#2 Cylinder Not Firing?

[NotSoLilCrippseys]

My son and I are into another GL, a '78 this time. We're looking for a relatively straightforward turnaround on a bike that was well cared for - until it wasn't a few years ago. (I should have started a build thread but haven't.)

We're working through it and after sorting out new points/condensers and setting that up, we've got spark at all 4 plugs. Carb rack is off my '79 GL, which I know works quite well. It carried me 300 miles the day before I pulled it as a temporary donor for the '78. We should mostly have the makings of a runner.

Last night, she came to life and ran - like crap, and mostly only with an ether shot.

Brief digression - After a couple more hours poking around today, I find I may have a bad donor/replacement fuel pump, which seems to be starving the motor. Reattached my gravity fuel cell directly to carbs (with inline filter) and got her running really, truly rough.

For a few minutes, it seemed I had no bang in the left bank - #2 and #4 (cold headers). Then #4 woke up a bit and she ran a bit better. #1 and #3 quickly got burn-the-fingers-hot at the header. No dice on #2. (I know I have spark. I know I have a good carb rack.) I have yet to adjust valves, but I did pull the cover and nothing is obviously bad there. Valves have a little gap - even when warm. No point measuring until they're dead cold.

#2 could have no real compression. I don't know yet but have no good reason to think there's a problem in that area. 50k. Well-maintained bike - for most of 40 years.

What else might cause a no fire issue in just one cylinder?

No signs of head gasket issue on that side - no coolant in old drained oil, or vice versa. The smoke out the exhaust is not steamy, sweet coolant-like.

Its coil mate seems to fire just fine, and both #1 and #2 have decent spark. (New plugs as well)

Maybe #2 wakes up with another 20-minute, smokey run? Maybe I'm missing something obvious?

#2 is pretty far from the fuel line port. Could gravity feed not be good enough to get fuel all the way over into those bowls? I think the pump runs something like 3psi. I'd welcome that as the source of the issue.

[ritalz]

If you can verify fuel to #2, I would try swapping plug wires from 1 to 2. With the wasted spark system both should fire. That would verify that both wires and caps are good.

[gltriker]

my 2 cents...all 4 cylinders' compression test number hasn't been checked yet?

set all 8 valves' cold lash clearance at 0.006". Observe any significant deviation of valve lash clearance on either #2 cylinder valves?
Perform a complete cylinder compression test session. Fully opened throttle, Continue cranking until the needle won't advance any higher on the tester gauge face.

[redglbx]

Several things, as Cliff noted check the compression, but it may be a bit low from sitting and it will probably come up some with use. Keep an eye on the valve lash as I had problems with my LTD where the lash kept closing up as I rode it, so I got to where I checked the lash after each ride and readjusted it until it stabilized, the .006in lash isn’t a bad thing at least for a while until you get some miles on it.

Also, you need to check the plug caps which should ohm across them at less than 5k ohms , I personally have gone to just eliminating the resistor in the cap replacing them with a piece of brass or copper or a 10-32 screw piece will work and then just use resistor plugs which give you the same effect and get refreshed with each plug change. But check the caps you have to start with.

Check that your coils are not cracked, run the bike in the dark to see if you get any blue arcing,, it shouldn’t !

Check the gas tank pickups for heavy rust, you’ve ran it with an external bottle so that shouldn’t really matter.

Is this bike running the stock points and condenser or a Dyna setup ?

[NotSoLilCrippseys]

Thanks.

Stock points - freshly installed, gapped, and timed, with new condensors. I have good spark at each plug. There's no indication of cracks in the coils, but I've not to run that awful sounding machine in darkness to look for arcing.

I'll be setting valve lash before I fire her next, but I don't think that's going to be the issue.

Reading Randakk recently on at least the early (GL1000) carbs, I see that fuel gets to 1&3 before starting to fill 2&4 bowls. This information aligns pretty well with the experience I had: Firing on 1 & 3, with hot header, while 2 &4 are lazy and cold. Then 4 fires and heats up, the bike runs a little better.

