Start-up problems Laverda 650 Sport (1994)

L

liebig

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Sweden
A mate of mine has bought the above model recently (I bought my Alpino at the same time from the same guy) and experiences a strange start-up problem.

It's seems the old girl wets herself extremely easily causing the spark plugs to fail (when the plugs are pulled they are indeed very wet). She can start one moment, then for a number of next attempts she just refuses and may need an overnight rest until new attempts may again be fruitful.

Now, my mate is no slouch with Italian primadonnas, but is scratching his head on this one.

Battery's been changed to a brand new one. Spark plugs, changed. Wires checked. He's got several chips (for the ECU) to chose from with the bike, and non seem to work better than the other. Injector cleaner added to the petrol. Choke on and off.

The starter is a bit loud, definitely louder than on the Ducatis and also the Alpino (oooh, the Alipnos' a sweet starter  :D), but seller claims this is how it should sound.

Anyone been there, seen that and solved the problem?
 
Check what the battery volts drop to when winding it over, maybe the noisy starter is pulling too much current. Easy and quick thing to check before getting too involved.
 
Had the bike been sitting for a long time before it was purchased? Fuel pump shouldn't cause wet plugs but the rubber fuel hose in the tank can break down very badly with age and lack of use.
 
Yeah. He's thought about that hose too, but then there should rather be not enough fuel than too much (wetting the plugs), no?
 
I had to replace all the fuel lines, fuel filter and clean the fuel gauze at the bottom of the tank on a 750S.
Bit of a serious job to get the tank off, dismantled half the bike, no kidding.

Rear wheel, inner mudguard, battery, tank cover, airbox and injectors, remove rear subframe after undoing all the electrical connections.
Then fish out the fuel filter and pump that live inside the tank.
Then wrestle the bastard fuel tank out.
Wrestling it back in was even more of a bastard job.

Reason for replacement was that all the hoses had perished and fuel was leaking everywhere once the hoses were pressurised.
The bike would still start but leaking fuel under the injectors was no laughing matter.

So the wet plug problem may have it's root cause elsewhere.
Look everywhere else before replacing fuel hoses.
Trust me.
 
I had a really similar issue to that on my 95 Ducati 750ss. I did all the things Grant did above , but wasn?t so painful as the 750 sos is more simple to pull apart. The fuel hose in my tank had gone like liquid goop and got into the carbs, which was Intermittently stopping the floats from closing and flooding the engine . I?m not sure if the Laverda set up is the same, but the fuel hose that was buggered was the bit after the in tank filter and on to the fuel pipe spigot on the interior of the tank.  So it missed the feudal filter completely . So sometimes the bike would start and sometimes it would flood.  Just a thought anyway to check inside the tank. 
 
Many, many thanks lads for all the input. I'll make sure to pass it on and also fill in with the progress.

I understand that to get the battery out you have to take out the rear wheel. Only in Italy...  :D
 
Just to add to what has been said above, if your fuel lines in the tank have not been changed they should be changed now.  They only last c. 20 years it seems.  The fuel filter is a 5000km service item in the owners manual, so worth getting in there anyway.

Speaking of the owners manual- probably worth a read.  On page 83 it shows you how to take the battery out - without removing the rear wheel 😀

The starters aren?t noisy.  If it?s clattering then you need to change the starter clutch.  In this video you can hear what the starter should sound like. https://youtu.be/YUMtfYIuuJM

Good luck,
Ian
 
Obviously, fuel gets into the engine.  Does it spark?

If the engine spins over quickly on the button, check compression.  Typically, the starter only just manages to turn the engine, often a very hit-or-miss affair, but will start eventually.

Try push starting.  With low compression, it just needs more revs to fire up.  Doesn't distract from the fact it would be quite knackered though...

piet
 
sfcpiet said:
Obviously, fuel gets into the engine.  Does it spark?

If the engine spins over quickly on the button, check compression.  Typically, the starter only just manages to turn the engine, often a very hit-or-miss affair, but will start eventually.

Try push starting.  With low compression, it just needs more revs to fire up.  Doesn't distract from the fact it would be quite knackered though...

piet
Click to expand...

No mention of putting a match to it Piet! You must be mellowing..... :D :-*
 
Whilst Piet is absolutely right to suggest a compression check, in my experience even with full compression the 668 motors crank over fine if your starter is healthy.  The same cannot be said for the 750s however.
 
Grant said:
Bit of a serious job to get the tank off, dismantled half the bike, no kidding.

Rear wheel, inner mudguard, battery, tank cover, airbox and injectors, remove rear subframe after undoing all the electrical connections.
Then fish out the fuel filter and pump that live inside the tank.
Then wrestle the bastard fuel tank out.
Wrestling it back in was even more of a bastard job.

Trust me.
Click to expand...

I'm hearing you, Grant. I've done two ... and it doesn't get any easier - even removing the CPU wiring is a friggin pain in the arse big-time. I call it bad design, absolutely no justification. Love to ride one, would despise owning one.
 
Grant said:
I had to replace all the fuel lines, fuel filter and clean the fuel gauze at the bottom of the tank on a 750S.
Bit of a serious job to get the tank off, dismantled half the bike, no kidding.

Rear wheel, inner mudguard, battery, tank cover, airbox and injectors, remove rear subframe after undoing all the electrical connections.
Then fish out the fuel filter and pump that live inside the tank.
Then wrestle the bastard fuel tank out.
Wrestling it back in was even more of a bastard job.
Click to expand...

It's strange isn't it? My Zanes must be built differently to everyone else's.

I take the throttle bodies/air box assembly off and remove the access plate, then remove the back wheel and inner guard and take the fuel pump base out. expect a bit of fuel to fall out here. This then allows me to pull new hose through, with a non generic smaller diameter filter Ryco Z200 through. There is a hole in the internal framework that the oem filter wont fit through. Fit the new pump to the base, connect the hose, and then fit it back in. It's a few years since ive done it, but I don't remember any major issues, just a bit fidly getting the bottom base plate screws out
 
I'd be having a good look at the adjustment of the throttle position sensor.....and checking that it is actually working.....use GuzziDiag?.
 
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