Another carb question, an intro, and pics!

[JerseyJon]

Hey folks, so here are the symptoms of my 80sg:

1. It's hard to start when cold. I have to hold the choke lever down to keep it shut tight, and then I run the starter forever trying to get it to fire. It seems that the combination of some spark/combustion plus the impetus of the starter can finally get it going. Just last night I discovered that slowly opening the throttle and holding it open as I hit the starter seems to make it easier. There is no problem starting when warm.

2. It idles very slowly after starting (say 700 rpm), and warming it up takes a long time, and it's hard to keep it from stalling out. I messed with the idle screw (that's that knurled screw that you can reach by sticking your hand under the carbs and adjust by hand, right?)

3. Once it's warm, and I've had it out on the highway, it idles very fast. So when I pull into a redlight, I look down and the engine is buzzing at around 2500 rpms. I can slow this idle down by just releasing the clutch a little and bumping the engine against the weight of the bike, maybe even keeping the bike stationary with the rear brake. When I release the clutch, it idles at a more appropriate 1100 rpms or so. (vacuum advance issue?)

4. Out on the road, the bike runs pretty good to my estimation. I mean, it seems to have power at both ends of the spectrum. I don't think I've taken it much past 90mph, but I've had it to 6000 rpms, maybe 7000, and it has power from 1000 to 7000.

5. There's this rubber tube that's off the bike. It's twisty, 12" long or so, has spring clamps on either end, and is about 1/2" in diameter. I don't know where it goes. I think one end goes into the transmission. Where does the other end go? Is this a vacuum advance thing?

So I've been studying this site like nobody's business. I have carbstix (motion pro), but I don't have a colortune thing. I like working on bikes, but I hate taking them apart and not being able to get them back together, and that happens to me. At first I wanted to re-jet the thing, and put in pods, but I've changed my mind based on what I've read here. The bike has less than 7000 miles, and it looks very stock, so why mess that up?

Here she is.

[JerseyJon]

Pictures, take two

So apparently I screwed up the picture thing. It worked when I posted in the bike photo thread. But maybe this will work:

http://s1240.photobucket.com/albums/gg491/jerseyjon4/

[CatatonicBug]

1. The choke is actually an enrichener. It adds fuel to the mix, rather than cutting the air supply. The choke lever should stay put. There is a detent ball in the carbs that gives you 3 positions: Full choke (all the way out), half choke (halfway in), and no choke (all the way in). Pull it all the way out and leave it there while starting, and until mostly warmed up. Then, bump it in after 1/2 mile or so of riding. Bumb it the rest of the way in before you hit the highway so you can open her up!

5. That's the Crankcase vent tube. It attaches to the top of the engine, under the airbox, then runs to the port on the front/center of the airbox to recycle the engine fumes.

VERY NICE bike BTW! Here's the picture:

[JerseyJon]

Yes, that's

the picture. I constantly overwhelmed here by how much I have to learn.

[natemoen]

I would say 2 and 3 are both sync and tuning issues.

[motoman]

I would say 2 and 3 are both sync and tuning issues.

Agree with Nate 100%!..........reachin in and messin with those idle mix's is why its gotchu where your at. That's TOO nice of a scoot by the pics to have any serious issues, other than the 'fiddleing' thats got it where it's at now. Bein' a Special, the 'octy' makes it a bit of a pain, but your gonna have to remove the seat and tank and either flip tank around on seat area or use another fuel soure and re-set idle mix on all four and re-sync for starters. Bettin that fixes its ill starting. Going to have to eliminate that as an issue before going any further. Cold with enricher pulled, or normal operating temp, with carbs CORRECTLY adjusted, starts with NO throttle roll-on, and should do it almost instantly.

[fredintoon]

Hey folks, so here are the symptoms of my 80sg:

1. It's hard to start when cold. I have to hold the choke lever down to keep it shut tight, and then I run the starter forever trying to get it to fire. It seems that the combination of some spark/combustion plus the impetus of the starter can finally get it going. Just last night I discovered that slowly opening the throttle and holding it open as I hit the starter seems to make it easier. There is no problem starting when warm.

2. It idles very slowly after starting (say 700 rpm), and warming it up takes a long time, and it's hard to keep it from stalling out. I messed with the idle screw (that's that knurled screw that you can reach by sticking your hand under the carbs and adjust by hand, right?)

3. Once it's warm, and I've had it out on the highway, it idles very fast. So when I pull into a redlight, I look down and the engine is buzzing at around 2500 rpms. I can slow this idle down by just releasing the clutch a little and bumping the engine against the weight of the bike, maybe even keeping the bike stationary with the rear brake. When I release the clutch, it idles at a more appropriate 1100 rpms or so. (vacuum advance issue?)

4. Out on the road, the bike runs pretty good to my estimation. I mean, it seems to have power at both ends of the spectrum. I don't think I've taken it much past 90mph, but I've had it to 6000 rpms, maybe 7000, and it has power from 1000 to 7000.

5. There's this rubber tube that's off the bike. It's twisty, 12" long or so, has spring clamps on either end, and is about 1/2" in diameter. I don't know where it goes. I think one end goes into the transmission. Where does the other end go? Is this a vacuum advance thing?

So I've been studying this site like nobody's business. I have carbstix (motion pro), but I don't have a colortune thing. I like working on bikes, but I hate taking them apart and not being able to get them back together, and that happens to me. At first I wanted to re-jet the thing, and put in pods, but I've changed my mind based on what I've read here. The bike has less than 7000 miles, and it looks very stock, so why mess that up?

Here she is.

Hi Jon,
the choke (it's actually an enrichener) lever should pull out to first one then another click.
If it don't click and it snaps back by itself when you let go the arm, some dreaded PO has lost the little balls and springs that make the click happen.
It could also be that having set the throttle stop so that it'll start stone cold with no enrichening and run at 700 rpm that way will make it idle at 2,500 rpm when it's warmed up

[JerseyJon]

thanks again

Fred,

The "choke" (enricher) lever stays where it's supposed to be. It's just that the bike stalls unless I press down on it pretty hard with my thumb.

Oh, here's something -- I get horrible mileage. The fuel light comes on at around 80 miles after a fillup.

I kind of knew that I needed to do some carb tuning. I'm not bad at this stuff; just a little rusty. I thinking of taking her out for a weekend trip. If I can get the carbs right before that, cool. If not, that's ok too. Once warm she runs really well.

[CatatonicBug]

Oh, here's something -- I get horrible mileage. The fuel light comes on at around 80 miles after a fillup.

That's just about right on a Special, especially with around-town riding. After you get it tuned properly, you might see it jump up to 85 miles before the light comes on. Do the math on the miles per gallon, and you should see somewhere in the mid to upper 30s. I've gotten as high as 44mpg once, and that was a long, liesurely group ride that stuck right at 55mph the whole time, and it was right after I installed the dynajet kit. Now, with regular riding, I get about 35-38mpg.