Pazon ignition for Laverda SF 750

corsaro

corsaro

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York UK
I am now rebuilding a 350 and 500 Laverda - interesting ...... just searching for valve buckets of 25mm but discovered that valves from a rover car seem to be virtually the same as the exhaust valves for the 500 just a lot cheaper than laverda ones - if you can find them, now searching for other equivalents .... but for several years (14) I owned a 1972 750 SF1 and could not get the bike to run well at idle or from idle through the rev range. I determined after all other settings were to spec that the problem was the auto advance unit combined with the Bosch points system .When I checked the ignition with the strobe it was evident the timing was moving around and off/on when revved hence I fitted a pazon system- initially intended for I think a 360 degree Triumph twin. The system Just needed a few parts making, an adaptor for the trigger, a backing plate for the pazon circuit board and a mounting plate for the pazon control unit..I also installed compact coils so the installation was quite small compared to the original setup.
The results were very good, a rock steady idle , excellent smooth pick up from 1500 revs through the rev range and an improvement in fuel consumption. It transformed what was an already good bike.

Here's a library link to the description of the system and if anyone needs them I have drawings of the parts.

Stu
 
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Not doubting your bad experience with the std SF ignition system but plain fact is that many tens of thousands of SFs over several decades performed faultlessly (my SF1 included) on the excellent Bosch coils, points and advance unit. I've progressed to a modern Ignitech but as a mechanic if I came upon an SF with issues such as yours I would persevere until the cause was found.
 
I agree with Quentin. With my SF1 I stayed with the points in the 16 years lasting ownership.

You have taken the trouble now to adapt the ignition of a related parallel twin for the Laverda. For this you'd to buy and then modify it for the use on the Laverda.

I'd rather had oriented myself more towards a solution that was originally been developed for a Laverda. In my latitudes a DMC probably ...
 
My 750s apart from the Electronica of course all run the original system. Between them, they do about 10 000 km annualy without concern.
If the auto advance is cause for concern, if it can't be fixed, change it.
Everybody is fitting electronic ignitions so there are plenty of spares.

Phil Todd used Boyer on 750s.

Paul
 
I fitted a Boyer system (basically the same thing as a Pazon since the Pazon guys all worked at Boyers) intended fo a Norton Commando in 1977 to my Egli SF, there was a lot to be desired and it was a very easy fit, but the advance was inadequate for the SF, never a problem if you did not exceed something like 5000 RPM, buy this was a RACE BIKE! all it needed was a racer on board!
CLEM
 
CLEMTOG said:
but the advance was inadequate for the SF, never a problem if you did not exceed something like 5000 RPM, buy this was a RACE BIKE! all it needed was a racer on board!
CLEM
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What was the inadequate advance Clem? My race SF uses 29 deg max advance. Dyno runs showed anything more had no benefit whatsoever. I run the same on the road SF which has the ex racer Mondial pistons that give it 10.5:1 compression and it goes great.
 
Some tired engines the oil pump drive spindle, on which the whole ignition is mounted, has play on the bronze bushes in the crankcase, resulting in the ignition timing being all over the place when using the points ignition. On such engines an electronic ignition is much less affected by the play.

Marnix
 
MarnixSFC said:
Some tired engines the oil pump drive spindle, on which the whole ignition is mounted, has play on the bronze bushes in the crankcase, resulting in the ignition timing being all over the place when using the points ignition. On such engines an electronic ignition is much less affected by the play.

Marnix
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This is not a points thread.
A knackered and worn engine is knackered and worn whatever the ignition.

Paul
 
I fitted a Wassell Vape electronic ignition (Triumph/ BSA) to my SF3. There's 20° advance and I've set full advance at 34°. It starts on the button and runs perfectly. Best thing is I haven't touched it in 6 years.
 
MarnixSFC said:
It’s very much a points ignition related thread, hence my remark.
It’s very common to overhaul an engine and overlook the play the oil pump shaft has on these bronze bushes, especially when using your beloved points ignition.

Marnix
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It's very common to overlook almost everything on most overhauled engines.
But point nonetheless taken.

Paul
 
natm said:
I fitted a Wassell Vape electronic ignition (Triumph/ BSA) to my SF3. There's 20° advance and I've set full advance at 34°. It starts on the button and runs perfectly. Best thing is I haven't touched it in 6 years.
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The pazon system I initially set at 38 degrees but with the addition of 10% ethanol in fuel a better setting was 35/36 degrees. I ran the SF1 in France on 15% ethanol and this setting was still ok but 34 degrees would probably have improved it yet again. I have a velocette Venom to which the Pazon is fitted and likewise transformed the bike mainly due to the predictable and consistent advance curve, the fully advance setting was likewise adjusted for the ethanol.The main advantage of both the Pazon and vape system appears to be price - the DMC/Witt system seems to be around £650 in the UK whereas the Pazon is at present around £150 and presumably the vape is a similar cost. I initially fitted the Pazon as a trial to see if the SF1 could be improved and subsequently left it in position as a permanent fixture and did not touch it for the next 10 years of ownership.
 
corsaro said:
The pazon system I initially set at 38 degrees but with the addition of 10% ethanol in fuel a better setting was 35/36 degrees. I ran the SF1 in France on 15% ethanol and this setting was still ok but 34 degrees would probably have improved it yet again. I have a velocette Venom to which the Pazon is fitted and likewise transformed the bike mainly due to the predictable and consistent advance curve, the fully advance setting was likewise adjusted for the ethanol.The main advantage of both the Pazon and vape system appears to be price - the DMC/Witt system seems to be around £650 in the UK whereas the Pazon is at present around £150 and presumably the vape is a similar cost. I initially fitted the Pazon as a trial to see if the SF1 could be improved and subsequently left it in position as a permanent fixture and did not touch it for the next 10 years of ownership.
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Where did you find 15% ethanol fuel in France apart from the local café?

Paul
 
I dug out some old records, max advance with the Boyer/Norton Commando system was 28 degrees
750SF as stock with points, very low mielage unworn engine was 40degrees (!) but it ran well at 36 degrees, no more needed.
These are my own figures taken using a Snap On strobe with variable advance measure.
28 was certainly inadeqaute.
CLEM
 
I’ve been running a Boyer trouble free in the white SF2 for over 25 years and it’s been in my Egli for another 10+ years. The trick is to give it some advance at idle, which surprisingly makes the engine idle better than at TDC.

Marnix
 
Paul Marx said:
Where did you find 15% ethanol fuel in France apart from the local café?

Paul
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Ha ha ha...........Haute Savoie, Samoens local supermarket, along with 65% ethanol pump with a warning that it may harm engines not designed for it..... did not risk it on my 56 alloy engined Triumph T100.... or the Morini 125 from 1959.....
 
E85 in the US is popular with the forced induction crowd running high boost levels. The problem is that unless you buy real racing fuel the ethanol content can vary from 51% to 85%! That’s OK if you just slap a blower or turbo on a junkyard LS or Hemi, but not so good on a true built motor tuned to get 1000+hp.
 
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