Carb sync issues: Idle higher just to sync?

[davekat]

Hi folks,

So in this ongoing saga to get my bike working, I made the bottle sync tool, as prescribed, and finally, just focusing on two at a time, got carbs 1 and 2 to sync the best I could. First, I idled her with the idle screw to about 2000 rpm. Then I did 1 and 2, facing the same direction of the bike, starting from my left. Then I went to do 3 and 4. However, as I did this, in order to sync 3 and 4, that screw apparently made the idle go up to 4000 rpm! I thought, OK, maybe that's what it's supposed to do. So I go to do 1 and 3, with the throttle screw in the middle. However, that one is screwed ALL the way in, and the more I loosened it, the higher up the idle went. So I tried to lower it with the idle screw, and no dice. It didn't go.

And this is something I've noticed earlier when I was trying to control the idle. Between 3 and 4, the moment I started turning that screw in, the idle started to drop. So initially, besides trying the idle screw, which didn't do anything to drop the idle, I used the 3 and 4 to drop the idle down to 1500 rpm. However, after doing 1 and 2 (which were in balance after some work), when I checked 3 and 4, they were completely off balance, so as I balanced it, the bike went up to 4000 rpm, but carbs 3 and 4 were much more in balance (fluid wasn't shifting to one bottle as fast, and actually seemed to level out).

I then tried 1 and 3, and like I said, that screw (throttle screw) was turned all the way in tight. I had no choice but to loosen it, which only seemed to increase the rpm. I'm beginning to wonder if this might have something to do with my pilot screw? I double checked the screws during a reclean, and they were all set at 2.5 turns out (screwing them all the way in, and then loosening them 2.5 out)

Help?

[arsenic]

You are syncing the carbs the worst way in the history of forever. Two at a time with a homemade $1 sync tool. That homemade jobber may work for some folks, I'm calling BS on that. You want to do it correctly. I'd recommend buying a REAL manometer.

[davekat]

Well, I can at least get the 1 dollar tool to balance. I know it's not the best, but it's working. The problem I'm having is why is the rpm going up as I adjust the carb sync screw in the middle of 3 and 4, and as I'm trying to sync between 1 and 3. Nothing happens to the rpm when I synced 1 and 2. I initially set a baseline of about 2000 rpm.

[arsenic]

Well, no you can't. If the $1 sync tool got them too balance, the RPM's wouldn't jump. I really can't offer you any advice. Until you have the correct tool, there are so many things wrong. Also, 1750 RPM is the sync speed, not 2K. Not that I think that makes a difference.

[Wild-Bill]

I adjust 3&4 to each other, 1&2 to each other and then the two pairs to each other. One thing you may need to watch is that with the bottle sync tool you're not necessarily looking for the fluid to level out, you're looking for it to stop shifting. A better way to build the tool would be for both tubes to draw from the same reservoir. That way the difference between the two levels shows the difference in pressure between the two carbs.

If you've been messing with things a bit and not getting there it may be time to reset everything by pulling the carbs and bench-syncing them. With a good bench sync you shouldn't need more than about a half turn on any of the sync screws. If you need more than that then either your valves are off or you've got an intake leak.

[davekat]

OK, I think I've figured it out. Here's what I did. At the 4000 rpm level, I went ahead and balanced 3 and 4. Then I took a shot at 1 and 3, even though the high rpm was scaring me. Then I reset the idle screw, which, finally, the system starting responding to by lowering the idle. Whew! Good lord.

I then went and rebalanced 1 and 2, 3 and 4, and then 1 and 3. There's little to no shifting of fluid, and in some cases, it would seem to shift, and then on it's own, shift back to even?! I'm guessing that's OK. I hope.

SHE'S BALANCED! Sheesh this has been a long process.

Arsenic, a pro carb sync tool is definitely in the future for me. For now though, I hope/think she's rideable. Just have to put in new brake fluid, and change the oil and filter. She finally SOUNDS like a motorcycle should sound.

Thanks everyone!

[arsenic]

Congrats. BTW, you don't sync 1 to 3. You sync 2 to 3.

[davekat]

Congrats. BTW, you don't sync 1 to 3. You sync 2 to 3.

<Slaps Forehead>

Goddammitt...

[Wild-Bill]

If you're balancing 1&3 then you're dragging #2 along, too. Not anything you need to think about when you're looking at all 4 at the same time.

