Is this a YICS engine?

I know this is a stupid question but Ive read that 82 and newer models are YICS but I have an 82 XJ650RJ and I can not find the YICS hex plugs. Can anyone tell me if this is YICS engine? If so, can you point out the plug for me?

 

irishladjbl, your pictures are not very clear on my computer monitor, but you have plain case covers (at crank ends), so I don't think you have a YICS engine.
Here's a picture of what you're looking for:

 

Thanks Nick. I appreciate it. I was thinking the same thing but all the stuff Ive been reading about syncing the carbs says that I need to use the YICS tool in the 650 and 750 models for 82 and newer. Im having problems adjusting the air fuel mixture screw because a small adjustment to one carb affects all the other cylinders. Is there another way to isolate the cylinders?

 

The '82 650 Secas were not YICS engines. If you look closely at the top end, there are a lot of small differences between this engine and the YICS equipped powerplants.

 

Non YICS engines don't have the carbs interconnected at all, the cylinders are isolated from each other. Adjusting one mixture screw on one carb will not effect the other carbs. The only thing that I can think of is your RPM may be changing as you make adjustments.

What kind of effects are you experiencing?

 

That is true, when I adjust one carb, the RPMs did change. I tried to colortune method of adjusting each carb but as I was working on one, all the other plugs fowled. I was making my adjustments without the vacume gauge connected though. Im going to read my Haynes a bit more and figure out what is going on here.

 

follw the procedure steps in the manual to the letter and you'll have no problem, i use a set of mercury tubes that i got from jc whitney for approx $65. they are worth the money, set up a fan in front of the engine when you sync the carbs in, this helps keep the engine cool. i wouldn't have thought you can use a colortune to sync the carbs in.only to set the mixture. are you altering the pilot mixture screw that is preset from the factory?

 

mcfc again, i have had a 81 non yics and i now have 2 82 yics maxims and a 82 seca turbo. the valve cover on a non yics does not have the black and aluminum striping on it or the side covers with yics on them, i prefer the later model (yics). take you time don't worry if the revs go up a bit as youonly have to back off the idle screw in the middle of the carbs.

 

Start with all mixture screws one and a quarter turns out. Then use the colortune to set cylinder one taking note of how many turns. Eg, if you end up finding the colour at 2 and a half turns then set all the others at two and a half turns.

Reset your idle and then check no 1 again. then do 2,3 and 4.

Basically if your plugs are fouling then they are set wrong so by doing one and matching the other three by turns you are quickly putting all cylinders "in the ball park."

I always keep the sync gauge hooked up when colortuning so I can fine tune as I go across.

Four colourtune plugs would be heaven if I could afford them.

Cheers
HG

 

So which do I do first? Sync or air fuel mixture? The Haynes manual does not have any guidance because it say to "NEVER TOUCH THE AIR FUEL MIXTURE SCREWS" becasue they are factory set. Unfortuanately after a carb rebuild, they are NOT factory set any more.

Is it worth it to use the mercury tubes instead of the home made tool Ive been seeing passed around this site?

 

I would suggest that you set the sync first, then move to the air/fuel, then back to the sync. It is a balancing act, just like syncing the carbs, sounds redundant but I can't think of another way to put it. The home-built sync manometers are cheap and effective. I prefer the vacuum gauges myself ($50 from JC Whitney) as there is no oil or mercury to worry about. Get in there and do a base-line on your butterfly valves (this means pulling the carbs), set the air/fuel screws as Hired Goon suggests, then proceed to the sync. You should be able to get everything close from there.

 

I think we should Poll everyone that's done a ColorTuning and get a good idea of how much more Out, beyond the base Factory Preset 2-1/2 Turns Out, is added -- to increase the adjustment -- to where that ideal "Bunsun Burnner Blue" combustion Air/Fuel Mix results.

