XJ Inconsistent Idle

[Smash]

Is an inconsistent idle on an XJ11 caused by the carbs being out of sync? I have not tried riding the bike with the YICS eliminator installed.

[CatatonicBug]

Though I don't know for certain, it stands to reason that makes sense. The YICS tries to balance the vacuum between all 4 carbs. It's amazing how performance improves with a proper sync. Get the eliminator and get the carbs sync'd. Then, diagnose other problems.

[DGXSER]

I recently posted how incredible the difference can be in re-shimming the valves, synching, tuning, and re-synching the carbs. The difference was night and day for me!!

So short answer is, yes, it most definitely could be.

[jetmechmarty]

Valve clearance out of tolerance could show up as bad idle too, as was just pointed out.

[Smash]

Hoping it's the carb sync, will get on that.

If it's the valve clearances I'll probably throw in the damn towel. That work is beyond me (I've helped a few times on Honda V4 engines).

[natemoen]

Hoping it's the carb sync, will get on that.

If it's the valve clearances I'll probably throw in the damn towel. That work is beyond me (I've helped a few times on Honda V4 engines).

Valve shim are real easy on these.

[Smash]

Thanks! I just read over the valve check procedure in the manual, it unfortunately doesn't seem easy at all to me! Dealing with the timing/cam chain is what scares the heck outta me. So, here's to hoping the carb sync will sort this out.

On a good note, everything else on the bike is working as it should. I'm getting a battery warning on the dash, even though the fluid level and charging system is testing correctly. Need to look up and see what that is. It's just the idle/slight backfiring left to sort out.

[DGXSER]

Be brave young fella, you and that bright philly of yours can easily acomplish the valves.

Here is what I recommend as the process, used it myself.

Put bike on centerstand

Remove seat and tank, followed by horns, Pull the plug wires and hook or tie them up to the fram out of the way, and then remove the valve cover. I also pulled the throttle cable out, left it hanging from the right grip.

remove the left hand side engine cover/timing cover. Put a 6MM socket in the center bolt to turn the crankshaft with. Always turn the crank clockwise when looking at it from the left side, or alwaus turn the top of the timing plate toward the rear of the bike. Using feeler gages, check and write down all the clearances in all the valves. I make a table to record initial gap, initial shim, new shim, new gap. One row for each intake and each exhaust. If all are in spec, revers the removal process and enjoy. If some need adjusting, read on.

Now turn the engine to the C mark on the crank, and make note with pictures or mentally where the dots are compared to the arrows on the center cam chain caps. Now remove the cam chain tensioner. (I know this seems like voodoo black magic after all the horor stories you can read about on here, but man-up all will be ok, really). This puts the slack in the cam chain to allow the cams to lift up.

Now, shove a towel or two down in the cam chain galley to keep any stray parts out of it. Remove all of the cam cap nuts and washers from one cam, no need to remove the caps though. Use a screw driver under the cam on a unmachined surface to lift one end up and you can pull the shims out one at a time from each valve and record the existing shim size. Repeat for all four valves on that cam, and then replace all the cap nuts and washers, no need to tighten or torque just yet. Now repeat for the other cam.

Now you have the existing gaps and shims. This will let you use a chart or calculate what size shim you need for any that are out of spec. Get the correct shims to replace the ones needed.

Now repeat the process for removing cam cap nuts and washers and replace the shims needed. As you finish one cam, use a criss cross (figure eight) pattern from the center out to torque the nuts down. (No manual stipulates this, but I consider it good practice and it can do no harm). Repeat for the other cam.

Now, this is where I take a wrench on the cams, there is a place machined into the cams for a wrench to turn them. I start with the intake cam, while holding or at least watching the crank so it does not turn, and turn the cam as much as it will with gentle pressure to remove any slack from the back side of the chain. I repeat this for the exhaust cam, so all the slack is back on the front side of the cam chain.

Now replace the cam chain tensioner, look at the dots on the cams and see that they are in the same place as when you started, and the C is line dup with the pointer on the timing plate. Assuming all this is correct, turn the engine over a 3 or 4 times by hand, stop at the T mark and make sure the dots are properly lined up on the cams.

From here, just replace the covers and parts in reverse order. It is not very tough to do.

[CaptonZap]

Hoping it's the carb sync, will get on that.

If it's the valve clearances I'll probably throw in the damn towel. That work is beyond me (I've helped a few times on Honda V4 engines).

Don't fret, if it turns out to need done, I'll come show you how. Get some feeler gages and measure all the clearances, in inches, i.e. .00whatever, and write them down. If you don't know how to do it, I'll call you and explain.
Let me know what you have. CZ

[SFerinTEXAS]

Stop hoping and just do what needs to be done. You can do it.

[Smash]

Whew the carb sync helped A LOT. She takes a little while to get warmed up but it's significantly better.

We'll do another carb sync to fine tune as I was out of town last weekend (she rode with a friend to get the hang of the bike).

Have the YICS eliminator still in there, might pull that too and see what it does cause I'm curious. Can always just put it back in.

[Smash]

Don't fret, if it turns out to need done, I'll come show you how. Get some feeler gages and measure all the clearances, in inches, i.e. .00whatever, and write them down. If you don't know how to do it, I'll call you and explain.
Let me know what you have. CZ

Thanks!

Idle is still fishing a little, so we'll do another sync and see if that helps again. I know we didn't get it great with the last sync, just closer to better!

[Smash]

Hey guys....

Could this inconsistent idle be caused by bad diaphrams?? I remember noting they were getting a little stiff when I was in there. No cracks or leaking, just getting stiff. Assuming they are the originals.

[Smash]

Yeah you guys are right, I'm just wishing it wasn't so.

Ugh, called the local shop we use occasionally, and even with a reasonable shop rate ($66/hr) we're still looking at $270 or so for the valve check/adjustment depending on # of shims needed.

[DGXSER]

All it cost to do it yourself is some black RTV gasket material, and typically about $20 at most in shims. The shop probably has a pluthera of old ones laying around and would simply swap with yours and still charge you.

Tell Karla it is not that hard and just get it over with next rainy weekend.