Carb Synchronization

I get the jist now. I wasn't thinking when I asked that. Thanks Fitz

 

I found out O'Riley has them but usually not in stock. The guy ordered it from the warehouse today. Should be there tomorrow.

It just baffled me that none of those guys knew what the heck I was talking about when I called. I actually had to go online and find the part number for him.

Oh well. At least I found one.

 

Good going.

Amen. This has become my standard M.O. when dealing with O'Reilly, AutoZone, Advance Auto and even NAPA. Don't even walk into an AutoZone and ask for "NGK" anything; but give them their own damn SKU and lo and behold, how many dozen do you want? I've done a bunch of semi-major repairs to both my VW and my son's Mitsubishi in the last couple months, and in every case to get the right part, I had to tell them what it was. AZ actually calls their staff "Autozoners." What else can be said?

 

They're certainly "zoners" that's for sure. Most stores are like this nowadays. I do IT work and when I go into best buy I get sick to my stomach at the lack off technical knowledge those morons have. All it takes is a little research and you can run circles around just about anyone these days. This is off topic but I went into a McDonald's one day and asked for a plain cheeseburger. The girl asked me "do you want cheese?" Wtf.

Anyway, I picked up the gauge I ordered from O' Rilley's tonight. Exactly the one you said. It's a gearwrench 2274D. I'll be checking the exhaust valves tomorrow.

 

There you go.

Also, keep in mind that shims only come in .05mm increments; the one you thought said 278 is probably a 275.

 

I dunno Fitz. I may be losing my mind but my eyesight is still pretty good.

Check out the pic.

 

rig yourself up an aux fuel tank......and run a line to the carbs....

 

Got a portable work bench? They work great for a lot of bike stuff including setting the gas tank on for use as a auxilary tank. Note: Lay two cut to length 2x4s across work bench so the petcock lever can be turned and to keep it off the table. I also use this set up for the vacuum sync and colortune.

Gary H.

 

Here's some other wacky ones that were in the exhaust valves. 272 and 268.

I guess I should be rounding these off?

Something I don't understand. My cylinder 1 exhaust valve measured 0.19 clearance. The shim was a 272. If I round that down to 270 and refer to the chart it says to keep the 270? Am I reading that correctly?

 

Something's wrong, there are no 278, 272, or 268 yammy shims. Maybe in Suzuki. Better measure their OD and make sure they are 29.00mm (exactly) OD.

 

I'm assuming this is bad? Now what the heck do I do?

 

Get new shims to replace all of them that are that size!!! That's a disaster waiting to happen............

 

Ok. But I have one 280 shim and it's the same size. All the shims in there are about 25.00mm OD and fit tight. Honestly I don't think another 4mm will fit in the buckets.

EDIT: Just found this. Apparently some xj600's do take 25mm shims. Look at the chart.

http://www.sudco.com/25valveshims.html

 

Whoops, my bad...............yes the XJ600 Seca II models do use the 25mm OD shims, I thought you were working on an older XJ model! Apologies for the confusion and whatever else (anger, suicidal thoughts, etc,) I may caused you........

 

It's a 93.

No worries. I had the suicidal thoughts and anger way before you said anything. None the less, thank you for trying to help.

Any idea how I need to handle these wacky shim sizes? I guess I just need to round them off?

 

Well, you'd still calculate the "shim size needed" in the usual way........the clearance specs are wide enough so it won't matter that there are "odd sizes" in there to begin with....

 

Yamaha 25mm shims for the Seca II come in .05mm increments, just like the ones for the older bikes with 29mm diameter shims.

I don't know where the heck shims with those sizes came from, but they're not Yamaha parts.

Len's right about the range; you should be able to calculate required shims by measured clearance and "rounding off" of the installed shim to the nearest .05mm.

 

Ok. So I'll be rounding. Based on that here are my findings. See what you guys think.

Intake

Cyl #1

Measured clearance - 0.14
Installed shim - 278
Required shim - None, In spec

Cyl #2

Measured clearance - 0.15
Installed shim - 278
Required shim - None, In spec

Cyl #3

Measured clearance - 0.08
Installed shim - 280
Required shim - 275

Cyl #4

Measured clearance - 0.17
Installed shim - 278
Required shim - 285


Exhaust

Cyl #1 - This one confused me. Rounded 272 down to 270 and according to the chart it requires a 270 so do I just leave it alone?

Measured clearance - 0.19
Installed shim - 272
Required shim - 270?