 

At carb clinics I always hook up the mercury sticks and then start on #1 cylinder with the colortune. I always have the owner ride the bike and get it up to operating temp before I start. This way I have no cylinders running cold and I can see how far the sync is out right away. If it is really out I will sync some first. IF it is way out and I have a cylinder missing then I will wait until that cylinder is hitting and may start the colortune on that cylinder. The sync affects the air portion of the mixture and the pilot mixture screw affects the fuel portion. So one influences the other. You can see this on the mercury sticks when you bring a missing cylinder back up.
The factory setting of 2.5 is only a starting point. I would recommend 3 turns out after a carb cleaning to get the bike running. Very few cylinder run a bunsen blue at less than 2.5 turns out. At least that has been my experience. Someone like D.V. who has tuned more XJ's than I have seen will have better data. Most of my carbs are at 3 to 3.5 turns. And I cleaned them quite well. I had 2 missing cylinders at 2.5 turns out.

 

I agree, set your mixture screws 1st to 2 1/2 turns off the seats.
Then sync your carbs.
Then set the mixture screws with colortune.
Check and reset sync
Readjust mixture with colortune and check sync.

If all is good.....................GOOD

If not keep it up till it is right.

This is all provided you dont have any other carb problems.

Good Luck


BTW: Irish that aint no YICS engine

 

Irishlad,

The '82 XJ650 Seca that was/is Silver has a non YICS engine originally. Later in '82, Yamaha released the XJ650 Red Seca that had YICS.

Assuming your bike is a 1982 650 Seca, I see you have the Silver tank so Non YICS.

Regarding the carb setup. I've used the colourtune and man, what a difference. That thing is definitely worth the money. I synched my carbs using a homemade manometer but I haven't tried it with the carb sticks yet so I have no basis for comparison.

Good luck tuning.
Rob

 

So what do I do if I can not get the bike to idle with the mixture screws set to 2.5 from bottom?

I tried to sync the carbs with a home made manometer but I could not even get the bike to start without starter fluid at 2.5. Right now I have the mixture screws backed all the way out to 3.75 and the bike backfires like it is not getting enough fuel. also, the RPMs rev really high then slowly come back down when I let the gas off.

 

The 1982 XJ650RJC was YICS equipped. However, this bike was only sold in Canada, the US received the more common XJ650RJ exclusively.

 

Irish,

If you are getting backfiring, you are probably getting too much fuel. Lean conditions can backfire too but it is less common. One thing is to check that your choke (fuel enrichment system for you hardcore guys) is not on. I had this a while back where I was getting a rich mix because I always had choke on. If choke is off (be sure by loosening the cable at the bracket), you may have an air leak in the carb boots. Some RTV silicone is what others here have done (I think) to seal the leaks.

What do you mean by revving high then it comes down when you let off the gas? When you are on the gas the bike should rev higher?

 

Thanks Fraps, Ill try that. If that does not work, where should I start the troubleshooting?

 

Usually the fast idle then dropping off thing; means you need to start by syncing your carbs and you should have the mixture screws set where it runs best then resync then reset the mixture screws and repeat a couple of times just to be sure, if your a real SMOOTH running finatic.

Like me.

 

Unfortunately, I can not get it to run "smooth" at all. I tried to run it starting at 2.5 turn out, then backing the screw out .5 tuns successively, checking the plugs each time. I can get it to start on its own but only with the screws out almost 4 turns. That has to be way too rich. Any ideas? I can really use the help.

 

Just a guess here, but I'm thinking you either have a heck of an intake leak, or blocked pilot jets. Check for intake leaks by runing the engine at whatever RPM it will idle at decently, then spray WD40 on and around the intake boots (carb-to-cylinder head). If the RPM doesn't change, they're OK. I'd then turn my attention to the carbs themselves; they will most likely have to come off and be cleaned. Read Rick's carb cleaning primer and go to it!

 

also to make it idle the 4 turns or 2.5 turns are all relative.
If it idles good enought to sync it at 4 turns and it doesnt soot up the plugs or leave them wet.

What Captn' says about intake leaks and blocked jets sounds the most logical.
If you do have to pull those carbs Rick did one heck of a writeup, the man ought to write instruction manuals.