Tune by ear for now?

Hey guys, waiting on doing the valves... but I KNOW cylinder 1 is too lean, and 2,3 and 4 are all to rich. Can I try adjusting mixture to even them out right now? Maybe turn out cyl 1 a turn and 2,3,4 a turn in?

I know this because
a) left exhaust is much hotter
b) I can FEEL and hear one of two fires missing in my left exhaust
c) right exhaust is nice and smooth, but reeks of fuel.
d) mileage seems real low (35 or so mpg)
e) idles a bit off because cyl 1 is missing. Fires good over 2750k rpm

So, can I play with it for now?

 

One whole turn is a huge amount, try 5 degrees out on #1 & 5 deg in on the other 3. Clean the plugs & do a chop, if you get one the right color, you can adjust the others by marking a glass fuse in the one that is good and adjust the others to it.

 

I would take it out, warm it up on a ride.. come home and check the plugs after idling for a minute or two.. Then adjust idle mixture according to plug color.. You want light brown, and of course the same mixture for all of them, just run it for a minute or two inbetween while the motor is still warm to recheck your adjustments

 

+1 plug color is the way to tell

 

Cylinder #1 could also have a dead tight valve contributing to the problem in which case you can crank carb adjustments all day and it won't help.

Plug color will have to do but I would NOT wait on the valve adjustment.

 

"Clean the plugs & do a chop, if you get one the right color, you can adjust the others by marking a glass fuse in the one that is good and adjust the others to it."

Not sure what 'clean the plugs' and 'do a chop' means.
And do you mean mark a fuse in the fuse block, so I remember which one is right?

Fitzy... I have a feeling that may be the case. Why would one cylinder be so far off from the other? Butttt... if from what I hear on here is correct, valves should tighten not loosen. And I am getting a rough rattle at cold start, then just a light tick when running. Could that also be causing the issue? Tell me if I am wrong, but a tight intake valve could cause nearly the same issues as a loose exhaust valve? And vice versa?

Should I just try a little turning out on cyl 1 and see if the idle evens out a bit? That's all I really want for now.

My list of TODO soon is:
Check valve clearances and replace gasket/donuts
Change to motorcycle oil and new filter.
Sync / Color Tune (when I get the stuff!)
Adjust idle if needed.
Adjust clutch if need be.

Sooooo... tune to get the idle ok for now?

 

The glass fuse trick is a "homemade depth gauge" that helps set the other screws to a cylinder that is working correctly. You drop a glss fuse in the adjustment screw hole of the "correct" carb; mark it; and use your glass-fuse-depth gauge to match the others to it.

Valves DO only tighten as they wear under normal conditions. They DO wear differently; in every motor I ever touched that had out of spec valves none were out EXACTLY the same.

When a valve's clearance is too tight, that valve is opening early, staying open too long, and closing late. You can't tell by the sound it makes.

 

Why not take the guess work out and at least check the clearance on the valves. Even if you can't fix them right now, at least you will know whats up in there. Only takes a little time.

 

Dont forget about float levels.
I tweaked on mine for a couple weeks until I checked the float levels (for the second time).
a little adjustment and my mileage jumped to 45 mpg and ran SO much better.

 

Will take the guess work out of it soon - when I find feeler guages around here. Not sure where to buy them, or what 'set' to buy.
I will check the float levels once I figure out how with the XJ CD lol

Fitz... so, if I have a hard knock 2-3 times when starting up ice cold, then shuts up to just a light tick... what could that be? Def sounds like it's in the valve train... and the idle is skippy on one firing cylinder and it bogs till about 2800RPM.
After that, motor runs great... but ticks a bit.

 

dpawl, these xj's have a normal ticking sound from the vavles when idling/running. I am guessing, but if you had no ticking of valves your cleareances would be tight & just waiting to trash the engine.

 

dpawl the motor will make all kinds of strange noises til you get everything right.

Quoting you here: "and the idle is skippy on one firing cylinder and it bogs till about 2800RPM"
i am hoping you have some concept for the obvious. if your firing on one cylinder the entier engine is out of balance ..... Start your thought process all over with this ... "Why do i only have one firing cylinder"

the reason it smoothes out at 2800 - 3000 RPM is you are now slinging the other non firing cylinder(s) fast enough to have perpetual motion. at that engine speed or greater it isnt draining as great a percentage of horse power from the produced ammout at that engine speed to move the non / improperly firing one(s) around.

if it were me i would start all over with a bench tear down of the carbs, re-sync, adjust.... and check all the seals on the intake boots ..... then move to the valves and check the specs.... i'll bet you find somthing in the process

the initial decribed issue could be caused by an intake boot leak .... causing more air / less fuel to be pulled in by that cylinder.... hence lean on one cylinder rich on 3 others with all set the same on the mix

 

Gregg, I understand the normal tick, but at cold start it is violent sounding for about 1-2 rotations of the cam. That does not sound like a normal tick.

Midnight, 3 cylinders are fine just rich. The first is the one not firing correctly, too lean and that's why it's a lot hotter.
I will check the intake boot. If all is well there, I think I might just try richening that one carb and see what happens.
All I know is the TICK I get at cold start goes away almost completely. The running valve tick after warmed sounds like it may supposed to be there.
But the KNOCK KNOCK when I first turn it over does not sound 'right'.

I am hopefully going to find a set of feeler gauges today.
What could go KNOCK KNOCK and then just stop?

Could too much oil do something like this?
Seems like it started AFTER I did the initial oil change after buying the bike.

 

i recently started a thread about oil weight and at the moment cant remember who posted it but it was mentioned that lifter bleed down occurs with heavy oil like 20w50.... it may not be related to your issue but worth mentioning. sometimes the simple things escape us.

if you are running the correct weight oil for your weather conditions you may be best to go ahead and open it up if nothing else to make sure the valves are right.

