what a difference a good synch makes

[gk45241]

Duh, I know you all probably already know this but wow!

Thanks Doug for your time!

A whopping 8 mile ride later and I am confused though. Vacum problems have been checked and addressed. When we got done synching the bike the idle was great. The longer I rode the higher the idle would creep up. I double checked to make sure the throttle was not sticking. At every stop it seemed to stick a little higher until it was between 3-4k.

I did not change any of the synch settings but rode back home and adjusted the idle back down to a respectable level. It still warms up while riding and the idle still is sticking in the 2-3k range.

Do I need to drop the idle a little further and thorughly wait for it to warm up before canceling the choke from now on? or is there another grimlin going on here?

p.s. For a bike you said still would run well until i get the new coils etc...all I can say is DAMN what a change. Got to run with a hardly D coming back up creek. Flat pulled and smoked him for the mile stretch up to my sister in laws. He stopped in and asked if I had put a crotch rocket engine in an old school frame. NOW I UNDERSTAND WHY YOU ALL LOVE THIS OLD BIKE!

Gary

[cywelchjr]

If they are in sync, it sound like you didn't adjust the idle mixture and it's too lean, which can cause this type of problem. There might be other things that cause the same thing as well, but the one I have run into personally is the idle mixture being too lean, and richening it out a little usually fixes that.

[tarzan]

A vacuum leak can cause idle to climb and hang.I.E. cracked carb holders or hose or vacuum diaphragm

[Dragon Tamer]

As Tarzan has pointed out, a vac leak can cause this problem, I see that you have checked this out, please do so again and pay close attention to the sync ports as you have just used them and may have caused a leak.

Sometimes when you sync you can also cause other vacuum problems and I would recommend that you re-sync once again to make sure that all things are still where they belong. If you are using a single gauge setup make sure that you are syncing at the same rpm for every cylinder.

It sounds as though you are really close to where you need to be and just need a little touch more to hit the jackpot, keep us posted!!!

[79XS11F]

This is a common problem and I myself have had this issue as well. You sync the carbs and the bikes runs great. Then in use the idle creeps up until you have to dial it down. Runs great until the next time you use the bike. Then you seem to need to turn the idle up again. This is because the sync MUST be completed when the engine is at FULL operating temperature.
So, go for a run and get the engine up to full operating temperature and re-sync and set the idle as soon as you get back from that run. If there are no other issues this will correct things for you.
Rob

[gk45241]

no vacum leak

ok since i didn't synch these i gotta ask. Where is the idle mixture screw? is this the main idle screw located in the middle of carb 2-3?

Gary

[jjwaller]

ok since i didn't synch these i gotta ask. Where is the idle mixture screw? is this the main idle screw located in the middle of carb 2-3?

Gary

It's the big brass screw on the top front of all the carbs.
If you have later ones, there's an EPA cap on the port and must be removed.
See the carb FAQS.

[gk45241]

idle mixture screws.

I assume that these are the ones covered by the plastic caps on my 79sf?
What do I want to do to these to get the idle in line? Is this going to totally screw the previous synch if I adjust them since I would assume that all 4 need to be set the same?

Gary

[jjwaller]

Didn't know they started with the caps in 79.
Anyway, if they're still capped, chances they are the same setting.
But yes can affect the sync.
Would always recommend re-syncing after any carb adjustment.

[79XS11F]

ok since i didn't synch these i gotta ask. Where is the idle mixture screw? is this the main idle screw located in the middle of carb 2-3?

Gary

Yes, the main idle adjustment that idles down, or up all 4 carbs at once is that large knob between 2 and 3. The other screws the lads are talking about are for adjusting each individual carb.
Rob

[tarzan]

Idle mixture should not change the sync.The butterflies will all be open the same amount after sync.That is the purpose of syncing.You should be able to do like XS11F said and run to operating temp,sync,then adjust mixture screws.You may have to adjust the idle speed during sync or idle mix adjustment.You want it to run approximately 1050-1100 rpm.I set the idle speed then start the adjustments.BTW-the idle speed is adjusted with the big screw between the two middle carbs.

[DGXSER]

Hey Gary, did Doug also colortune your bike as well? knowing Doug, and how maticulous and anal he is (almost as bad as me ) I bet he did. So I doubt you need to mess with the mixtures, may be wrong, but just a guess.

I would look to see that none of the port caps are loose or fel off. Next thought would be to try warming the beast up really well and have another go at the synch.

BTW, she turned out REALLY nice!!! Awesome job!

[gk45241]

colortune

Doug threw the color tune on plug one but I have a weak spark. I need to get my plugs caps, coil wires and a dremil..lol or just order the full kit. Cant do that till the checks start rolling back in or I get a lump sum check in NOV.

Since the spark was weak and I was going to change we did not yet color tune.

Thanks, I think she is coming along nicely, But not close to being done by a long shot. Hust now getting to the respectable stage. along way from the resto and bobbers I have seen people with on here. One step at a time..hahaha

P.s. I'll give doug a call but I don't think he's gonna wanna resynch or mess with the mixture screws till I get the coil issues taken care of.

Gary

[dbeardslee]

Gary - I've got a set of coils in the mancave that I was planning to rewire. Probably won't get to it until sometime next week - today I'm getting ready for all the little beggars. Problem was that the spark was so weak I couldn't see much through the colortune. It was firing - just very weak. I'd like to put the DMM on it too and see what the pickup coils are reading. All the fluid that's leaked down over the side of the motor by the neutral switch has me a little concerned. There's fluid/gunk all over the sheathing where the neutral switch wire exits the harness, and it's possible that it's gotten inside the sheathing where it can cause problems with the factory splices. The other thing that has me thinking coil/electrical issues is the way it was backfiring through the carbs. I'd like to check the timing on it too. Once I've got the coils ready, if you can get it over to the mancave we can test some theories. Sounds like it's running well enough to make the trip.

In the mean time I strongly suggest you look for a left front caliper. Running that puppy without full braking is a mistake - it can get you into real trouble. Even when the brakes are right, these big heavy bikes don't like to stop. Take it to an empty parking lot, goose it real good in first gear, and then try to stop quickly and you'll see what I mean.

[gk45241]

coils

Yeah I think it might make the trip now .
If you decide to do the coils you have I will trade /pay you for the difference if that is the issue. I appreciate all the help you guys have been giving me.

Like betsie.. I think it may become the beast I desire but may never be fully done.

Gary