Laverda 3CL - help needed

Andy B

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I know there are some Laverda enthusiats on here so I wondered if I could run a quandry past you!

I've been helping my mate rebuild his 3CL and we are done except for ........

It won't tick over properly. There are 2 symptoms that may or may not be connected.

The first is with the choke. When the engine is warm the only way to get the bike to tick over at sensible revs is to leave the choke about a quarter open. If you close it the bike just revs at about 5,000 rpm. Likewise, if you go to full choke it revs.

The other symptom is that with plenty of fuel in the tank (full) and the taps set to open the bike will eventually die from fuel starvation. If I switch it over to reserve it is fine. There is one other test I want to do tomorrow when I can ride the bike again - try one tap on open and the other on reserve and see if I can identify whether it is just one tap that is the cause.

Col and I are really scratching our heads on this one. Can the huge reserve of experience on here offer any ideas on the cause of our problem(s)?
 
Fuel flows on reserve but not when the tap is set to the normal 'on' position? Stripping and cleaning the tap/s would appear to be the solution? It may be that the fuel tank cap vent cannot supply enough air to cope with two taps so clean that out too?
 
The fuel tap problem is almost certainly because of crud in the pipes that stand up into the tank or there may be small filters that sit behind the moving part of the tap though that depends on the taps fitted because there are several different types that Laverda used over the years and from my limited experience they're mainly interchangeable.

The choke issue might be caused by the O ring on the choke plunger being worn out but if it's got pumper type carbs they're horrible things that are full of tiny little galleries that clog up over the years and need cleaning properly in an ultrasonic tank with the right cleaning agent in there.

This might help
https://www.ducatimeccanica.com/dellorto_guide/dellorto.html
 
Thanks guys. I am going to start with the taps. One looks original and the other a replacement. Until I get them out I'm not entirely sure what I am dealing with but I am told there is a gauze filter over the top of the two pipes. That's not to say something hasn't got through.

The carbs have been stripped, gone through an ultrasonic bath and rebuilt with all new parts. Colin did this. I am wondering whether there is a way to put the choke back together incorrectly so another stripdown awaits! Going to start with the taps though.
 
bit late now and you are probably sorted.

the guys at SPR Racing at Ruddington are ex laverda racers and still look after Laverdas for local riders. Well worth getting in contact with them if you need any tuning or service work doing http://www.sprracing.co.uk/dyno great prices as well.
 
I had this problem on 70s bikes. The normal fuel tap position (via the stand pipe) gets clogged so the bike will only run on reserve. That's less dirty d/t less use.

High revving on choke can be the fast tickover has been set too fast. It can also happen d/t fuel starvation (see above). Too little fuel = revs but no power.
 


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