Cyl #2

Measured clearance - 0.25
Installed shim - 272
Required shim - None, In spec

Cyl #3

Measured clearance - 0.25
Installed shim - 268
Required shim - None, In spec

Cyl #4 - Another confusing one. Same as cylinder #1. Should I put a 270 in or just leave it?

Measured clearance - 0.17
Installed shim - 272
Required shim - 270?

 

On C4I (Cylinder #4, Intake) I would use a 280 (rather than a 285) shim...it will reduce the clearance from .17mm to .15mm, which is in spec (high end of spec, but within spec nonetheless). Remember, clearances will DECREASE over time with engine usage, so there's nothing wrong with being at the high end of spec range.

On C1E, you are already within spec (0.19mm), so no need to change from the currently installed 2.72mm shim).

C2E is not within spec, which I am assuming is .16 - .20mm for exhaust valves. IF that is the correct spec for exhaust valves on your engine, then you'll need to use a 2.80mm shim to arrive at a .17mm clearance.

On C3E, same thought applies, you'll need a 2.75mm shim to close the gap down to .18mm (= current .25mm clearance, less .07mm increase in shim size).

C4E is within the (assumed) spec range of .16 - .20mm for exhaust valves, so leave it be.

 

if you measure a yamaha shim with a good set of micrometers, rarely are they exactly whats marked on them. yamaha might have marked that 2.72 shim as a 270 when it really is 272. i'd just call that one a 270 and move on.

 

The chart I have from the Haynes manual says;

• Intake is within spec between 0.11 - 0.15mm.

• Exhaust is within spec between 0.21 - 0.25mm

Both when the engine is cold of course.

So based on the tolerances in the manual wouldn't my calculations be correct?

 

That is why I try to buy my tools, and as many parts as I can, through the local farm implement dealer. They still have parts people who can read a book.

 

Okay, with the proper clearance specs, then these are what you'll need:


INTAKE:

C1I and C2I are within spec, leave them as-is.

C3I needs to be changed to a 275 shim as you calculated

On C4I (Cylinder #4, Intake) I would use a 280 (rather than a 285) shim...it will reduce the clearance from .17mm to .15mm, which is in spec (high end of spec, but within spec nonetheless). Remember, clearances will DECREASE over time with engine usage, so there's nothing wrong with being at the high end of spec range. That 280 shim that will be coming out of C3I can be used here.

EXHAUST:

On C1E, use a 270 shim, that will increase the clearance to .21mm, thus in spec, and probably when you check them again in 3 - 5000 miles, that gap will have closed up some, and you'll then need to go to a 265 shim.

C2E and C3E are both within spec, no changes needed.

On C4E, I would go down to a 265 shim, this will increase the gap from the current .17mm to .24mm

 

Thank you sooo much chacal. I really appreciate the once over.

One question. Would it be detrimental to just go ahead and put the 265 shim in C1E now so I don't have to pull her all apart again in a few months?

 

Well, you could, but that would put the clearance at .26mm, which is out of spec. I'd rather advise you to do it properly, even if it means knowing that you'll have to do it again in a while, because that's what "doing things right" means! Besides which, you really do want to get into the habit of checking/adjusting the shims on a regular basis, the next time around it won't seem like such a pain.......

 

Sounds good. Once again, thank you.

 

Keep in mind that the next valve check is in 5,000 miles. The more hours that the engine has on it, the less often the valves will be out of spec; you really should never play with the idea that a valve will work its way into spec as the engine is run.

 

Gotcha. Thanks.

 

Specs from the owners manual and shims needed if I wanted to go stock Yamaha shims. Column "I"

 

You will find that all this effort to do the valves and carbs correctly will be rewarded with a great running engine. The way it goes, in spec is in spec and not in spec is not. You are going through the toughest part of the ownership of one of these bikes and that is to catch up with the required maintenance and safety issues. You will see that, for the most part, you will have trouble free riding for many seasons after this.

 

Well, I got the valve adjustment down pretty good now thanks to all you fine folks. I know what I need and I know how to do it. Next it's off to the races with those @^!%$* carbs. They should be ok because I rebuilt them last season. New seals all around, new float valves, new gaskets, floats adjusted, etc... I still have to wet set the floats though. It still confuses me as to why two of the four would not have any vacuum though. Even after a bench sync AND a dynamic sync. I dunno. Takin it slow and steady. One problem at a time.

