New carburettors or clean/update

Paul Marx said:
Forget all that crap about carbs and ignition, your plugs are just too warm.
Paul

Thank you, Paul!
Lean carb and wrong plug might be a bad mix.
I found used NGK B8 and B9s in my garage.

Green book says Champion N2 and Bosch W260T2. My original manual complete with oily thumbprints tells me how to dismantle the engine, only says the oil should be Shell MO 100 and nothing about spark plugs  :)
Laverda twins and triples bible says Lodge RL 49..

I think I must have got the spark plug type from the Laverda spares dealer I used.
 

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On a Laverda twin, each set of points opens once every 2 rotations on a points cam that runs at half revs. Most racing car engines before electronics became common ran reliably on one set of points opened by a 4 lobe points cam and at far higher rpm than most of us will use on our SF today. This was pointed out to me by a top race car tuner here when we discussed exactly the issue in this thread.
Yes, electronic ignition save you some uncertainty, and as long as it doesn?t give problems and ditch you at the roadside, is a no brainer "set and forget". Laverda would have done well to run the 3C on points (as would many other manufacturers)  for a few years before going electronic when it had proved itself reliable. It was the number one fault with triples when I worked for Stanco (Oz Lav importers). Or do a thread search here for people fault finding their electronic ignitions.
No, points are not the achilles heel of everything they were ever mounted on.
For myself I find it enjoyable to check the timing once a season (and find it very close to spec), and to buff the points and set them every year or so, a drop of oil on the points cam etc, easy peasy. My road SF, with my ex-race 10.5 pistons required "re-mapping" so I simply modified the advance unit and I have it 5deg btdc at start and max advance 29deg btdc at my chosen rate. Also easy peasy. I certainly don?t ride around terrified that my timing is out and the engine about to self destruct. SFCs won all their titles with points fitted.
My bike also has Dells on it, they really should be junked and I should fit multi-map fuel injection.
If people want to go electronic, let them, but don?t go around telling people that they are risking their engine.
There, got that off my chest  :)
 
Laverdalothar said:
I have done Ultrasonic cleaning of several carb sets, mostly PHF though. I did not have a blocked passage, but just dirty carbs. On these, it worked well with the right solvent.

Regarding Points: from what I have heard, you won't recognise in most cases the fault until its to late. Hard to hear pinging when you ride with a helmet on at 4.000Rpm and with these exhausts... And the real trap is, that they might stick at full advance only to go back to standard when the bike cools down (after the piston has been holed...), which makes it almost impossible to find the fault.

Any bike I had from Laverda, I have modified to DMC (1 or 2) if it wasn't already. The new project will receive an ignitech solution and my SF (0) also got one when i rebuilt it. Idled like a Diesel truck and no worries about anything anymore in that area...   ;)
Thank you Laverdalothar!
I think I will try ultrasonic cleaning. Changing jets, etc. and hopefully correct spark plugs.
I have had problems with the advance unit on another bike, but then the bike was not running well.
With my SF I heard the pinging allright.  If I had stopped it would have been OK. However I was 2000 km from hom and was just being passed by another SF 750, so I opened the throttle  ;) Rest is history.
 
Ernesto said:
Hello,
Stein-Dinse lists the V3 needles again marked as in stock.
PHF carbs can be used, the accelerator pumps can be deactivated
in a couple of minutes.
I still use points without problems since 80k.
But be sure to check your ignition as a possible cause before you reuse your bike,
like Lothar proposed also the free running of the advance mechanism.
And the isolation plates and their o-rings between inlet stub and head.
Sometimes, when they're very old, the black plates tend to crack. Have seen
some piston damages because of that. No holes, but seizures.

hth
Ernesto
Thank you, Ernesto!
I will check the ignition and the advance unit, had trouble with that on another bike.
The isolating plates seems a little squashed, so might be a good idea to change.
 
