'83 1100E very hard starting, starter motor switching directions

[eldevigo]

My '83 1100E isn't starting up, and I'm trying to narrow down what might be involved.

I observed some weird behavior today while cranking it with the side cover off - the direction of the engine crankshaft occasionally flips in reverse for about a half a rotation before recovering and proceeding as expected. It's intermittent and irregular, and is accompanied by an angry metal slapping sound that I assume is from all the engine components changing direction suddenly.

My first thought is that the starter motor may be at fault, but I also checked for spark and the spark looks very weak to me.
While I was poking at it today I took off one pod filter and shot some starter fluid into it. This did get the one cylinder to fire a few times, but it was chugging pretty hard and would die very quickly.
Without starter fluid, no firing. I know this usually indicates a fuel issue, but I just cleaned and rebuilt all the carbs and I've confirmed that there's fuel in the bowls since reconnecting it.
It seems to me from the other available info that there are likely some electrical problems, so I'm wondering if they could be the cause of the failure to ignite as well. Is it possible that taking the pod off and shooting some starter fluid into the intake could be helping to address a weak spark issue?

I also noticed that there were puffs of intermittent backpressure through the carburetor that I could feel with my hand. I assume this is likely related to the crankshaft reversing issue.

I got the bike at the beginning of the summer in working shape (hard to start, but it ran), til it died on me a few weeks later on the road a quarter mile from home. It would crank but not start, as if it had a fuel issue. Since then I haven't been able to get it to fire up.
I took off, tore down, and rebuilt the carb rack, replaced the intake boots and the pod filters, tuned all the valves (they were all very tight, as if it hadn't been done in a while).
Before it stopped running I changed the oil and the plugs, and inspected the clutch pack for wear. I have never disconnected or adjusted the timing chain or removed any cams, so I don't think there are any major issues with timing - it's been on the same timing since the last time it was running.

While I was working on it today I had the battery connected to a 12v deep cycle marine battery with some jumper cables, I like to do this when I'm working on it so I don't run the bike battery down running the starter. Both the bike battery and the marine battery have been on a tender, and the starter has a healthy, lively sound when the marine battery is connected so I don't think it's likely to be a battery problem.
I also tested with the marine battery disconnected just for comparison - the starter doesn't crank as lively, but it still turns over as it should - the slapping and weak spark are unchanged though.

I have a short video of the signal generator showing the crankshaft reversing intermittently while cranking, and another one of the weak spark. I'm linking them here for reference.

Can anyone tell me if this looks like a bad spark to anyone else too, or if I'm being overly critical?
Also, can anyone tell me if this is somehow normal for the starter motor to flip-flop directions like this? Or if not (I can't imagine how it could be!) are there any obvious culprits that might cause this?

Crankshaft reversing: https://youtube.com/shorts/OXJZfIsNBK8?feature=share

Weak spark: https://youtube.com/shorts/bw78h_VfPLw?feature=share

[Grimly]

The 1100 engine is notorious for being overly sensitive to advanced timing, which results in it half-firing backwards.
You need to check the ignition timing next, before you do anything else. Buy a timing light.
There have been numerous tales on here of such incidents, with one owner even making a manual retardation lever to fit behind the mechanical advancer, so that the timing on startup would be retarded by a few degrees. This was even with the timing set at factory specs, it still needed that.
Needless to say, this habit can wreak havoc on starter clutches, cam chains, etc, if it's not sorted out.
Regarding the spark, if it's not a fat blue spark it's not optimal. An orange spark isn't any use.
Yours looks blue enough, but it might be no good under cylinder pressure.

[eldevigo]

Would timing issues cause this?
the video linked above is showing the crank being turned by the starter motor, no ignition involved. I didn't see any indication that the ignition timing was firing backwards, though to be fair I can barely get it to fire at all at the moment.

[rphillips]

If you have access to a non resistor spark plug, stick it on a plug wire and see if spark looks better. If no noticeable difference, forget it,.. I know everybody knows that's crazy, but a couple yrs. back I couldn't get my GSX1100G to hit a lick after it's winter nap. Like you had a tiny spark, hardly visible. Tried all I could think of with no luck. Noticed a D8EA non resistor sitting on the shelf from my GS1100 and figured I had nothing to lose. I plugged that non resistor in a plug wire and immediately saw a big bright blue spark. install all 4 D8EA non resistor plugs and she fired right up. Not supposed to happen but did pretty simple to try. If you see no difference when you try 1 non resistor plug on one plug wire, no need to fool with the other 3.

[oldGSfan]

You can search on "starter clutch" and will find a bunch of theories. The basics as I understand it are: The clank (which many are familiar with) is the starter clutch internal ball/spring/roller (https://www.partzilla.com/catalog/su...starter-clutch) being roughed up when it reverses.

