Spark plug gap, Colortune, Clip-ons, Valve Clearance, etc.

1982 XJ550 Maxim

1. What is the recommended spark plug gap?

2. Does the YICS tool need to be in place to properly Colortune?
-my guess is "yes" so that each carb is isolated to it's cylinder, but just checking...

3. Valve clearances should be done with the engine cold, correct?

4. I appear to still be getting a vacuum leak around the front of the carb, which I am working on... I read somewhere during the hours I have spent reading on this forum, that the leak may be coming from the enrichment valves not seating properly when the choke is off. Is this a common source of leaks?

I do have some cracks on the outside of the carb intake boots, but they don't appear to go all the way through.

I am not looking forward to taking the enrichment system apart and have avoided it thus far.

5. Clip-on Handlebars- to anyone who has installed clip-ons... Did you have to remount your headlight?
I ask because Airtech sells mounting hardware b/c they suggest that the original mounting hardware for the headlight will not fit with clip-ons in place.

6. I had a very strange experience yesterday while using the Carbtune. I was running with the choke on, because that seems to be the only way it runs at the moment. As the engine warms, I slowly bring the choke down, but it becomes very finicky and either races to 4000 or stalls.
So, I hooked up the Carbtune (YICS tool in), just to try and get some inkling of what might be going on... Carbs 3 and 4 were fairly close to each other with a strong vacuum reading. 1 & 2 were significantly lower, with 1 lower than 2. There was very little movement of the meter for #1, but some. Then, all of a sudden, I started getting a fluid in the #1 Carbtune chamber. I immediately pulled the hose. No fluid flowed from the tube. I forgot to smell the tube at the time
When I pulled the carbs, the intake boots were pretty wet with fuel, but I assumed that was because I was running with the choke open.

Has anyone ever seen this before?

Thanks so much for your help.

 

1- .023"~.028" I generally start at .025" NGK D8EA.

2- Yes. Colortuning is the "visual equivalent" of what the factory did using an EGA. And the EGA manual specifies the use of the YICS blockoff tool.

3- Yes. Or at least cooled down enough that you can touch it; if it's still a little warm it will be fine.

4- No, enrichment valves won't cause a vacuum leak.

Re: Cracks in the intake boots; they usually don't go all the way through. Test by flexing from the inside when the carbs are off. I packed mine with black adhesive RTV and they're fine.

The enrichment mechanism only looks complicated, it's not. Here's an exploded Mikuni just like yours: http://xjbikes.com/Forums/viewtopic/t=31061.html

5- Can't help you there; I've got low bars on both of my 550 Secas, not clip-ons. No headlight interference issues.

6- You're trying to use the Carbtune way too soon.

First off, get the valves in spec or you won't get a valid sync.

Then, FULLY clean the carbs, and set the float levels using fuel and clear tubing. The 550s are really finicky about float levels.

Then do a nice precise bench sync.

Then after the carbs are back on the bike, it will run. Get it fully warmed up before you try to do a vacuum sync. You can't sync with the enrichment valves open; the bike has to be running with them off. If it won't, then your carb's ain't clean somewhere, plain and simple. Or the float levels are way off or you missed on the bench sync.

Your Carbtune sucked gas because you've got a float level that's way off or a balky float or a bad o-ring on one of your needle seats.

You HAVE to go through the above steps in order, especially if you're going to attempt to tune for pods. Trying to charge into the middle of the process won't work.

You're also going to have to be careful, patient and precise. These Mikunis are precision instruments with some of the tiniest holes and passages possible, and if they're not completely clean and properly adjusted they will not work correctly. You're going to have a big enough challenge with the pods; everything else has to be 100% first or you'll never get it to run right (if at all.)