[davekat]

So for the first time ever, I decided to take her out for a spin. Took her out to a light industrial zone road, about a quarter mile from my house, thank god it's in my neighborhood, and and got her up to 45 on third gear. Near the end of the road, a mile and a half away, I shift down to first to do a u turn, and she shifts down, and dies.

Couldn't start her up again no matter what I tried, tried reserve tank, regular tank, shook the bike, heard a swishy sound, so that meant I had some gas. I figure, crap, it's the damn carbs again. I must still have a bit of bad gas in there or something (emptied out the tank of old gas (3 weeks old)) and filled her up with fresh gas.) So, I walk her back for a mile, thank god that was flat, to the big hill, where I prayed to the Gods to be merciful on me, and, strangely, she started up again.

She's back at my house, and let me guess the recommendation from you peeps.

Take the carbs out and clean em again for the umpteenth time? Mind you, they've been professionally cleaned, and I recleaned them again just to be sure before syncing them.
She does start up, but I don't want her die like that out on a busy road...

[Wild-Bill]

Dude, I feel for you. Where do you live? I'm across the river and a bit north of Philly, at the base. If you hit the maximum point of ****itivity then bring the bike to me and I'll help you get it going.

And, yes. the first step is to make ABSOLUTELY SURE those carbs are clean and adjusted right. Soak the bodies in Berryman's (12-24 hour soak for each one) and bench-sync before you install. Also, make sure your fuel line going to #1&2 carbs isn't too long. If that sucker is just a hair too long then it'll kink. Once it develops a kink you usually have to replace the line and try again.

[bluelinewall]

I know is may seem silly, but did you forget to hook up one of the fuel lines under the tank? I think there is two.

[davekat]

I know is may seem silly, but did you forget to hook up one of the fuel lines under the tank? I think there is two.

As far as I can tell, everything is properly connected. All fuel lines, air hoses, etc.

Dude, I feel for you. Where do you live? I'm across the river and a bit north of Philly, at the base. If you hit the maximum point of ****itivity then bring the bike to me and I'll help you get it going.

And, yes. the first step is to make ABSOLUTELY SURE those carbs are clean and adjusted right. Soak the bodies in Berryman's (12-24 hour soak for each one) and bench-sync before you install. Also, make sure your fuel line going to #1&2 carbs isn't too long. If that sucker is just a hair too long then it'll kink. Once it develops a kink you usually have to replace the line and try again.

if I reach that point, I might take you up on that offer. I have a buddy who actually works at the base, he's my neighbor too! He's also got a trailer, if necessary. But first I'm gonna run it through one more freaking time...

[Kreylyn]

You are syncing the carbs the worst way in the history of forever. Two at a time with a homemade $1 sync tool. That homemade jobber may work for some folks, I'm calling BS on that. You want to do it correctly. I'd recommend buying a REAL manometer.

I normally agree with Chris on most things carb related. This is not one of them.

My experaince has been that homemade sync tool is AT LEAST as accurate if not more so for a carb syn than any pro tool you wanna claim is the right tool.

So for the first time ever, I decided to take her out for a spin. Took her out to a light industrial zone road, about a quarter mile from my house, thank god it's in my neighborhood, and and got her up to 45 on third gear. Near the end of the road, a mile and a half away, I shift down to first to do a u turn, and she shifts down, and dies.

Couldn't start her up again no matter what I tried, tried reserve tank, regular tank, shook the bike, heard a swishy sound, so that meant I had some gas. I figure, crap, it's the damn carbs again. I must still have a bit of bad gas in there or something (emptied out the tank of old gas (3 weeks old)) and filled her up with fresh gas.) So, I walk her back for a mile, thank god that was flat, to the big hill, where I prayed to the Gods to be merciful on me, and, strangely, she started up again.

She's back at my house, and let me guess the recommendation from you peeps.

Take the carbs out and clean em again for the umpteenth time? Mind you, they've been professionally cleaned, and I recleaned them again just to be sure before syncing them.
She does start up, but I don't want her die like that out on a busy road...

Your have a flow issue of fuel to the carbs. I wouln't look at the carbs, I would look at the tank, petcock, and fuel lines (got fuel filters?) and so on making sure the fuel is flowing.

Use a container and check the petcock and fuel flow is working and flowing well.

Krey

[arsenic]

I normally agree with Chris on most things carb related. This is not one of them.

My experaince has been that homemade sync tool is AT LEAST as accurate if not more so for a carb syn than any pro tool you wanna claim is the right tool.

That's who I was referring too when I said "works for some folks".