SF 1 infomation

Fitz

Fitz

Senior member
Location
Cheshire UK
Hello all, hope everyone is surviving the lurgy as well as can be expected

Couple of questions:-
1) Has anyone done a 530 to 520 chain and sprocket conversion on an early SF1, if so what engine sprocket did you use. I did this on my Monty racer, the engine sprocket splines are identical to an early Honda twin, the weight saving is significant and I can use modern chains and have tricky lighweight wheel sprockets made to order. Just took the rear wheel and hub apart on the SF, the sprocket is steel, weighs a ton and has crap machining, the chain could have held the Torre Canyon off the rocks

2) Has anyone done the swing arm bush to needle roller conversion on the SF, if so can you provide drawings or dimensions, again I did this on Monty racer and have details. The arse end of my newly aquired SF is waving around like Trumps hair in a breeze, wheel bearings are ancient so they are going, may as well do these two jobs at the same time while its apart

Any opinions on the Bosch ignition coils, I use Dynatek on my race bike and can't fault them, obviously the points ignition will be going, plug leads etc. If the Bosch are OK I may retain them but if they are suspect (and they are 50 years old) they may go as well. It also affects which ignition system I select, the pick-ups, electronics, coils and leads must work together

Just started looking at the rear brake which is huge, I've not looked closely yet, just ordering the wheel bearings, I can only see one operating cam, it looks like a TLS brake that somone forgot to put a link arm in

I have downloaded a really poor owners manual and parts list, is there a decent workshop manual available for download and a source of solid information

Lastly, I am dreading this one - paint codes for the cobalt blue colour, I found an endless thread arguing about such a lot of bollocks, its just blue, from around 1970

Thanks chums, oh by the way, if you are venturing out for the first time this year, please keep your wits about you, I took my big tourer out a couple of weeks ago and had two near misses, one was just " I knew you hadn't even looked for me you bastard" easily avoided, the second nearly had me off, the classic sorry mate, I didn't see you job, I had a massive headlight and two smaller side lights all switched on and the silly bastard still pulled out one me - give me strength

 
Hi Fritz,
I have ground my gearbox sprockets down to allow 520 chain to fit. Would be interested in knowing which early Honda Twin has the same spline setup?

By the way you planning at being at Pembrey  in July(25th and 26th) if BHR hold the event?

Andy
 
I did the bush to needle roller conversion on my SF2 early 90s.
You need the bearings and a new internal spacer.
Available as a kit from the usual suppliers. I wouldn't do it again, those bearings aren't very long lasting and need changing every 25 000km or there abouts. And yes, I do grease them.

There should be 2 arms, one short, one long, linked by a rod on the 2nd generation Laverda drum which is original on your SF1.

I've had one Bosch coil give up the ghost in 30 years and a lot of use.

If you want electronic ignition to replace a perfectly reliable system, it's your money.

There's only one parts list, you'll find it on Laverdamania, technical section.

The green book will be your workshop manual.

Paul
 
The Bosch coils are extremely long lasting, I never had one fail. Replaced them with a two pole mini Dyna when I went Ignitech as it has one pickup and a two cutout rotor. On my 270 I used 2 Dynas as I find the Bosch huge and always in the way.
There should be two (identical) cams that each shift the leading edge of a brake shoe.
Laverdamania when I access it now is all in French, no English flag. LavParadies has all the parts diagrams. The only time I look in my manual is for clearances, they are very simple bikes for a competent mechanic like you seem to be.
My needle rollers have been in for  decades and are still good. I just cut down the old spindle and used it as a spacer between the inners, machined to suit within the sides of the frame. Bronze bushes are stronger and last great if greased so if that's easier there is no benefit really it seems.
 
Drag the cursor at the bottom of the screen all the way to the right and you'll see the UK flag for English option.
 
The brake shoes are not operated by cams, neither on 1st nor on 2nd series Laverda brakes.
They are moved by levers , which are linked to the shoes with 2 plates and pins.
 
FITZ !

Are you going to run an SF? I've just bought a 750 to run in BHR BEARS F2 next year but need to start from scratch. I've never touched a 750 so will be starting from ground zero. It'll give me something to do over the summer.

Cheers


Gareth
 
Ernesto said:
The brake shoes are not operated by cams, neither on 1st nor on 2nd series Laverda brakes.
They are moved by levers , which are linkefd to the shoes with 2 plates and pins.
Click to expand...
Wrong term, a sort of lever, but work on the leading end of each shoe
https://www.laverda-paradies.de/shop-750-22-en.html
 
OK. Might be the wrong term. So I better use
photos to make it clear.
 