 

I have two sets, one I inherited and one I got at the autoparts store. Both are in english and metric and you should be able to find one at any autoparts place and many w***art stores, etc. (I bought the second set because I couldn't find the first since I hadn't a use for them until this bike). They are not expensive and if your valves are out of spec, better to know that than to tear the carbs apart again or chase other monkeys around, no?

 

Get the Valve Clearances read.
You'd have to find a couple way out of specs to knock.
The "Lifters" are Dual-sprung Solids. They don't Bleed Down.

Get a long, skinny PROBE stick.
Tape a short "Flag" of Kleenex to the end.
With the Bike fired-up ... Probe around the Exhaust Collars and Clamps looking for an Invisible Leak.
Those Exhaust Leaks sound JUST Like Engine Knocks when they are cold.

 

CHECK THE BLOODY VALVES ALREADY. Otherwise you're just guessing.

 

Just got a 26 blade set @ autozone for $7.
And a 19mm open wrench to turn the crank.
And some mini philips/flat screwdriver set.
I think RickOMatic had a set for the carbs that he said he loved so I got them for $3.

Midnight - you may be right about the oil. What is lifter bleed down?
I think my castrol I put in is 10w50...? And it has been REALLY cold lately. And it does seem to do it when its really cold out more than when its warm out.
Please explain this lifter bleed down?

 

lifter bleed down occurs typically when the lifer stays compressed for any length of time. what will happen is that the oil will slowly drain down due to the constant pressure.... when you go to start the engine the lifter now has a pocket of air in the lifter that has to pump out....basically leaving the lifter partly compressed... this causes a larger gap than what is supposed to be there, before pumping the air out you will hear some freaky noises coming from the lifters / valves.... once it pumps the lifters up the noise will go away.

this can be caused usually by lifter failure but appearently by oil weight and oil condition as well. still trying to find the a good reference on this. this happens alot on the yamaha xv engines , HD vtwin, etc.... engines due to the agressive cam.

it especially happens when cols since the oil is harder to pump till its hot.

 

Midnight you might just be my hero.
If I change the oil to a cold weather oil for now...
And that sound goes away... I am not in such a rush to check the valves etc!
I DO want to do it, but I don't like riding it thinking the valves are going.

So if I change the oil and it goes away, I'll be a mighty happy guy!
Then I can wait till some better weather to change gaskets check valves and tune carbs.

I'll let you know! Thanks.

 

Oil weight may affect certain aspects of engine performance, etc. but not the valves. XJ engines have what amounts to "solid" lifters, not hydraulic lifters, and "lifter bleed down" only occurs in hydraulic lifters. Thus the viscosity of the oil will have zip-zero-zilch affect on the performance of the valvetrain.

Overly "tight" valves (meaning smaller-than-specified valve shim-to-camshaft lobe clearances) are a great way to destroy the cylinder head and/or the valves, get horrible gas mileage, make it impossible to tune up the engine, and lead to all sort of wild-goose-chases tracking down other "sources" of performance problems.

Besides a quick test-ride or two, the first thing I do to one of these bikes when I buy a used one is check the valve clearances, because I know that typically, no previous owner ever did........

"Just Say Yes!" to checking and adjusting your clearances.

 

Firstly, thanks for the input Chacal!
Good explanation.

Second, Fitzy, calm down lol!
This Saturday I will most likely be tearing down the valve cover, AND, my rear brake! Yay for me, and you! lol.

Third. HOLY CRAP IS THAT RICK!?

Ricky! Remember me? I sent you a PM but not sure if you got it.
I have that junk SECA that wouldn't tune, and was beat to hell.
Any chance I can come down sometime and have you go over some things on the bike with me? I could really use that sync of yours... I might be getting a colortune of my own for $15 soon.
How's the granddaughter?
Did you even sell that restored 700? (or was it 750?)
Hope to hear from you!

Also, thanks everyone. I will look into exhaust/vacuum leaks and the such.
But Wednesday afternoon I think I will be doing an oil change with better oil (for the weather AND the clutch)
Hope I can get down to Rick for a good thorough look through!
And I think I still owe him an oil cover... we drilled my SECA one to pieces... O_O

 

The Lifters in Yamaha XJ-Engines are:
SOLID LIFTERS
They do not have any Hydraulic Component.

The Valve Springs are covered with the a Cylindrical Bucket which holds the Valve Shim Disc which, according to its width, determines the close tolerance needed for the Engine to operate at High RPM's without "Valve Float" occurring.

Solid Lifters
No Hydraulic Issues

 

Umm, guys; Rick is spot on. '80s Honda Nighthawks (and a lot of cars) have hydraulic lifters that can bleed down; XJs are SOLID.

If you're going to be riding in real cold, then 10W40 would be a good choice, otherwise 20W40 or 20W50 REAL oil not synthetic, and no "fuel saving" (friction modified) oil.

+1 on the rear brake. Too many guys finding the same condition I found.

 

10w40 is actually what I used.
But it is regular auto oil, I think I need to go motorcycle.

Can't wait to show you a nice shiny non-delaminating drum shoe hehe
For safety reasons I hope it is.
Real scary stuff!

Rick, did you get my PM? I owe you an oil cover and I could use some help.
I also offered to Robert my assistance in moderating around here, have a good background in forum use and moderation and am online a LOT.

 

Thanks RickCoMatic, Chacal, and Fitz.... you learn somthing new everyday .... i was trying to find the lifter type to be able to see what type of lifter was originally installed.

You gotta love the engineers at yamaha for thinking ahead sometimes.