After a 400 mile ride on Sunday, with plenty of meditation time on the super slab, I think I need to confirm the fuel pump actually works. I have a new one in a box from the PO - as the one on the bike was a fuel-stained mess. But I had what I thought was a functioning old one.

I hear you on compression. I don't have tester that'll fit the plug holes, or I'd have done that straight away.

I know. Compression is a good guide to the overall health of the motor. Not knowing is not knowing. And all reports say that compression goes up - often - once these bikes get some exercise and rings clean up as the crud works its way out. I'll buy one if I can't get this sorted - no point in chasing a motor that'll only run on 3 cylinders.

I'll report out once I've done a bit more tinkering.

[redglbx]

Check the plug caps resistance ! You can have spark with a substandard cap that causes all kinds of issues. They should be less than 5k ohms but I’ve seen some with close to 10k ohms that ran but had all kinds of erratic operation !

[NotSoLilCrippseys]

I have more info to share.

Unfortunately, it points to a carb rack that I know was well functioning on the day I pulled it from a running bike and moved it to this project as a temporary donor. (All I did in that migration process was pull the slides to polish them a bit, hoping I'd smooth out the throttle response a bit.)

Here goes:

• We adjusted the valves to .006 across the board. Most were a teensy bit tight, but that's probably because the manual calls for .004 and .005. Timing is spot on, with points with the right gap and well timed.

• We got #2 to fire intermittently last night. #4 is also lazy to get rolling. That's not good.

• We did find loose plug caps on the #2 and #4 wires, and we snipped the ends and reattached the caps. Some improvement, but firing is sporadic on the left bank. #2 seemed to heat up more than #4. We did run to nearly the point of fan activation, but it was late, the noise was bad for the neighbors, and the smoke wasn't so cool for the community (or us) on a heavy, rain/fog evening.

• Today, I swapped the wires from 1&2 and 3&4. If I've got a wire issue in the #2 wire, it would migrate over to cylinder 1. Nope. 1&3 still fire right up; 2&4 remain lazier. Last night, I was still pushing a "spark" theory with my son; today, I'm not.

• I bit the small bullet and picked up a decent screw-in compression tester after work. Results show a healthy motor: 160, 170, 160, 160 - 1, 2, 3, 4. I double checked 2 &4 after I finished with 1&3. It's consistent. Throttle was wide open; no choke; good, charged battery; healthily cranking starter; all plugs removed. I read Randakk on compression in GL1000s, and 160s is a good zone, especially for a bike that's been out of service for more than a few years. This motor is probably good the long haul - once it's sorted a bit.

So: Spark is known good, and I even did the switcheroo just to confirm. Compression is good. Timing is good. And then there's fuel.

My son says, "OK. I guess the carbs have to come out." Woo hoo - not.

Why not just bolt up the '79 rack? It came in a half-disassembled pile in a plastic bin. So disappointing! I started cleaning/rebuilding, but it's missing a couple necessary bits - one spring, one white plastic washer/spacer for a slide cover. It might need more bits. I hope not.

[gltriker]

snip-
...... a carb rack that I know was well functioning on the day I pulled it from a running bike and moved it to this project as a temporary donor. (All I did in that migration process was pull the slides to polish them a bit, hoping I'd smooth out the throttle response a bit.)

Spark is known good, and I even did the switcheroo just to confirm. Compression is good. Timing is good. And then along came gltriker

Set all 4 carburetors' air/fuel pilot screw at 3 full turns out from lightly seated , and hook up your Carbtune Pro synchronizer set now, as well.
Don't roll your eyes. Humor me please.
Utilizing the Carbtune Pro as a troubleshooting tool, you may discover something is still amiss. Intake manifold air leaks? New orings were utilized? You have full confidence the fuel is Fresh and not of questionable quality. <<<< (my trike's engine loathed it AND the less than new intake manifold orings)
Be sure to tighten all 4 intake manifold band clamps, again, while they have been heated up to full operating temperature.

Although the well functioning carb rack functioned well on the donor bike, this new project bike's engine may not be equally satisfied with the donor engine's previous idle speed synchronization linkages adjustment results, too. maybe yes...maybe no.

