First impressions

michipons

michipons

Hero member
Location
Palma de Mallorca
Hi!!

Today big day for me, first day riding my restored Laverda, and my first Laverda ride ever!

Bike started perfectly, just did a few "hear" adjustments in the carbs, so I did around 100k. Overall was great! great feeling.

Some minor came up: a drop of oil out of the rpm gearing, primary chain needed a bit more tension, and some light issues. At the end of the drive, when adrenaline went down, I realise that the bike vibrates considerably, but not to the point of getting uncomfortable. I have to check more carefully the ignition timing and the carburation, this will be an interesting topic because I have realised that the advance system doesn't work properly, as with the static method is adjusted to the mm and with the engine running the marc on the flywheel is to the left, so i am already considering to install an electronic system :LOL: :LOL: (some people will say, I told you, others.. don't do it!!) But the fact is that the engine run very smoothly! But I will leave that for another topic...

Now, I am very confused with the blue beam light. As I understand, the blue beam light indicates the high beam light is on (long lights), beeing the middle switch position the short ones and the upper spring loaded and the lower position the high beam (long) lights. Well, my blue light goes on exactly the other way around. But, according to the wiring diagram it should be this way!! So is the diagram wrong or I am thinking wrong because I am comparing the blue light with the car instruments?

In the diagram the blue cable out of the blue indicator goes to number 20, from there it goes to the middle position of the switch and via the 10 to the bulb 56a... which is the low beam...
:-\

Miguel

https://youtu.be/pA5sQt682cY
 

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Congratulations on your first Laverda ride. I've never ridden a Laverda 750 SF(x) so dunno how much they should vibrate, but if it's anything like an old Triumph 360? twin, then it might shake your teeth out if you rev it enough.  :D

If it's the same as the triples, then the blue light should come on with high beam. Just switch the feed wire over to the high beam circuit, regardless of what the wiring diagram says. I don't have a wiring diagram in front of me so don't know if it's right or wrong, although it's certainly possible that there's a mistake in the diagram. There's an error in the factory's 3C wiring diagram.
 
I remember from that time that some other Italian bikes had the light for low beam only. I am pretty sure that Laverda had it just for high beam though. Very easy to change, just mate it in to the high beam circuit instead if you want to.
Vibration will be noticeable but generally smoothes out considerably all the way through the mid range - depending on many factors. Any good one is very smooth until about 150km/h, I have found, and never get really bad (nothing like any Triumph I have ridden) even up to redline but I can't ride like that any more or I will go to jail in this country.
 
Congratulation on your first ride Miguel. The 750 twin is different, but it grows on you very quickly ;) Valve adjustment, ignition timing and carb sync make a world of difference. Some engines have better balanced cranks.

Keep an eye on all fasteners as they tend to shake off over time.

Keep up the good work
Gerald
 
Hi!

I have attached in the first message the wiring diagram... in case somebody wants to check it, funny thing is that in two different diagrams I have, the blue light is connected to the low beam circuit!

Maurice! :LOL: :LOL: that's the plan!

Gerald, thank you for the advices. The crank was balanced from Keith, so I expect it to be not the issue. I don't want to get crazy with this vibration, still will make some checks, it only becomes unpleasant when maintaining 120/140 kph constant on the highway, normal curve driving is not a problem.

Now I am fixing the electric issues, then I will syncronize carbs and ignition timing and lets see if there is any improvement.

Miguel
 
I fitted a Wassell Vape electronic ignition (for Triumph/BSA) on my SF3 using an adapter plate from Phil Todd and it has transformed the bike, starts on the button, picks up quicker and runs smoother. I set max advance at 34?. Best thing is I don't have to set the points every so often. Main reason I fit it was a couple of the threads had gone on the points back plate. I balance the carbs with a home made vacuum gauge.
 
Hi, Miguel.
If the mark in the flywheel is out to the left, Ignition is too far advancred, which is dangerous.
Btw, did you check for the correct position of the mark on the case (tdc)? Sometimes they are
Out of line.
I recommend not revving her up more than 4200rpm before retightening the head.

Cheers, Ernesto
 
Hi Ernesto,
No i didn?t check it, but good point, I will do it. the thing is that when checking it with the bulb methode, is right on the spot (with the case line), and with engine running, i a bit advance (at low idle). So according to green book, that is a symptom of worn springs in the advance system, which is realistic. So I guess before plying around with it, I will install electronic ignition...
BUT engine is running super smooth and starts with first crank turn!!

Ernesto, to re-tighten the head, is possible with engine on the frame?

Regards,
Miguel
 
Too much advance would indicate weak springs.
I'm looking for a source of new ones.

You can torque the head with engine in situ, you need a crows foot end on the torque wrench but....
It's always seemed silly to me to want to torque a head that suspends the engine without "un"suspending it.
So easy to tilt the engine forwards when exhaust and carbs are off and secondary chain slack..
A few hours work and a properly torqued head.