 

did you ever try 1 to 3 or 2 to 4, dono what that will do but your running out of options here
sometimes if you hold a hammer while you talk to it and use a lot of bad words it'll get the message

 

did you ever try 1 to 3 or 2 to 4, dono what that will do but your running out of options here
sometimes if you hold a hammer while you talk to it and use a lot of bad words it'll get the message

 

Yessir. I tried 2 to 3, 1 to 3, then 2 to 4. Carbs 1 & 2 are totally out of sync with 3 & 4. I just want to get the valves done first. Who knows. Maybe it might just solve the problem. If not, I'll try the hammer. Heck, I might even try a chainsaw.

 

But not on an XJ

 

In the manual it does state that the valve clearances will be have to be in spec prior to carburetor synchronization.

Since I am Southern, I will translate, "it ain't gonnas work until them whatchamcallits are straitened out, then you cans get to the sinking of the carbies, just ain't no sense wid fiddlin wit it until t'en."

 

Being from NYC and now living in NC, I can actually understand what you just said. Scary.

 

Well, maybe not........

http://xjbikes.com/forums/index.php...rtng-problem-surpise.46358/page-2#post-414262

 

You did.

This is better than the manuals: http://www.xj4ever.com/setting fuel levels.pdf

And again, unless the valves are in spec, you can't effectively tune the carbs.



bigfitz52, Sep 28, 2014Report
#20LikeReply


Just going by what Fitz posted...jeez..
Guess some peoples two cents ain't worth putting in.
Think I will just keep mine..

 

If you don't want it I'll take it. I'm gonna be broke after I get through with this bike.

 

Just to clarify, the link I posted is actually to make crystal-clear that while valve clearance adjustment is not MANDATORY before you synch, it's quite possibly a VERY unwise move, since you'll be synching the engine to (possibly) a MUCH lower standard of performance.....

 

If the valves are out badly enough, it won't synch. It'll bounce all over, race, and refuse to return to idle consistently. Plus the sync will change drastically between cold and hot.

 

Ok guys. Here's the skinny.

I got all the shims I needed and popped em all in so the valve adjustment is complete. All are in spec and she's all back together.

Next on to the carbs...

Adjusted the floats (dry and wet)
Adjusted pilot screws
Did a bench sync and...changed out the main jet o rings and pilot screw o rings.

When I was changing the o rings in the main jets it looked like they were squashed and blocking the hole. I don't know if that would cause a loss of vacuum but the pilot screw o rings looked shot too so might that have cause it as well? They were all very hard and brittle. Anyway, after I replaced those o rings I put the carbs back on and did the dynamic sync and all was well.

One question, those main jet o rings. I want to make sure I have the sequence correct. First the metal or copper gasket goes on with the main jet holder. Then the o ring goes in the top and the main jet get screwed in. That sound right?

 

Valves adjusted, carbs cleaned, floats adjusted and synced. Bike is back together. Took it for a quick test ride today. Rides nice.

I just want to thank everyone for all the help. I really couldn't have done it without you all. You guys saved whatever little hair I have left on my head from being pulled out. Thanks again.

 

If you dipped these carbs in a cleaner, hopefully you removed the throttle shaft seals & fuel o-rings , & the o-rings in the pilot mixture screws

If not, you need to replace them. The carb cleaner will turn them to mush.

3MM +- 1MM on float level


Valve clearances is top priority.....do not shortcut this process.......

 

Check out the thread. Everything is all done and back together. Thanks for the input though.

 

You have it right, you can tell from this discussion in the post where you got the picture in your other post on main jet o-ring:

From XJRider.com:

"But at close to four bucks a piece I think it's time to do some experimenting with alternative o-ring types or try and run without them. If 10ldman has been running without them, I see no need for further evidence there

There has to be another o-ring that will work, though. All they have to do is bridge the gap from the base of the main jet to the emulsion tube, so no initial gas gets to the outside of the emulsion tube from the jet. The OEM o-rings in the picture are made of a material that disintegrates way too quickly. Perhaps the alternative should be made of nitrile or something like that. The upper set of o-rings in the picture are obviously the ones I was replacing, but they weren't in there for all that long. Maybe a couple months.

If you do go the route of the main jet o-ring, that little copper washer at the base of the holder is pretty important. If it's not there, the o-ring will get squashed too much since the space between the main jet and emulsion tube has become smaller (if that makes any sense)."



If it was not right, it would be like upping the main jet size and bike would run rich, particularly at high throttle.