Wouldn't it be a kick if the testing carb rack's donating engine is not as equally sound as this new project bike's engine has been dynamically measured to be, with your newly acquired cylinder compression testing kit

[NotSoLilCrippseys]

Cliff. Thanks.

Dynamic sync for one machine may not be sync for another. Good point. I had figured I'd be "close enough" for firing on 4 reliably given how well the rack works on the donor. (I've swapped a GL1100 rack across 3 different bikes for testing purposes; it's been just fine for that purpose. I wasn't imagining the GL1000 would be that different.)

Screws are out 3 turns, for sure.

I can hook up the Carbtune easily enough to see how far off I am on the sync - and adjust. Intake o-rings are 1000 miles new and on good, and intake clamps are tight. Both can be double-checked.

All that's good "have a look-see" advice that can be taken before I do a more labor-intensive thing than pulling the rack to clean jets.

2 weeks ago, I had non-working points/condenser. Last week, I had good points and still no spark. By the weekend, I had good spark. I'm inching closer.

And you're right about feeling the need to test compression on all my bikes - because I can!

I suppose I should share a fun photo of this '78 we picked up.

PXL_20230525_121405557.jpg

Yup. That's the original headlight and bucket - complete.

[NotSoLilCrippseys]

OK. Done for the night.

• As I couldn't get to a stable idle, I couldn't do any meaningful check of carb sync - I tried.

• Intake clamps were tight, o-rings were not pinched.

I pulled the rack and got elbow deep, as "known clean carbs" turned out to be false.

Big lesson for me: Beware old fuel pumps. I'm not running off the fuel tank - which is actually pretty clean and rust free. And I'm running a good filter between my external tank and the pump.

I had crap accumulated in the bottom of all 4 bowls. More disturbingly, the tiny fuel screens were chock full of sediment/crap. I mean full. I've been in 4 or 5 GL racks and never seen that much sediment in/on the screens. Wow. The jets were clean, which I suppose is something. I pulled apart the bits, cleaned, and reassembled.

I think the bike ran ok for about a minute. Both headers were heating up and at each exhaust port, so that's progress. But #2 was still super uneven and then seemed to kick the bucket. #4 might possibly more lazy than 1 & 3. I thought they might roar to life once fuel made its way all the way over there and into the bowls. Alas.

I pulled plug #2. No change in RPM, engine behavior. I pulled #4, and I went down to 2 cylinders. I pulled #1 - same effect. I pulled #3. Ditto. #2 is doing a number 2.

I'll pull the rack again, get under the bowls, and have another look. The jets were not clogged. My issues seem to involve a problem getting fuel into #2. The one thing I thought I was counting on to be solid - the carb rack - is the weak link. I'll have to get in more than elbow deep.

Will a GL1100 rack be mostly plug and play with a GL1000 for purposes of garage testing? I have one of those on the shelf, and it recently brought a seemingly dead engine to life.

[gltriker]

OK. Done for the night.

Will a GL1100 rack be mostly plug and play with a GL1000 for purposes of garage testing? I have one of those on the shelf, and it recently brought a seemingly dead engine to life.

Although I have never needed to try the GL1000 -GL1100 carburetor swap over, I've read YES, many others have; mainly, to gain the benefit of the GL1100 carburetor "rack" accelerator pump feature.

[Rat]

The 1100 carbs should work just fine …

Gord(been there, done that, didn’t get a t shirt)Jones

[NotSoLilCrippseys]

Thanks for confirming the 1100 rack will work.

I've been incommunicado and away from the bikes for a bit. I think this tech thread has reached its logical conclusion.

I pulled the rack again this evening. Definitely a clogged fuel pathway into the #2 carb. So that's good news because it's a clear finding. I disassembled again and made sure I have good flow through to all 4 carbs, using air and making sure to focus on getting #2 as free-flowing as the other 3. I also flushed a bit with carb cleaner and dried it with air.

I'm not putting that rack back on the build, as I really want to be riding Ginger. 18 months of labor; I think I've earned some time in that saddle.