Hi, my 1979 Laverda 1000 3CL runs nice and smooth until it stalls and stops every 20 to 50 Km. When it rests for a while, it starts up fine and runs nice and smooth again for another 20 to 50 Km. It seems like gasoline starvation, but the gas hoses have gasoline. Gas tank was professionally repaired (interior coating) and fuel taps are new. I am running on the original Bosch ignition and coils. I am not sure if the original Bosch ignition and coils could be the issue. Any suggestions are welcome. Thank you!
Laverda 1000 3CL Stalling
- Thread starter Mage
- Start date
chris78jota
Senior member
- Location
- England
I was just typing exactly the same as Phil 
You won't do 5km if the tank isn't venting.
Change the coils. They work fine when cold and don't work when hot.
Paul
Dellortoman
Hero member
- Location
- Tasmania, Australia
I think Paul is on the right track with ignition rather than a fuel feed problem. But heat failures aren't limited to the coils. It could also be the BTZ boxes or the pickups. They can fail when they get warm but work again when they cool down, as can pretty much any electrical component.
The bike has 2 independent ignition systems, one for the outer pair of cylinders and one for the centre cylinder. It seems unlikely that both coils, or both BTZ boxes would fail simultaneously. So, is it cutting out on all cylinders, 2 cylinders or just one? Figuring that out will give you a clue where to look for the fault.
If it's cutting out on all cylinders, then it's likely to be an electrical problem that's common to both ignition systems. That pretty much limits it to the power supply and/or earth connections for the ignition system. A corroded electrical contact (possibly a fuse) can sometimes fail in the way you describe. If it's making poor contact it'll get hot and can break contact, but then work again when it cools down.
If not all cylinders are cutting out at the same time, then it's likely to be one of the ignition systems that's failing. Un-plug the Bosch BTZ boxes and swap them over. If the fault transfers to the other cylinder(s) then you've found the problem. If not, then it might be coils or pickups. The coils aren't interchangeable, and it's not so easy to swap pickups, but there are other ways to check their health. We can get into that if necessary when you've narrowed down the possibilities.
If it was my bike, I'd junk the original ignition system entirely and install something modern. That old Bosch system with its lousy advance map is well past its prime (it was never much good even when new). A modern ignition with a sensible advance curve will make a big improvement to how the engine runs. My recommendation would be the Redax/Ignitech system that also comes with an alternator upgrade.
The bike has 2 independent ignition systems, one for the outer pair of cylinders and one for the centre cylinder. It seems unlikely that both coils, or both BTZ boxes would fail simultaneously. So, is it cutting out on all cylinders, 2 cylinders or just one? Figuring that out will give you a clue where to look for the fault.
If it's cutting out on all cylinders, then it's likely to be an electrical problem that's common to both ignition systems. That pretty much limits it to the power supply and/or earth connections for the ignition system. A corroded electrical contact (possibly a fuse) can sometimes fail in the way you describe. If it's making poor contact it'll get hot and can break contact, but then work again when it cools down.
If not all cylinders are cutting out at the same time, then it's likely to be one of the ignition systems that's failing. Un-plug the Bosch BTZ boxes and swap them over. If the fault transfers to the other cylinder(s) then you've found the problem. If not, then it might be coils or pickups. The coils aren't interchangeable, and it's not so easy to swap pickups, but there are other ways to check their health. We can get into that if necessary when you've narrowed down the possibilities.
If it was my bike, I'd junk the original ignition system entirely and install something modern. That old Bosch system with its lousy advance map is well past its prime (it was never much good even when new). A modern ignition with a sensible advance curve will make a big improvement to how the engine runs. My recommendation would be the Redax/Ignitech system that also comes with an alternator upgrade.
Andy
Hero member
- Location
- Auckland, roughly
I agree.
It’s either fuel or electrical.
It’s either fuel or electrical.
Tree Hugger
Full member
- Location
- Scotland
I once had a battery earth that vibrated loose and provided intermittent connection. At rest it reconnected and the bike started.
+1 for Cams post, when you say "stalls" a better description of the off normal engine running ie when the actual problem or problem symptoms occur. Also you mention a "tank" rectification, did this issue happen pre and or post tank rectification, chemical coating. When you attempt a quick restart, is there any sign of engine firing or complete no ignition of cylinder load. Description overall is good, need more details, including what Cam has indicated. Shotgunning the ignition system can shorten the diagnosis though some times, narrowing down to fuel or ignition can bring a more certain outcome. Caveat, nothing to be gained by crippling a lovely motor with the oem Bosch BTZ, unleash that motor and matching overcompensated carby settings ie 65 pilot jet is ludicrous, that size to stop the gross pinking at low rpm on a one step BTZ, HTH j
helicopterjim
Hero member
- Location
- near Lone Butte, BC, Canada
Hi all, Thank you very much for all your replies. The bike is at the mechanic. It also stalls with the gas tank cap open. The symptoms are: starts perfect, runs smooth and engine stalls but doesn’t stutter – it stalls gradually over several kilometres until it dies. The problem occurred before and after the tank coating. When attempting to quick start, the engine tries to fire up. Carbs have been tuned. I think Paul and Dellortoman may be on the right track. I haven’t checked if it is cutting on one or two cylinders yet. I purchased some used BTZ boxes off eBay, so I will give that a try first, then coils.
chrisk
Hero member
- Location
- Brisbane, Australia
Ok on further symptoms, BTW not all BTZ units are the same in characteristics, not a universal module, as useless as they are, ditto the anti start resistors, HTH j
Huh so when I bought my very first bike which was a green 3CL when we went to look at the bike it wouldn’t idle, I remember the seller saying its an Italian racing bike its not meant to idle.. to which my good buddy Ric ( who is on here ) quipped back with oh you dont know Brett he will get it to idle…. Correct on that part about an hour or so into ownership and she was idling .. I loved that bike and perhaps in the bowls of the garage after 40 odd years it may well be back to where it once lived. Another story for another time.
Often the very most over looked and incorrectly set of all the tuning nightmares that are created by the great unwashed on a Laverda. Now time and time again try to explain how it’s done but does anyone listen, perhaps you need to understand how a carburettor works right, I mean am relatively a newbie to the world of ICE engines and carb a rooster. There again what would I know right.
Oh and just very quietly and on the down Lo, have been playing around with and driving a non ICE powered vehicle for the last couple of days and hmmm don’t tell anyone but well all I will say is simply amazing
and such a way different experience its like a window into someone‘s future but not mine… even more instant throttle response than a 6.2 supercharged Hemi that also drove earlier in the week. …. Just mind boggling and whisper smooth and quiet when compared to the TRX
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chrisk
Hero member
- Location
- Brisbane, Australia
A couple of weeks ago in Adelaide, a bloke on a sizeable motorbike pulled in front of me at a set of traffic lights. On green, it launched, and I mean launched like a top fuel drag bike ….. not a sound to be heard. What is this fucken world coming to?
rocketonarail
Hero member
- Location
- Gloucestershire,England
Seems more and more of these bikes are " currently " becoming available.....did you " charge " after it or " resist " the temptation ...I`m a little con- "fused "over this .....