Weak Starter Laverda SF [1972]

T

tobiask

New member
Dear Laverda enthausiasts!

Last week I decided to try and start up a Laverda SF from 1972 which hasen't been ridden for at least 10 years. The bike was stalled in working condition in a warm and dry place.
I bought a brand new battery and charged it before trying to start the bike, this is what I got:
Laverda Start attempt

I looked through all the forums and checked both the electrics leading up to the starter as away from the starter. Applying the voltage directly to the starter terminal (by-passing the solenoid etc.) gives exactly the same weak performance of the starter.

I opened up the starter motor and found the carbon brushes to be in good condition and while I was there I cleaned the lot with contact cleaner.

Still the same poor result. The starter does turn but does not have the power to turn through compression. After several attempts it will 'stumble' through compression but I don't think this is what a start up should sound like!

Merry christmas and I hope to hear from you!
Tobias
 
Yeah, Tobias, at least turn it over a few times with the plugs out and try to get some 10 year old "lubricating" oil up to the top end and onto the cylinder walls before you try to fire it up.
And you didn't say but I'm assuming you're using fresh fuel and have drained the goo out of the carburetors?

Ken
 
tobiask said:
I opened up the starter motor and found the carbon brushes to be in good condition and while I was there I cleaned the lot with contact cleaner.  Still the same poor result. The starter does turn but does not have the power to turn through compression.
Click to expand...
As the others, Tobias; but here's another angle, in case it helps:

Did you spin the starter motor up while it was on the bench?* 'Cos what we don't know is if it's a weak starter motor.  Or a healthy starter, trying to turn a stuck engine ...

Ciao

Craig

* Should go like a crazy, crazy thing.  So make sure you've got it VERY FIRMLY clamped in a vice before attempting this at home, kids ....
 
Thanks for the many posts! Clear overview answering the questions
-Removed spark plugs, engines runs freely (I dripped a little oil in the cylinders)
Laverda Start attempt NoSparkPlugs
-Drained the carbs to prevent gum from entering the system
-Contacts seem in good condition
-Took out starter motor and it does spin like crazy in the bench!

Actions:
-I tried to start while by-passing both the + trail and the - trail (So hooking up the red cable directly to starter, and hooking up black cable directly to battery, avoiding the earth system)

I am starting to think the starter is the problem, although it clearly turns. What should be the amperage through the starter motor while in the bench?
Or should this only be measured while installed? Is the motor turning around as quick as expected in the video (Laverda Start attempt NoSparkPlugs) where the plugs are removed?

Thanks guys!
 
Tobias,

The starter will draw anything between 50 and 250Amps, depending on the condition of the starter, resistance (or lack of) due to engine condition, compression etc, and if your battery is up to it.  Expect to see around 80-120Amps for a second or 2 before the engine fires.

There's a planetary drive inside the alloy housing of the starter to reduce the drive ratio to the crank.  Might find that jamming due to extreme wear once loaded.  They're usually brim-full with grease, but you never know what the DPO has been up to!

Your no plugs start-up sounds quite normal to me.

The ND starters are extremely rugged and normally very reliable.  Quite rare to have one give up.

piet
 
Ex ILOC chairman Pete Brendon got his GTL starter rewound because it wouldn't turn the engine over properly and was drawing high current. Once reconditioned it worked very well. If you told us where you are, you may find someone nearby who can let you try their starter on your bike to help diagnose where the problem is. :)
 
I have a Honda CB550 that I got in pieces and assembled. The main battery cables looked fine with only a tiny bit of corrosion at the battery ends. Cleaned them off and installed during the course of the rebuild. Found on trying to use the electric foot that it cranked slowly,tried another battery,figured it was just a limp starter. Riding the bike later it just cut off. After retrieving it I started to trouble shoot and everything looked fine,nothing loose or burnt,fuses good,switches good and so on. In the scratching of my head and other parts I bumped the neg. cable and suddenly there was the ign. light! The outside of the cable looked fine but stripping the insulation back revealed that lovely blue/green powdery crust surrounding a very thin crispy black few strands of copper that used to be the conductor. Checked the pos. and the same thing.
I'd suggest you try at least some jumper cables directly on the starter and see what happens.
 
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