Laverda 750 sf2 doesn't start

W

Wido Veldkamp

New member
Location
Netherlands
Hi Guys,

I need some help. I'm currently working on a laverda 750sf2 (1974) which i inherited from my old man. It has been standing still for a couple years now, but before that it was running fine. It already had an electronic ignition modification. I've made a new exhaust system for it because the old one was dead. And renewed all the old wiring.

Problem is that it refuses to start. It looks like a fuel problem. The sparksplug are firing fine. Carbs were ultrasonic cleaned and are super clean. The fuel reaches the floating chambers, but it seems to stay there... doesn't reach the expansion chambers. The sparkplugs stay completely dry ....

Any ideas where to look for this problem?
Tnx in advance
 

Attachments

  • 20221128_165627.jpg
    20221128_165627.jpg
    166.6 KB · Views: 42
ignition timing adjusted? Compression is fine? Valve timing ist ok? Change the spark plugs. Try starter spray?
 
What ignition? If two coils, are they on the correct side?
With full choke and closed throttle you would expect the plugs to get wet. If an inlet air leak it won't suck fuel in.
 
Tippie said:
What ignition? If two coils, are they on the correct side?
With full choke and closed throttle you would expect the plugs to get wet. If an inlet air leak it won't suck fuel in.
Click to expand...
This seems to be the problem, it doesnt suck in the fuel....
I'll have a look tommorrow at the ignition. But this worked fine before. I really think its a fuel problem
 
Petrol goes from tank, to float bowl, through jets if float level is correct and to combustion chamber where a spark ignites the mixture at the right moment.
Check all.
They are extremely simple contraptions so the problem is simple to solve.

Paul
 
Exmoor beast said:
it should suck your hand onto the carb- if it’s blowing - valve timing (bent or stuck open valve - my Montjuic ate a 6mm nyloc nut! ) blocked exhaust, engine turning backwards(??) Did you do the valve clearances?
Click to expand...
No didn't check them yet. But i it ran fine before we put it in the garage...you can't get a bent valve from just standing in de garage. But i'll have a look af the valve timing. Tnx
 
Wido Veldkamp said:
No didn't check them yet. But i it ran fine before we put it in the garage...you can't get a bent valve from just standing in de garage. But i'll have a look af the valve timing. Tnx
Click to expand...
You can if it’s got open carbs and somethings gone down, first time you start it.
My Monty ran for A few seconds , then just spun over on the starter not even coughing.
Best of luck, hope it’s not serious.
 
ljen said:
As said; valve timing/ clearance? Old fuel often is a problem.
Click to expand...
Old fuel may be the problem.
Today it is not a problem with my Laverdas but I omce had a Bold‘or. After 4 weeks in the garage it did not start with the fuel in the carbs. I always had to drain the carbs and then with fresh fuel from the tank it started…..

If the bike was standing for years the fuel may have lost the ingredients, which ignite the fuel easily.
 
andre g said:
Old fuel may be the problem.
Today it is not a problem with my Laverdas but I omce had a Bold‘or. After 4 weeks in the garage it did not start with the fuel in the carbs. I always had to drain the carbs and then with fresh fuel from the tank it started…..

If the bike was standing for years the fuel may have lost the ingredients, which ignite the fuel easily.
Click to expand...
I will defenitily try that...but even with old fuel the spark plugs should become wet right?
 
You must log in or register to reply here.
Back
Top