Paul
 
Ernesto, to re-tighten the head, is possible with engine on the frame?
Click to expand...
Only partly.
Like Paul already mentioned, it's no big deal to tilt the engine front down. Support the front with a wooden block.
Losen the lower bolts and remove all other bolts.
You have to remove the exhaust parts, the revcounter cable, tilt the horns forward and check, if the electrical
cables have enough play. Open the secondary chain.
Different to Paul I always left the carbs and the clutch cable in place.

Nevertheless I find it peculiar, that it reaches too much advance. The advance unit has a mechanical limit,
that is reached before the springs are fully expanded. Maybe one of the REAL experts has an idea.

hth,
Ernesto
 
Paul Marx said:
Too much advance would indicate weak springs.
I'm looking for a source of new ones.

You can torque the head with engine in situ, you need a crows foot end on the torque wrench but....
It's always seemed silly to me to want to torque a head that suspends the engine without "un"suspending it.
So easy to tilt the engine forwards when exhaust and carbs are off and secondary chain slack..
A few hours work and a properly torqued head.

Paul
Click to expand...

Hey Paul!

Tilt the engine looks best solution, however it looks like a big job.. all exhaust system out, loose all engine mounting bolts, carbs.. and probably many more things🥴. what about a lifting table under the engine just pushing up enough to release the weight of the engine from the head bolts??

Would be great if you can source those springs!

What is the best electronic ignition price/quality and easy installation for the 750? And easy to get in EU?

Miguel
 
It's quite easy to tilt the engine Miguel particularly if it's all newly built and clean. You just need to leave the lower rear engine bolts in. I use a car jack under the engine to lower it and lift it back in position.
An easy days work if you aren't distracted.

As for the springs, I'll see if I can get a quote to have a series made but I'm not certain many people would be interested.

I know nothing about electronic ignitions for 750s.

Paul
 
Electronic Sachse is pretty much plug and play. You can use your two original coils or fit a twin pole coil, as the system uses wasted spark principle. Ignitech needs some setting up knowledge. I think Redax has a system ready to fit to SF.
It is your choice to chuck the points but the advance system is extremely simple. If you remove the unit you can see that advance range is regulated by a pin in a hole, so it should not move more than 20 degrees at the unit (40 at the crank). The rate of advance up to 40 degrees at the crank can be altered by simply rotating the spring holding plate.
I have altered these units to both run with an electronic trigger, which due to the lack of drag against the advance unit required making the springs more effective by rotating the plate, and I have also reduced advance range for use with points by adding a dab of weld to the resting side of the hole to give max 30 deg crank advance for higher compression motors. Very easy to play with.
 
Tippie said:
Electronic Sachse is pretty much plug and play. You can use your two original coils or fit a twin pole coil, as the system uses wasted spark principle. Ignitech needs some setting up knowledge. I think Redax has a system ready to fit to SF.
It is your choice to chuck the points but the advance system is extremely simple. If you remove the unit you can see that advance range is regulated by a pin in a hole, so it should not move more than 20 degrees at the unit (40 at the crank). The rate of advance up to 40 degrees at the crank can be altered by simply rotating the spring holding plate.
I have altered these units to both run with an electronic trigger, which due to the lack of drag against the advance unit required making the springs more effective by rotating the plate, and I have also reduced advance range for use with points by adding a dab of weld to the resting side of the hole to give max 30 deg crank advance for higher compression motors. Very easy to play with.
Click to expand...

Hi Tippie!

Wow, so simple solution... I didn?t think about it! I rebuilt the advance system completely (clean and grease all moving parts) the idea of giving the springs a few extra turns sounds like an original solution, I?ll try it. otherwise Ernesto has a new advance unit, and a Sachse system will be in my shelter looking at me: ?you know what you have to do?

Miguel
 
michipons said:
I have attached in the first message the wiring diagram... in case somebody wants to check it, funny thing is that in two different diagrams I have, the blue light is connected to the low beam circuit!
Click to expand...

Yes.  You're right.  Wiring diagram shows the blue 'high beam' light connected to the low beam circuit. Well spotted.
 
Then I will leave it like it is, and when somebody says! ?Your light is not working as it should? I will say... sorry yours is wrong🤪🤪🤣🤣

Interesting thing is that I have seen already two diagrams with the same distribution.

Miguel
 
Miguel, is it showing too much advance at idle or when you rev to max advance? I can't recall if the springs begin to allow advance at idle or a little after. But it is a very simple advance unit to check and modify - as Tippie points out (no pun intended!).
 
My SF2 had the high beam control light on when low was on when it still had the original loom. Corrected it when I made a new, and substantially smaller, loom.

 
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