It reverses due to the occasional positioning at just the right place (before TDC) where the starter won't spin the motor up fast enough to provide enough inertia to overcome the cylinder firing and it sends the piston back downward. So logically it could also be a timing issue - if someone puts the chain one tooth out of whack, I imagine it could exacerbate this. The chain timing is detailed in the manual. In my experience, it can also be very dependent on how good your battery and starter are.

One change, which I did, was to rig up the 'Run' (kill) switch to allow you to spin the motor with the start button depressed and key on, then flick the switch to 'Run'. More on that below.

You may also want to look up the coil relay fix, which gives direct voltage to the coils rather than the circuitous route of the stock wiring, which goes through the handlebar switch. https://gsarchive.bwringer.com/bikec...relay_mod.html

I took apart my starter clutch and found no damage, but it was doing the 'clank'. With a new battery, it has been perfect for many starts. I wonder if the battery you are using has enough CCA? It really needs to give the engine a good spin. My bike starts immediately, cold or hot (with a bit of choke when cold, for just a few seconds). It fires faster than my son's 2022 Tenere, but maybe that's due to having more cylinders (4 vs 2).

Aftermarket ignitions (Dyna) seem to have an electronic ignition retard, whereas stock doesn't. This jibes with my experience, I have had a few GS's with Dyna and never had the 'clank' of the starter clutch (reversal of direction), but with stock, I have experienced it on a few bikes. I don't use the bypass of the kill switch, as I now never have the issue. I believe installing a fresh battery with >200 CCA, and the coil mod has fixed it completely.

Search around on the coil mod and the starter clutch. Check timing, make sure not one tooth off. Check the battery is really giving that motor a good spin. That's my .05.

[Big T]

Things to check:
Ignition timing
Cam timing
Voltage at coils
Did you follow the carb cleaning tutorial? It would appear you didn't, rebuilt?

[eldevigo]

I believe CCA is not the issue, just from the response I get from the starter motor when I hit the start. Even if the bike battery were sagging below the required amperage, the marine battery I had hooked up in parallel should have been plenty, it's a little old but its rated at 845 MCA, which I believe is in the range of 630 CCA. It spins up that motor faster than my 2014 vstrom and the 1980 honda twin I have in the parking lot, but it doesn't stop the reversing issue.

I also don't hear any indication that the engine is firing at all at the moment, unless I hit it with starter fluid. The carb bowls are wet, and everything's been run through an ultrasonic bath with a carb cleaner/degreaser solution, but it's possible they aren't feeding fuel to the engine properly still.
If they are, then there's something wrong with the ignition, and since it hasn't been adjusted at all since the last time the bike was riding and driveable, I don't think the ignition timing could be all *that* badly out of sync.
My best guess at this point is that it's either carbs or spark. I don't think either of those things would cause the spinning backwards issue though, so my guess is that's a separate issue.

I did follow the carb rebuild tutorial here:

https://gsarchive.bwringer.com/mtsac/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf

it's probably exaggerating to call it a rebuild, i just disassembled/cleaned, and replaced o-rings, intake boots, and air pods. the float and jet needles and diaphragms all looked like they were in great shape, no notching or visible wear, so I didn't bother to replace any of them.
I skipped the wet fuel level test on account of I don't have the tubing or a bench vise to make this easy, but I did set the float height to the factory spec on each carb with a pair of calipers before reassembling it.

As mentioned I'm doubtful that the ignition timing could be so badly off that it's causing the engine not to fire, but I didn't check to confirm that the cam chain alignment is correct and i wouldn't be too surprised to learn that the previous owner might have tweaked it enough that it could be causing poor performance and contributing to hard starting. He obviously rode this bike pretty hard on a track, and didn't seem to care too much about trying to preserve its stock look or original engineering specifications.
I'll open up the valve cover and check it against the service manual next time the weather is good.
My understanding is that there's no other timing adjustments on this bike, is that correct?
I don't know a lot about timing control systems, but my understanding is that the mechanism at the end of the crankshaft is a signal generator and a dynamic timing advance that kicks in at higher RPM, but isn't statically adjustable (without some monkey-wrenching aftermarket modifications). I'm not sure where else someone could mess with the timing other than by changing the cam chain alignment. Is there anything I'm missing?

On the matter of voltage, I'll try a no-resist plug to see how it behaves, and I may look into that coil relay mod. I'll check the voltage at the coils as well.

Thanks for all the advice!

[Redman]

For the weak spark: Check voltage at the coils, before cranking, and during cranking. Report here.