fuel than 110 or 112.5 mains can provide to waft along gently and comfortably in magic carpet mode on a hot summer day[1] in the desert but I know Steppenwolf has been running his dressed SG for decades so it can be done. I'm assuming that he's still using the stock jetting but I could be wildly and colorfully... wrong.

With all of those different carburetors you tried, what kind of time did it require for your Special to run up to red line in 5th gear and did you ride more than a few minutes or a 1/4 mile?


1. Void where prohibited by law or common sense and especially Canada or any other location where a 25C (77 in old money) summer day is routinely considered too hot to be outdoors riding a fully loaded motorcycle with the proper gear.

[mack]

carbs

I worked on those (Maximphil's) carbs up at Marty's in Georgia and the one thing I noticed was the needle jets and emulsion tubes were brand new, leading me to believe that they were replaced with the wrong ones


Bikerphil
Thats exactly what I wanted to look at.

Steve
I may get a scope and look at my piston crowns. I just don't want to be running too lean and burn a hole. It has a slight vibration at 5500 rpm, not a knock or ping but a slight vibration. Thought it might be lean. No dead spots though from 1-8.5 K off a line.

[mack]

Scott

I set all my bowls individually with a line hooked up to the bottom of a bowl I've rigged. They all sit at the top of the washer level. A long arduous process but still easier than installing and removing the carbs repeatedly.

[XS1100_OEM4ME]

What washer

I set all my bowls individually with a line hooked up to the bottom of a bowl I've rigged. They all sit at the top of the washer level. A long arduous process but still easier than installing and removing the carbs repeatedly.

[MaximPhil]

The reason I asked these questions was that while at the bike show last Saturday, I had lunch with Phil. In the conversation, he was telling me that he had a set of carbs that no one could tune properly. His bike (an H I think he said) was like a wet sponge until 4 K, then would run ok. Several people had cleaned them and tried to tune them but it made no difference. He eventually just put out a few hundred and replaced them and now they are hanging on someones wall. It's been in the back of my mind ever since, and I've been playing different scenario's through my head, but the carbs I've done were all for specials. Now after this thread, I have a better idea of what should be in there. I'm going to ask him to retieve the carbs and send them down to me so I can have a look at them. Shame to waste them when it's probably something simple like wrong tube/jet needle combo's or undersized mains even.

Hi Mack,
While those carbs came off an 81H we do not know if they were original or even a matched set. The decision to use the "new" carb set was based on the fact that a) they were working on a Special and b) the old ones were not working after several attempts and were consuming gas as though it were FREE c) XSEast2011 was over 800 miles away. d) My hobby is riding not fixing motorcycles

25 plus % improvement in fuel consumption convinced me I do not want to go back

Phil