This magnet thing is becoming a bit of an issue,thats 2 or 3 out of probably dozens that its happened to but its a bike stopper when it happens, there has been some thought put into a mount that has the magnet inserted so it won't come adrift.Don't know how far they got,seems there isn't much room to go in behind.Maybe we need an engineer?
Re: What did you do to or for or with your Laverda today?
- Thread starter Paul LeClair
- Start date
Dellortoman
Hero member
- Location
- Tasmania, Australia
Vince said:
Or a mechanic
I presume the rotor design was inherited from Sachse. It's becoming evident to me that mounting magnets in holes drilled radially on the outside of the rotor has its problems.
The tiny little magnets weigh bugger all, but they're apparently heavy enough to be flung out of their holes when the revs get up a bit. It must be like a fucking centrifuge in there. Drilling the magnet holes parallel to the crankshaft would be a better idea, but would require a re-design of the pickup board. Maybe Lex is up for that, but I'm not.
I'm wondering whether epoxy would hold them in place, but perhaps it's been tried and failed.
At least the escaping magnet doesn't appear to have taken out one of the pickups this time.
I thought that the optical sensors were an issue with the Series 1 engines,oil on the sensor on occasions.Having the magnet come off happened on one of our breakfast rides to one of the bikes and there was some talk about looking at a better fixing,that came from someone with the gear to maybe fix it.Haven't heard any more though.Thats 2 bikes out of lots running them so statistically its 2/5th of bugger all,
but like I said its a bike stopper if it happens.
but like I said its a bike stopper if it happens.
D
Davo
Guest
AndyW said:
And traveling at about 175kmh...
Vince said:
That's why the great majority of hall sensor systems have the magnetic sensor stationary...
The optical sensors do have their problems, but these usually only set in after many 1000 kms or 10-15 years of use. Easy and cheap to replace as a matter of course. Easy to carry a replacement when on a long trip, too.
Mr.Witt is currently developing hall sensor and rotor systems to replace the optical triggers of the DMCs. Re-vamp of the entire DMC range due mainly because many electronic components have become obsolete.
piet
D
Davo
Guest
sweetas said:@ ~25000 rpm.
@9000 rpm if the rotor is 10cm dia. so just guessing really.
Volker Sachse original electronic ignition systems were Optical but he changed to Hall Effect due to reliability issues, mainly due to temperature related failures
John Wilson's IIS systems were also first produced with Optical triggers and he also changed to Hall Effect for the same reason
we have sold roughly 600 ignition systems worldwide since Volker died and we were forced to make our own ignitions, from that we have lost 6 magnets, all in the last 6 months after I bought a new bottle of Loctite glue stuff as figured my original bottle may be getting past it's shelf life, bad mistake
have replaced all damaged ignitions free of charge, even replace the systems free of charge even when they are installed wrong and burnt out or damaged by the owners
doubt very much we have even made a profit this last year on ignitions and I'm totally over making them, recently started telling prospective buyers to go and buy a DMC if they want a Series 2 or 120 system especially if it is an overseas query
John Wilson's IIS systems were also first produced with Optical triggers and he also changed to Hall Effect for the same reason
we have sold roughly 600 ignition systems worldwide since Volker died and we were forced to make our own ignitions, from that we have lost 6 magnets, all in the last 6 months after I bought a new bottle of Loctite glue stuff as figured my original bottle may be getting past it's shelf life, bad mistake
have replaced all damaged ignitions free of charge, even replace the systems free of charge even when they are installed wrong and burnt out or damaged by the owners
doubt very much we have even made a profit this last year on ignitions and I'm totally over making them, recently started telling prospective buyers to go and buy a DMC if they want a Series 2 or 120 system especially if it is an overseas query
I feel like a bit of a ---- ,a tiny hiccup and I want a Royal Commission.
I hope I haven't detunned your great work Red, who else stumps up for this stuff expecting to cover all bases and get blind sided by something out of your control.And then have it cost time and money.And its far from the only time.Owe you a Berbon in a few weeks. Sorry mate
I hope I haven't detunned your great work Red, who else stumps up for this stuff expecting to cover all bases and get blind sided by something out of your control.And then have it cost time and money.And its far from the only time.Owe you a Berbon in a few weeks. Sorry mate
Dellortoman
Hero member
- Location
- Tasmania, Australia
Gotta say I was in no way criticising Red's product or service. He has provided a good system and excellent product support.
A lot of the stuff Red does is cutting edge development and it's only to be expected that there will be a few hiccups along the way. If nothing ever buggered up, we'd never learn ways to make it better. At least he's having a go at upgrading the ignition technology for these old bikes. From comments here, it seems the failure rate of these Sachse type magnetic rotors is pretty low. I've just been unlucky in that I've had it happen twice in a short time. But this is a race engine that regularly gets revved beyond 8000, so I'm probably pushing the limits of this type of ignition rotor. At least an escaping magnet doesn't trash the rest of the engine, so no harm done.
I reckon I have a workable solution that will keep the magnets in place. I'll give it a try with my rotor and make up an adaptor so I can test it to 12000 rpm on a 4" angle grinder. For safety, I'll put the rotor inside a tin can before spinning it up to 12000.
