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Not firing on all cylinders after a valve adjustment...

fastenova

Member
Member
Hey all,

Just finished up a valve adjustment on my 2011 C14, 31K miles. I've done valve adjustments on several other bikes (and cars) without issue, so I'm not too green, but that doesn't mean I can't make a simple mistake, so please don't hesitate to run the most basic of ideas past me. Here's the skinny:

Bike ran great prior to tearing into it, but AFAIK the valves hadn't ever been checked. Did a valve adjustment. Was very careful when measuring clearances and verifying shim thickness, and re-measured on all valves after swapping shims to verify correct clearances now exist. I was also quite meticulous about setting the timing, and rotated the engine several revolutions after reinstalling the CCT to make sure everything was lined up before putting the valve cover back on. I've got it all reassembled, except for plastics. Worth noting that I also replaced the exhaust header nuts with locking flange nuts, one nut at a time... so that "shouldn't" have affected anything but worth mentioning. All new spark plugs and gaskets were used, including new o-rings on the cam sensors.

I fired the bike up and was 'lopey', almost sounding like a v-twin. I let it idle for about 5 seconds but no change. Feeling the headers, 1+2 were hot, 3 was 'warm' and 4 was cold. To be honest, I could not tell if 3 was firing or was just warm from the adjacent cylinder.

I didn't touch the fuel system at all. I am (at this point) fairly confident that I got timing correct as I marked both the cams and camchain before removing, and didn't rotate the engine at all while the cams were out, plus rechecked timing as I said above. So, I think it is more than likely either a spark issue or an air issue (going to verify the air suction valve covers are torqued).

I'm going to go down to the garage and start tearing it apart, but wanted to toss this out there to see what ideas y'all had to check. I've already verified the plug coils are all fully plugged in but will likely pull them all out, recheck spark plug torque and make sure they're fully seated. I am also not sure I installed the plug coil subharness per the FSM, underneath the intake cam sensor wiring, so I'll check that and fix if needed. Finally, I may swap the plug on cylinder #4 just in case I got a bad one from the factory.

Any and all ideas welcome! If checking all the above (plus any ideas you all can throw my way) don't solve it, I'll do a compression test to be 100% sure my timing is spot on.

Thanks for your input!
Aaron
 
Boom goes the dynamite! Yep, I had 3 and 4 plug coil leads swapped. I didn't think about this at all... for whatever reason when I installed it I remember looking at the harness and thinking, "This can only go one way" and it looked to me like the lead length difference was obvious... I guess not! I swapped them and she purred right up. Going to reinstall the subframe and get it warmed up.

THANK YOU @laker9142 for the quick response and super accurate guess!
 
Boom goes the dynamite! Yep, I had 3 and 4 plug coil leads swapped. I didn't think about this at all... for whatever reason when I installed it I remember looking at the harness and thinking, "This can only go one way" and it looked to me like the lead length difference was obvious... I guess not! I swapped them and she purred right up. Going to reinstall the subframe and get it warmed up.

THANK YOU @laker9142 for the quick response and super accurate guess!
Glad you figured it out and an easy fix.
 
All i can add is take lots of pictures... next time i do mine, ill be numbering the coil paks ...
I think I took about 30-40 pictures with my cell phone as I was disassembling it all, thinking I was overdoing it, but I obviously did not take enough! Next time I disassemble, I'll use my digital camera and take way more photos. I had a couple of wire/hose routing decisions to make that I was not sure of the best layout, and ended up referencing the FSM for those. Doesn't help that PO changed spark plugs at some point and left things a bit of a mess.
 
I think I took about 30-40 pictures with my cell phone as I was disassembling it all, thinking I was overdoing it, but I obviously did not take enough! Next time I disassemble, I'll use my digital camera and take way more photos. I had a couple of wire/hose routing decisions to make that I was not sure of the best layout, and ended up referencing the FSM for those. Doesn't help that PO changed spark plugs at some point and left things a bit of a mess.
The PO piece can haunt you, especially if routing was changed, wiring has a good memory but once redirected can be a bit hard for all to fall in place.

For these items that share like connectors in close proximity (ignition connectors) tape on each identifying cylinder # can prevent some headaches for sure.

On the right side of the machine, don’t recall the sensors this moment, there are two sensors of which will cross plug-in. KAWA dealt with that by coloring the hardware.
 
I spent a couple of hours (!!!) syncing the TBs while I have everything apart, because the bike had a bit of a wandering idle when cold. It never felt like it was going to stall, but it is a bit annoying and is generally a symptom of unbalanced carbs/TBs. While I had everything apart for the shim job, I ran silicone vacuum hoses from each TB to the left side of the bike and capped them for ease of syncing.

What a freaking pain! The 'bypass screw' on each TB is obvious, though #4 is hard to get to due to the electrical connector right there, I ended up detaching it and slightly bending the bracket out of the way. And the center linkage adjusting screw is a nightmare to get to, even with the right tools, because you can't see it! Using a mirror and all of my patience, I was finally able to get it dialed in but this process took way too long IMO. I just sync'd my parallel twin 700 (took all of 3 minutes) and sync the 4 carbs on my old XJ650 yearly (about 15 minutes, including popping the fuel tank). If they had made the linkage just a little bit longer so you could actually see the screw, that would have shaved an hour off the job, easy.

We'll see tomorrow if this solved the idle issue, but I'm guessing it will based on how far off cylinder #4 was...

Before throttle sync:
1643090610321.png

and after sync...
1643090666618.png

Crazy how much more vacuum they're pulling when they're properly synced. Idle is the same speed (~1150) in both photos (I adjusted it down twice during the sync process).
 
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Also the valves closing for proper duration has improved both vacuum and compression - this will play no small part in improved performance idle through WOT.

I assuming both before / after photos are post the valve adjustment, would’ve been interesting to see before sync prior to adjustment.

I predict you’ll be quite pleased!
 
Also the valves closing for proper duration has improved both vacuum and compression - this will play no small part in improved performance idle through WOT.

I assuming both before / after photos are post the valve adjustment, would’ve been interesting to see before sync prior to adjustment.

I predict you’ll be quite pleased!
Agreed, since almost all of my valves were tight (15/16)! I am expecting smoother running and a very slight bump in performance under load and fuel economy. Add in the sync so all cylinders are pulling their fair share, and it should be much improved overall. Now if only it was a little warmer out so I could have a nice long ride to feel it out... Had freezing fog yesterday and it's about 35* out now.

And you're correct, I didn't check vacuum prior to the valve job as I didn't have the lines run, but it would have been neat to see those numbers too. I guess I'll get the opportunity again in another 20-30K ;)
 
Update, I took the bike out for a ~80 mile ride through the farmland on some rural highways, and it ran fantastic! I think the valve adjustment gave me just a little more power, and the sync definitely made a positive difference in the overall smoothness and the idle stability. Well worth the time and effort required!
 
FYI, throttle sync should be done at 1,000 rpm. Then you return the idle speed back to 1,100 when your done. The manual also advises you to use a more accurate external tach connected to one of the stick coils, not the one on the bike.
 
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