Trying to get beloved Sport back on the road- poor idling

[Long_Road]

Sorry you are right - a blue spark is good. However they do seem quite faint, and the rear is dancing around too much for my liking. I just wonder if under compression the spark is struggling.

I purchased NGK BP7 ESs from NLM so reckon they are good. I may consider the race plugs if they help matters too. Going to have a look on Vehicle Wiring Products for some lower-resistance caps, and maybe some new HT lead as well.

I'll also be testing the stator next. Many thanks for your help chaps, I'm learning a lot.

[Long_Road]

I'm getting 77-79 volts AC at idle. The multimeter doesn't want to give me a resistance reading for some reason. I will still fit some low-resistance plug caps if I can but otherwise I think I have travelled far enough up this avenue.

I went for a 2 minute test ride and she seems to be running well - pulling strongly with good throttle response. I only took the revs to 5k because I'm running in. Idle had risen to 2k when I stopped. Hmm. I have some spare carb bodies I am going to try just to see if there is any difference.

The timing is still set very far advanced (at the ANT mark at idle). This is something I need to look into.

[norbert]

First you have to put valves and ignicion the right way. Before doing this it makes no sense playing with the carbs. If you have the ANT mark at idle revs where it should be at 6000 revs you may melt your pistons doing a longer testride at higher revs!

norbert

[Long_Road]

Norbert - you are correct. This is next on my list.

[Long_Road]

I have set the timing with a timing light to correct specification, and the timing is hitting all the marks - just above PMS at idle, advancing to ANT at maximum advance. I also marked up the flywheel so I could check timing on the rear cylinder and all was spot on.

She will idle for 10 seconds at best, then slows to a halt. Initial throttle response seems not as good as before but once the revs are up above 2k she seems to run as well as before (haven't had a ride yet). It feels like the timing is off at low revs, but the timing light tells otherwise. It's like it's continuing to retard as the revs settle.

I got it to run quite well with carb setup when the timing was set 34 degrees too advanced. This would indicate to me that the carburation is not far off, whereas the ignition system is.

I'm considering an NLM ignition setup, but I would really like to know why there is an issue rather than just remove and replace.

Apologies if I'm boring you guys.

[MickeyMoto]

Just a quick thought. Is the flywheel correct? Early bikes were timed at a different point to the later ones and had a different flywheel, I believe.

[72degrees]

Just a quick thought. Is the flywheel correct? Early bikes were timed at a different point to the later ones and had a different flywheel, I believe.

It does make you wonder. The flywheel on my 'racer' certainly already has an ANT.2 as well as an ANT.1 mark. No need for extra marking up to check the rear cylinder timing on the early ones. The later ones only have an 'ANT' mark as far as I can see from the 'blue book'. The photo of Chris's Sport shows a side cover with no 'window and plug' for checking the timing against the camshaft axis. Then who knows exactly what came out of the factory in the late 70's period when the cast wheels and then the electric start (option?) were introduced?

[72degrees]

I just checked the rotor and stator that came off the 1977 350 engine that I rebuilt (the stator needs rewinding so I used the ones from the donor 250). Clearly marked with ANT.1 and ANT.2. This Sport is a '77' but has it got it's original engine? Presumably using a rotor marked with just ANT is not an issue if you check the timing against the camshaft axis, not the crankcase mark that my 77 engine certainly has? Are the PMS marks also in different locations on the later rotor? It's a long time since I had my 1979 electric start Sport - so I don't remember. Checking them with a probe through a plug hole is easy enough.

[Long_Road]

An incorrect flywheel has crossed my mind, I guess with Moto Morini being a small factory means all their bikes were something of a unique mix of old and new models. I’m not suggesting they got it wrong in my case, more that it makes it tricky to ID the definite setup for a given year.

My flywheel does indeed have a PMS.2 stamped on as well as PMS.1 and ANT.1, I marked up an ANT.2 with a permanent pen. The punch mark for timing is in the 9 o’clock position, and all the timing marks align when the pickup is positioned with the moulded arrow pointing to the line in the pickup’s housing. In other words, the timing is spot on. I will check the actual TDC positions and also take a couple of photos shortly – bear with me.

Thanks for your continued brain storming.

[norbert]

The older models have the mark for timing PMS and ANT at 9 o clock.

