1980 XS11G- Can't sync carbs

[jmailley]

I cleaned the carbs and reinstalled. ike was running a bit rough still so I tried to snyc the carbs. I got #1 to come into the normal range but 2 wouldn't move. Stayed on the low end (gauge says Intake leak at manifold). #3 & 4 wouldn't settle down enough. Needle jumping all over and wouldn't get into range. What could cause this? I will start over by checking the timing first, then compression? Doesn't look like the manifolds have any leaks but I will re-check. I put a new (used) CDI box on last year and it made a huge difference. Any suggestions would be great.

[BigRed]

Spray some WD-40 or Starter fluid on your intake manifolds while your engine is running (have a fire extinguisher handy just in case). If RPMs go up, you've got leaky intake boots. This will cause your bike to run crappy and lean. It'll also result in low vacuum. You can either seal up any cracks or replace your intake boots. I just got a set off eBay for under $100 this year.

[XSokieSPECIAL]

I cleaned the carbs and reinstalled. ike was running a bit rough still so I tried to snyc the carbs. I got #1 to come into the normal range but 2 wouldn't move. Stayed on the low end (gauge says Intake leak at manifold). #3 & 4 wouldn't settle down enough. Needle jumping all over and wouldn't get into range. What could cause this? I will start over by checking the timing first, then compression? Doesn't look like the manifolds have any leaks but I will re-check. I put a new (used) CDI box on last year and it made a huge difference. Any suggestions would be great.

Make sure the sync adusting screw setup isn't sticking between 1 & 2.

Do you have adjustable dampers in the lines for the guages?

Gotta have those there to settle down the vacuum fluctuation.

[randy]

Adjust your valves, adjust your cam chain, then synch.

Intake boot leaks at the head can be cured by using a gasket. I know they don't show one in the fiche, but i never install them without a gasket. You can cut your own, or there's a Ford thermostat gasket that fits, do a search here for the part number.

[jmailley]

Thanks guys. I'll try those things and get back to you.

[jmailley]

Some progress

OK guys. I took off the carbs again, made intake gaskets, re-checked all the jets and choke assemblies for cleanliness and reinstalled. Also set the sync screws for throttle valve opening. Tried to sync without the gauges and did pretty good I think. Pretty smooth running. Took off the airbox to check vacuum at the carb. Felt pretty good. Bike started up fine and idled ok as well. A little popping in carbs but I adjusted the sync screws a little and it settled down. I also sprayed each intke to see if there wee any leaks and it didn't make a difference. After warming it up I checked the timing. It was a little off the F mark but I have no adjustment on this bike. It still seems to pull too much. When I accelerate it takes a little time to come back to idle and sometimes it stays at a higher idle. It's running pretty good right now so I may take her for a ride tomorrow after I reinstall the airbox and see if there's any real quirks with her. Any other ideas? Thanks for all the help.

[tarzan]

Ok, if the idle hangs a little bit before coming down, that is probably the sync.
Now I'm not trying to insult you, just asking to be sure, do you have restricters in your sync lines? If you don't, you will have the readings jumping around too much to sync. The hoses have to have a small orifice in them to get the vacuum low enough.
Also if your timing is off and you can't loosen the timing plate due to the heads are sheared off at the factory, you just take a drill and drill the heads
(nubs) off.Once you drill all three heads off, the timing plate will come off and you can replace those screws with socket head cap screws.Then adjust timing.
However, until you can get the carbs to idle at the right rpm, I wouldn't take the timing thing too serious yet. I would get the carbs right then get the idle right and check timing. Your timing won't read accurate till the rpms are right.

[CatatonicBug]

Don't try to sync the carbs without the airbox (or pods) installed. The restriction that the filter(s) create is part of the tuning process. You mentioned that you "adjusted the sync screws a little". Do you mean that you sync'd the carbs properly, or just arbitrarily turned them? What tool are you using to do your sync?

Remember that the air/fuel mixture screws need to be adjusted too. You did remove them and clean under them, right? Once everything is clean, you need to re-sync, then adjust the mixture screws, then sync again.

[mro]

I got #1 to come into the normal range but 2 wouldn't move.

JIC...

#1 is synchronized to #2
(When you turn the screw for #2 it is linked to #1, so it also opens/closes #1
as you adjust #2 to #3)

#4 is synchronized to #3
Then #2 synchronized to #3

There's no synchronization screw for #3 (#3 can only be opened/closed
with the idle adjustment screw which moves all of em.

I'd check the headers to see if they are all getting hot about the same.
A pilot screw out of adjustment as little as a quarter turn can keep a cylinder from firing or firing weak at idle as well as a bad plug, coil, plug cap or wire...

mro

[jmailley]

Still checking things

I found out the #2 guage is bad. I also put the gaskets on the intakes one of you suggested and that helped. Seems there's no more vacuum leak. Checked timing and it's off a little but I'll stay on the carbs to get them right before drilling out the timing plate screws. It's definitely running smoother but I'm looking to get this purring. I have a tach but which lead do I attach it to? The manual doesn't say, just go by tachs instructions, which I don't have.

I'm gonna keep plugging along and I truely thank all of you for all the help. Some day I will return the favor.

[bikerphil]

If it's a non-inductive type, it hooks to the neg. coil input (org or gry). Inductive type hooks to the spark plug wire.