RGS Headache File

Garry

Garry

Junior member
Location
Eelde, Netherlands
The problem.
One cylinder regularly cuts out and the rev counter starts to fluctuate or drops to 0.
I suspect it’s the central cylinder, as that’s where the rev counter signal comes from (?) It’s not constant, but happens regularly. This occurs every time the engine reaches operating temperature, after about 35 to 40 km.
I’ve replaced the ignition system (now Sachse), renewed the wiring from the coils to the ignition module, and replaced the coils, coil leads and spark plug caps (now red NGK caps and leads) as well as the spark plugs (originally NGK, now Champion N3C). I’ve connected the module directly to the battery to rule out the ignition switch and kill switch. Replaced the earth cable and sanded down all earth connections.
Replaced all brass carburettor parts and adjusted and synchronised the floats correctly.
The battery is fine. 12.3 V with the lights on and 14.5 V with them off, both when cold and warm. I’ve connected the alternator wires directly, no longer via the light switch.
It runs perfectly until I’ve ridden for 35 to 40 km, alternating between gentle and fast riding.
I’m running out of ideas.
What else can I try? Does anyone have any suggestions?
 
I’ve just realised that if I connect the module directly to the battery, the kill switch still works🤦‍♂️… after all, the ignition coils are powered via the ignition switch through the kill switch… so let’s see how I can get round that.
(Thanks, AI Google 😇)
 
How frustrating.
Yes, as standard the centre coil provides the revcounter signal. So its flickering indicates that the coil supply/function is impaired.
Did the problem occur with the original BTZ ignition as well as the Sasche?
Another question. Where did you measure 12.3v and at what revs?
 
Garry said:
Measured on the battery at 3 to 4000 rpm.
It already had a DMC2 ignition system fitted. Same problem
Click to expand...
That's low for an RGS. I would expect little change lights off -> on at those revs .... certainly more than 14v. But regardless, DMC and Sasche will work happily at 12.3v. I wonder if you have a failing / failed reg/rect.

To bypass that possible issue, you need to disconnect the coil +12v supply from the kill switch (orange/white) and temporarily wire coils direct to battery. Bit of a PITA to stop the engine so leave the connection accessible! There is a connection you can break - leaves the kill switch supplied both sides but ignition off will fix that.

Sensor question by Hamish (The Sock) is a good one

connector.jpg
 
I’ve just done a test drive after connecting the ignition coils directly to the battery – unfortunately, no improvement…
When I come off the motorway after driving at 5000 rpm for a while, with occasional spikes up to 7500, the problem starts to occur near the exit when I ease off to around 3000 rpm.
The rev counter then starts to fluctuate again or drops to 0.
What’s frustrating is that it runs fine for a short while and then it doesn’t again… but it keeps stuttering until I get home. Once it’s cooled down, it runs perfectly again…
I’ve fitted a Motobatt MBTX 16U. Tomorrow I’m going to fit the one-year-old lead-acid battery.
I’ll let it cool down first and leave it in the corner for a bit…
 
Written before your latest update - good progress!


Okay. So you have replaced everything except the original RGS wiring. You've inspected and cleaned the earth's (including the one to the underneath of the battery tray?).

So that leaves battery (noting hooksey's comment) / charging; fusebox; ignition/kill switches and associated wiring. Given the issue is on one cylinder, that points to the section of orange/white wire under the tank that runs to the centre cylinder HT coil. Maybe check the aluminium mounting bracket is intact too.

For good measure, mebbe swop coil wiring between two cylinders (and the plug leads!) to see if the issue moves.
 
I'd also try disconnecting the green/red revcounter wire from the coil (think there's a bullet connector somewhere under the tank). That'll remove a potential wiring fault where it runs up to the instrument panel around the steering head.
 
"Shotgun" technique has a place, though does not identify the actual cause or most important, causes ( one fault can be two or more sources having the same or similar fault symptom ).

Worst of all you introduce "untested" new items into the process, which by combination may actually increase the pre condition of more faults or poor interaction between the introduced untested new parts, obscuring the original fault or faults. Very extensive process the op has embarked upon looking for the source of the problem.

On first read i thought of dark red motoplat coils, symptoms described to a T the well known demonic Motoplat ( there are two electrical configurations of red motoplat actually ). Pithy suggestion is to reinstall the pre fault condition ignition system and remove the unknowns, though this is less than ideal given the usual new parts can be better than old ones.

If me, would invoke a self test function in the "whatever" ignition that supports a full spark rate with motor off, and then look for the intermittent source of the problem. Tacho oem chip is less than ideal as an indicator of this problem, and can lead you to stay on one particular trail of no result, broaden your test procedure would have merit. Establish a stable known condition as a first principle in fault diagnosis.

Of course, could be fuel related...... dot dot dotting can be mischievous.....HTH j.
 
Hi, just a thought, is there any oil leaking into the pick up enclosure? Is the long filter thingy to the rev counter in place with all connections tight? Not sure if that's before or after the coil? If before take it off and see if it runs better?
 
Good idea about the pickup enclosure, but the sachse comes with fresh pickups, so…
Rob’s suggestions are gold. And as always Jono was on point, suggesting the possibility of more than one cause.
And don’t trust the tacho, well known teller of lies…
 
I’ve swapped the gel battery for a lead-acid one, and now I remember why I’d decided to go for the gel battery in the first place...
I was also inspecting the wiring harness and came across a forgotten two-pin earth plug in the cockpit that was quite badly corroded.
Could that???
At the same time, I’ll just tweak a few minor bits that weren’t quite to my liking anyway.
It’s Bloody hot here at the moment, so I’ll carry on tinkering with it next week.
 
My RGS had intermittent loss of spark on one at a certain rpm range and it only happened when I had the headlight on.

Long story short I had two problems. The first was only one of three circuits in the voltage regulator was working meaning lower voltage under load of headlight, combined with a broken spade connector at one of the coils. The plastic cover on the connector held the connector together. Combination of vibration caused a poor connection when the connector seperated and low current from headlight draw meant current didn't get thru the broken connector. With headlight off there was no problem.

Not sure this helps you other than perseverance and step by step process got me through it...eventually.
 
You must log in or register to reply here.
Back
Top