Vacuum Syncing Issues

Okay, here is what I have done so far to the bike ('82 XJ 650J).

1. Replaced all o-rings and seals in the carbs.
2. Cleaned the carbs well, they do pass the clunk test.
3. Put the carbs back together.
4. Bench synced them so that only a small strip of a business card would fit underneath them.
5. Checked the fuel levels (however) I didn't adjust any because it looked like they were all 3 mm under the top of the bowl where they're supposed to be.
6. Replaced the intake manifold boots as they were pretty cracked.

When I initially put the carbs back on, the bike started, but ran at like 5,000 rpms, so I backed the idle set screw off a bunch and then it was idling at like 1,500 with just a touch of choke. If I took the choke all the way off it would die.

I thought that was just an issue of not being synced properly. It started pretty reliable and ran okay actually. I could ride it around but it wasn't really smooth and hesitated a bit.

I just went to go sync everything, and I have no idea what I'm doing. All the gauges are going crazy, I do have the YICS tool from chacal and it was in. I changed the idle set screw so that I could turn the choke all the way off and then I messed with some screws, but I have no idea what I'm doing. I know I made it worse. In fact, I couldn't even get it to start with the YICS tool in, but it would start without it in.

I feel like I'm in way over my head, and I'm guessing that I need to take it off, bench sync it again and try over, but I'm worried I'm going to have the exact same problem.

Any advice? I couldn't find a really good guide on vacuum syncing on this website, so I figured it would be easy, but it doesn't seem to be.

Thanks!

 

Did you check your valves? Are they in spec? This is step one before any carb tunning.

 

Oh yeah, sorry, valves are in spec. 5 of them got changed.

 

If the engine will start and run under it's own power, then your bench synch procedure worked and you're done with it.

The vac synch will eventually take care of the rest of the issues. What type of gauge are you using for the vac synch?


Here's a great tutorial on using the Carbtune Synch Gauges:

http://www.youtube.com/watch?v=CYgN2-96 ... re=related

 

What do you have the pilot air screws set at? Mixture needs to be set before synching.

 

Dzjensky,

DON'T panic. You're not in over your head and you're not going to kill it. You just it farther out of sync. Take a deep breath, relax, we're here, and we'll get you through it. Just stay with us and again....don't panic. Many of us were in the same spot at some time in the past.

Dave

 

After all of the running issues you had, similar to what my bike was doing, found plug wire to be screwy with a couple of fouled plugs and that helped, like u had torn apart carbs several times, and its a bitch. Stick with it will make you wiser and the satisfaction you receive when you get it is like a high that cant be beat, also check mixture screws and order of parts, as in screw spring flat washer and o rings and that spark is abundant, I know how you feel, I feel like my maxim is haunted by my xwife.

 

Do your gauges have restricters installed to dampen the vacuum to the gauges? Without restricters the gauges will fluctuate wildly. They are installed about 4 inches away on the carburetor side.

 

I tried to set all pilot screws were all set at 2.5 turns out.

I have this sync gauge. http://www.motorcycle-superstore.com/61 ... B22P_D_BwE

XJOE550 - I have no idea what you are talking about. I have never used one before. What do the restrictors look like?

 

Well, great, I'm an idiot. It has these clear plastic valves that it says to install on the carb sync to keep it from swing wildly.

I had watched this video on the topic and he doesn't use them https://www.youtube.com/watch?v=t0qf11BOx6o.

Also, I dropped the bike taking it off the center stand to roll it back into the garage. Not a good day overall.

 

At least you figured out what the restrictors are. They should have a very small hole so they restrict the air flow.

Sorry to hear about the bike falling over you can worry about that once it runs properly.

 

The restrictors should be near the engine, not near the gauge. The piece of hose between the gauge and restrictor helps damp the gauge oscillations.

The restrictors are adjustable. You want to turn them in to where the needle on the gauge just wiggles a bit. If you try to make it perfectly still you may close the hose completely and the gauge won't move no matter what you do to the engine.

The vacuum hoses that come in that kit are very poor quality. Plan on getting at most a few uses from them. When you're near the auto parts stor get 12' or so of good vacuum hose to replace them.

 

Okay, I put the restrictors in and it works like a charm. Those needles remain pretty steady and I got them to where they stay within the distance of one hash mark.

Here's the problem (maybe not), they're all bouncing in between the same hash marks, but I seriously changed nothing.

Also, with the YICS tool in I have to practically give it full choke to get it to keep running. Eventually it started idling at like 3k rpms, so I backed it to half choke and it was running at like 1,500 rpms. Again, all needles bouncing in roughly the same area.

Then, when I pulled the YICS tool out, there was a very small amount of black fluid (I assume oil) on the black washer furthest from the opening. None anywhere else.

Something tells me that it isn't really synced and that I've done something wrong, but I want to hear what you all think.

 

Don't use the "choke." The choke is an enrichening circuit. If you need to boost the idle with the YICS tool in place, turn the idle knob in enough to bring it up.

The fact that you CAN use the choke without immediately killing the bike tells us that it's not warmed up fully so you won't get an accurate sync. If the motor was fully warmed up, any application of choke would cause it to stumble and die from being way too rich.

Get the bike fully warmed up first, then use a house fan (box fan) to blow air across the motor while doing your sync. By fully warmed up, I mean 10-mile ride warmed up.

 

...soooooo 10 minutes idling in the garage isn't good enough?

Thanks Fitz.

 

Ummm... nope. Not even. (Learned this from experience myself.)