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No cams in a Laverda brake, only bell-crank levers.

They are a bugger to set up correctly, all slop should be removed.  Junk any old linings that may seem to be "OK" and have a known good type bonded on and machine the shoes to drum diametre.  This will result in a brake that works well from the word go, and won't require 2 decades of bedding-in...

Grinding gearbox sprockets is a pain.  I glow them soft, turn them down and re-harden.  Lots of scientific waffle to be found on this topic, but heating to cherry-red and a quick quench works well enough.  Bloody thing won't last forever anyway!

750 swingers (excepting SFC) have the same bearing/frame dimensions as the 180? triples, all bits are interchangable.  Needle bearings unfortunately don't last forever either.  Bushes are better, but are usually shot through "over-maintaining" ::) by now.  Nought wrong with the rubber bushes (if fitted) if they aren't perished, except maybe for racing.

piet
 
The SF rear brake is massive and totally unnecessary fro racing - why not go a much smaller drum rear hub, lighter, simpler, easy to find 17mm axle hubs. If you want drum to cover class regulations, that's the go, otherwise use a disc rear hub.

Didn't know I could buy a 520 sprocket for my bike - have a 20T that I'll adapt, but if I need a 19 I'll look at that L Paradies option ... if I can afford it!
 
An advantage of the 520 conversion is that you can use o-ring/x-ring chains
and they won't interfere with the housing.
So, if you machine a stock front sprocket down, be sure to machine from both
sides so that the remaining part stays in the middle.

Ernesto
 
Ernesto said:
So, if you machine a stock front sprocket down, be sure to machine from both
sides so that the remaining part stays in the middle.

Ernesto
Click to expand...

not if you use GSX-R-Rims though, as you need the extra mm for the 150 rear tire. in that case, only machine the engine side of the sprocket, but with the right angle...
 
I grind down the 530 g/box sprocket to make it a 520 - not too bad with a toolpost grinder. - Regards - Phil
 

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Laverdalothar said:
not if you use GSX-R-Rims though, as you need the extra mm for the 150 rear tire. in that case, only machine the engine side of the sprocket, but with the right angle...
Click to expand...

A 150 tyre on a machine putting out 45 hp at the rear wheel?
The amount of power a tyre like that absorbs wouldn't leave anything for propelling the machine forwards.

Paul
 
Hello again, thanks for all the fun and information, hello Gareth, good to hear from you, cant belive we had the same idea - AGAIN, great minds eh'

I found the other brake arm - it was on the end of the brake cable, the wheel hub etc were on my bench - mystery solved

I wanted to build a 750 to go into F2 Class in the BEARS race series, however this bike has a documented history linked to the Laverda family and is a drum brake model. It also has a lot of charm despite years of abuse so I am undecided about putting it into racing but we will see. I've had various stories saying the drum brakes are known to fade under heavy use and when I asked people that are serious racers about the brakes they went UUMMM

The sump plate was smashed on two corners so has already been replaced, the rear wheel is waiting for the new bearings having been in my vapour blaster. The shoes are in good shape but I have a local guy that does race compounds for replacement shoes and sets up drum brakes for the classic car racing crowd, I will be talking too him this week

Now I have the replacement sump plate, I can put fresh oil in connect the new battery and see what lights up, the wiring is pretty shabby. I've already vapour blasted and ultrasonically cleaned the carbs, usual story blocked jets and emulsion tubes. I want to see how the engine is before I commit to anything

I will have a think what the future holds for the bike before I commit to tyres, it has Borrani rims front and rear - dont know if that is standard

The swing arm needs sorting, bit surpised to hear somebody has failures of needle rollers, my Monty has never been touched since I did that, but I suppose it does not do high miles

I am told there a lot of rare parts fitted, the brake hubs have air scoops to drag air into the hubs and brakes, all patented Laverda designs I am told

I will need to do the clutch conversion if the current effort is standard, you wouldn't last more than a few laps or miles before that got the better of you. If it is right - what the hell were they thinking

I went through the same with my little Velo' I bought a 350KSS Mk2 for another class of racing but fell in love with that too , I dont mind sliding off it but the thought of lunching an 80 odd year old motor or gearbox was too much, so it is now road registered as well and I blast around Cheshire and the Derbyshire peaks on it

Always glad to hear about racing tips or improvements we can make - thanks again chums
 
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