For those of you interested in the G-force:
Rotor diameter 50mm. So at a speed of 9000rpm, the speed at the outer edge is 85 kph and the G-force is 2264
G-force is proportional to the square of the speed, so at 12000rpm it's 4025 G
(G-force calculator for dummies here http://www.endmemo.com/bio/grpm.php)
I'd estimate that the magnet weighs about 1 gram*, so there's over 2kg trying to pull it off the rotor at 9k revs, and 4kg at 12k (my proposed test speed). It's not surprising that an occasional one lets go.
If you think those forces are high, have a think about crankpins and webs, primary chains, etc. It's hundreds of tons - scary
*The magnet weight doesn't register on my digital kitchen scales which have 2 gram resolution, so its weight is somewhere between 0 and 2 grams.
A lot of the stuff Red does is cutting edge development and it's only to be expected that there will be a few hiccups along the way. If nothing ever buggered up, we'd never learn ways to make it better. At least he's having a go at upgrading the ignition technology for these old bikes. From comments here, it seems the failure rate of these Sachse type magnetic rotors is pretty low. I've just been unlucky in that I've had it happen twice in a short time. But this is a race engine that regularly gets revved beyond 8000, so I'm probably pushing the limits of this type of ignition rotor. At least an escaping magnet doesn't trash the rest of the engine, so no harm done.
I reckon I have a workable solution that will keep the magnets in place. I'll give it a try with my rotor and make up an adaptor so I can test it to 12000 rpm on a 4" angle grinder. For safety, I'll put the rotor inside a tin can before spinning it up to 12000.
For those of you interested in the G-force:
Rotor diameter 50mm. So at a speed of 9000rpm, the speed at the outer edge is 85 kph and the G-force is 2264
G-force is proportional to the square of the speed, so at 12000rpm it's 4025 G
(G-force calculator for dummies here http://www.endmemo.com/bio/grpm.php)
I'd estimate that the magnet weighs about 1 gram*, so there's over 2kg trying to pull it off the rotor at 9k revs, and 4kg at 12k (my proposed test speed). It's not surprising that an occasional one lets go.
If you think those forces are high, have a think about crankpins and webs, primary chains, etc. It's hundreds of tons - scary
*The magnet weight doesn't register on my digital kitchen scales which have 2 gram resolution, so its weight is somewhere between 0 and 2 grams.
AndyW
Hero member
sweetas said:
Ah, ok I was thinking of the alternator rotor (doh!), so that brings it down to a more manageable 60kmh and ~1630G...
Working on the given dimensions above:
linear speed (v) is 0.036 x ∏ x 9000/60 m/s (or 0.036 x ∏ x (9000x60)/1000 km/h)
Angular velocity is 2 x ∏ x 9000/60 rads/s (ω)
G = vω/9.81 = (16.985m/s x 942.5 rads/s) / 9.81 (9.80665 really) = 1630 G
Still enough G to make you dizzy... ???
chrisk
Hero member
- Location
- Brisbane, Australia
AndyW said:
If Moose hadn't banged his head on that bloody screen turret on the way out, he could've handled 1630G.
Iceman, only thinks he could.
GregT
Hero member
- Location
- Christchurch NZ
Does it actually need to be a magnet ? I'm asking cos I've used hall effect sensors on several motors with plain mild steel triggering pieces.
One in particular used an alloy center piece with a 3mm thick short strip of MS screwed to the outside.
To test if it has to be a magnet, simply touch a non magnetised screwdriver to the sensor, it should in my experience anyway, spark at the plug when the screwdriver is pulled away.
One in particular used an alloy center piece with a 3mm thick short strip of MS screwed to the outside.
To test if it has to be a magnet, simply touch a non magnetised screwdriver to the sensor, it should in my experience anyway, spark at the plug when the screwdriver is pulled away.
Put the SF2 in the second garage for winter overhaul on Saturday and went to pick up my new Aprilia Shiver.
Did 200km on it yesterday. The first surprise was the fierceness of the front brake. Got to be mighty wary.
The engine is lovely. Quick to rev, powerful, enough vibration to make it present. Engine electronic management not good at low revs, engine hunting, uncomfortable in town.
Hydraulic clutch is pretty heavy, much more so than the cable clutch on my friends Triumph Street Twin which is a lovely machine but not italian.
Off work most of next week, so will service the SF.
Paul
Did 200km on it yesterday. The first surprise was the fierceness of the front brake. Got to be mighty wary.
The engine is lovely. Quick to rev, powerful, enough vibration to make it present. Engine electronic management not good at low revs, engine hunting, uncomfortable in town.
Hydraulic clutch is pretty heavy, much more so than the cable clutch on my friends Triumph Street Twin which is a lovely machine but not italian.
Off work most of next week, so will service the SF.
Paul
a14rgs
Hero member
- Location
- Wiltshire, UK
Dragged the RGS out the garage and took it for a photoshoot for a forthcoming article in Practical Sportsbikes mag on long-term ownership / high-mileage bikes. Apparently 27 years and 148000km fits the bill (and, more importantly, it's another Laverda magazine feature) 8)
April issue, going to print on Friday, so due out soon....
April issue, going to print on Friday, so due out soon....