Then the mark changed to the center of the camshaft axis at 12 o clock (guess it came with the electric starter. From then on all the motors were prepared like this although in the first years the electric starter was en extra that must be paid, For that reason some came out of factory prepared for the electric start but without starter) Theese flywheels have the air shovels.
All flywheels have the marks PMS 1,PMS 2 and ANT 1.

The flywheels with all the marks ANT 1 and ANT 2 for 350 and 500 are the last generation before coming up the Kokussan that are suposed to have the strongest magnets. As far as I know you find them for example in the Enduros X3 and Excalibur 350/501 and Camel 501 before they changed to Kokussan.

[Long_Road]

Checked TDC for the front cylinder and it lines up with PMS.1. This is the flywheel, just for identity's sake:

DPP_0004.JPG (158.65 KiB) Viewed 12595 times

PMS.2 stamp:

DPP_0005.JPG (125.52 KiB) Viewed 12595 times

Ignition pickup, note the alignment of arrow to line:

DPP_0007.JPG (180.22 KiB) Viewed 12595 times

[72degrees]

That's interesting. Reading the blue book again I see that it confused me and that they all had an ANT.1 not just ANT. I just had to go and look at my two to remind me just what they have. The 375 has a three air slot rotor, without electric start drum, marked with just ANT.1 - though the 1 is pretty faint. I'm sure it's not the original rotor from the 76 engine though as that was of the two peg holes variety when I first had it. The racer has the rotor that came on the 1982 (Spanish market) 250. That is a three slot (non electric start) one but definitely has ANT.1 and ANT'.2 marks. I already knew that, because I spent ages recently checking the timing on the NLM performance pickup to get it spot on for both cylinders. Naturally, that could also be a replacement not the original.

Both these 350 engines (76 and 77) have the punch mark on the crankcase and when strobed, that's where the ANT.1 mark (and ANT.2 on the racer) line up with and advance correctly when they hit 6000. Which seems odd if these late rotors were designed to be strobed against the camshaft axis - or were they?

Chris's definitely looks to be an early 2 peg hole rotor with only an ANT.1 mark so should be the correct one to be timed against the crankcase mark not the cam.

So why the ignition advance is seemingly out is still a mystery. I forget - does it definitely have black transducers with green dots to match the red pickup - not later grey ones?

[norbert]

The rotor of the pickup looks like the very first one.
There are two kind of red pickups! Maybe that you have the second generation of red pickup in combination with the first generation rotor? The difernce can be seen if you compare the length of the visible metalic parts (don´t have the right word ) inside the pickup. Right now I don´t remember the right measure of each, but maybe someone could help.

I only have this bad foto of the rotors: the left one is for the very first red pickup. The right one for the second generacion of red pickup as well as for the black pickup:

k-IM000833.JPG (28 KiB) Viewed 12586 times

[72degrees]

The rotor of the pickup looks like the very first one.
There are two kind of red pickups! Maybe that you have the second generation of red pickup in combination with the first generation rotor? The difernce can be seen if you compare the length of the visible metalic parts (don´t have the right word ) inside the pickup. Right now I don´t remember the right measure of each, but maybe someone could help.

From the Dutch Morini club web site:
"The first (older) red pick-up.: The older version has a magnet with a grey colour and it looks like it has been milled. Also the name "Ducati-Elettrotecnica" has been written on it in very small letters. The matching pick-up can be recognised by the soft metal parts of the coils inside. The soft-metal strips inside have a width of ±13 mm.
◦The second red pick-up.: (used until ±1981) has a copper/golden colour magnet, which looks like it is made from a pressed piece of metal. It has no writing on it. The soft-metal strips inside are ±7 mm wide. In case you would swap the magnets of these red pick-ups, you will interfere the ignition timing badly. Both these red pick-ups should be used with the black transducers (square boxes) only."

Difficult to tell from the photo but the strips on this look fairly wide - so probably an early pickup that matches the rotor.

[Long_Road]

Thanks for the information! No eureka moment for me yet unfortunately, but some more photos may be informative:

DPP_0008.JPG (210.81 KiB) Viewed 12580 times

DPP_0009.JPG (196.4 KiB) Viewed 12580 times

DPP_0010.JPG (198.7 KiB) Viewed 12580 times

Couldn't see any coloured dots on the transducers, but then I don't know where they are.