Tippie said:
On a Laverda twin, each set of points opens once every 2 rotations on a points cam that runs at half revs. Most racing car engines before electronics became common ran reliably on one set of points opened by a 4 lobe points cam and at far higher rpm than most of us will use on our SF today. This was pointed out to me by a top race car tuner here when we discussed exactly the issue in this thread.
Yes, electronic ignition save you some uncertainty, and as long as it doesn?t give problems and ditch you at the roadside, is a no brainer "set and forget". Laverda would have done well to run the 3C on points (as would many other manufacturers)  for a few years before going electronic when it had proved itself reliable. It was the number one fault with triples when I worked for Stanco (Oz Lav importers). Or do a thread search here for people fault finding their electronic ignitions.
No, points are not the achilles heel of everything they were ever mounted on.
For myself I find it enjoyable to check the timing once a season (and find it very close to spec), and to buff the points and set them every year or so, a drop of oil on the points cam etc, easy peasy. My road SF, with my ex-race 10.5 pistons required "re-mapping" so I simply modified the advance unit and I have it 5deg btdc at start and max advance 29deg btdc at my chosen rate. Also easy peasy. I certainly don?t ride around terrified that my timing is out and the engine about to self destruct. SFCs won all their titles with points fitted.
My bike also has Dells on it, they really should be junked and I should fit multi-map fuel injection.
If people want to go electronic, let them, but don?t go around telling people that they are risking their engine.
There, got that off my chest  :)

I think you are onto something, Lee!  ;)
Seriously - it should be possible to run with points, and thank you for contributing!
 
I found used NGK B8 and B9s in my garage.
At least the "8"s shouldn't be problematic, don't worry about that.
Otherwise the usual suspects like OCT or Wagner wouldn't sell them.
But for the "small engines" up to 72 the BP 8 ES is recommended (also
in the NGK list). The "p" means "protruding electrode".
You won't find the Bosch 260s, they've changed the denomination system
more than once since that time.
Concerning Champions I,ve seen bikes run very well with them, others (like
mine) don't. And they're hard to find "round the corner".

Ernesto
 
Thanks for giving the right recommandation! I have a new set of B8EV, which I guess should be OK then.
I know W7DC is possibly a newer version of the W260T2, my point was that it is a little bit funny that the manual shows almost how to dismantle the engine, but doesn't tell which spark plug to use  ;)
Nothing wrong with other makes than NGK, but the shops I have visited seems mostly to carry NGK.
 
Tippie said:
SFCs won all their titles with points fitted.

Well - they also won on tires you would be scarred to death riding today after having ridden BT45's... ;)

I agree that most of my experience results from triples, and their system is not the best, really... with the "Bosch" engines, moving to an electronic system like the DMC or REDAX Sachse system does offer way more than just an "install and forget" system. It offers better (DMC) or REAL (REDAX) charging power. by reducing the electric consumption of the ignition system and a second charging coil (or a complete new system in case of Red's system).

for the Twins, it only offers peace of mind regarding the service of the unit. However, ask Piet how many engines he has had on his bench that suffered from a locked advance mechanism. For sure it is not EVERY engine and it absolutely has to do with the quality and sequence of service the bike gets. However, it CAN be an issue if you don't service it regularly. As I had very good experience with the DMC on my triples, it was one of the first things on the shopping list for the 750SF, too. And if I read the last comment of the starter of this thread regarding the situation the initial fault happened, it could well be a sticky advance system was the cause...

but - what ever: either service the points correctly or bin them for an electronic system: it will be a very nice bike still, as it is a Laverda Twin - on of the best sounding bikes I have ever had!

 
Paul Marx said:
Small valve high compression 750s, S or SF need care in setting up ignition and carbs and need COLD plugs as in B9.
Paul

phil37 said:
Always used 9 on the road or 10's (for racing) - have seen a few pop pistons with B8's - Regards - Phil

Thanks, Paul and Phil!

I might very well have used 8s. The only thing I know is that I found both used B8s and B9s in my garage.
 
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