SFC Dyno Number?

V

Vince

Hero member
Anyone ever run an SFC twin on a Dyno, seems that happened recently on Head Kick and the number for it is Quote,

This was an academic exercise for me as I put mine on the dyno today and wanted to see how it compared to others. Got 59 HP and 46 lbs torque. I believe the equipment and operator are in good
 
It was a question posted on Zucerburgs nightmare, Laverda Riders Worldwide group by one of the Yanks, who I think did the last reunion at Briganzi party. Bloke called Rick. 50 grand bikes I don't own sadly. I do like his Mark 5 Motod though. He got the usual lecture about numbers don't mean anything, except if you're comparing Apples with Apples it's an easy way to see if your Apple is rotten. So that's the number with the bike idling well and running fine and he was asking about other SFCs with dino numbers.
 
The later 750SFCs were quoted by the factory at 75hp, at least that is what was stated in the brochures and in the rego papers.  It tallies with what we got on the Moto Witt dyno when we ran a '74 SFC, before we went to tuning it.  When we were finished, we attained a surprising 85hp and over 80Nm of torque, which is absolutely fantastic for a carburetted 750cc engine.

Most of the gain came from a rather expensive gas-flow session, we reckon it was worth every penny.  The lubrication system was entirely reworked, with a monster oil pump to get the oil flowing.  The bike was a really strong runner and extremely reliable, in sharp contrast to before, where it would eat cams and rockers for breakfast.

piet
 
I remember reading that they would go through all the parts on the line and select the best for SFC assembly, how true was that.
 
That?s what they did with the first series which were usually built three bikes or so at a time, but the 8000 batch already was production line work. They did put a lot of energy in balancing though, and, of course, polishing cranks, conrods etc.

Marnix
 
OMG.... again the dyno number discussion... The first thing to ask is: what did the operator do, how did he measure the power and which correction factors did he add, if any.

59HP sounds right for PURE BACKWHEEL power with no correction at all, assuming it is a very well running SF1 like the one of my passed away good friend J?rg Laden. I was wittnes of that dyno run years ago, unfortunately I think it is not available as video anymore. Or the backwheel power maybe of a true SFC which is not fully at max setting- or tuning-wise. If it would be corrected values and it was a genuine 750 SFC, I would try to find the fault...

@Piet: are you refering to Gregor's former 750 SFC that was afterwards in the hands of Joost and which he sold again some years ago? If so, that bike was massively reworked with something like 2.000+ hours to achive that result...

Andy Wagner's results I suppose were from his race-projects with Down-Draft head modifications, which all turned out to be total crap (measured on a flow-bench and compared to standard Laverda-heads, they had massive reductions of air flow, which caused him to give up on all his attempts with that down-draft approach).
 
Lothar,

Please take a peek at the topic header... :D

Yes, Georgs' ex.  Dunno if it was 2000hrs, could be.  Bike went like shit off a shovel, best example of a road-going SFC I've ever had the pleasure to ride.  Was still a pita to ride though, even back then when I was 25kg thinner. :D

piet
 
Too true Lothar. I've made this point at least once before. Having worked for several years in the late 70s in a WA moto shop (WA Yoshi/Moriwaki, Laverda concessionaire and Kawasaki dealer) with the only dyno back then in the state, I can only say that HP and torque figures for practically any dyno are probably best used in reference to other bikes measured on THAT dyno. Our figures were always 'low', but we had a clear picture of what was happening by comparison with other bikes.

For example, a std Z1 Kwaka after a full tune would produce anywhere from high-40s to low-50's hp at the Rr wheel, but a fully worked Yoshi/Mori'd motor with CR carbs and race pipe would produce 80hp. We weren't very scientific in the way we used it and it was basically a max power measuring tool. Customers would be disappointed until we explained the relativity factor. The owner of the shop was somewhat surprised when my SF1 (after a full top-end rebuild and valve seat 'rework') produced 45hp. I wasn't - it was a fast bike on the road.

So the figure for the SFC is only relative to other bikes measured on that dyno.
 
Maybe Red can get some comparative figures off his dyno guy if any of the hotted up twisted twins were run. We know his race bike has been well documented. Once my 880 is up and running I'll have it dyno'd for jetting and setup generally, but doubt the figures will mean anything to anybody unless I reference them to other bikes run on that dyno.

Piet, wouldn't it make sense to 'on-sell' some or all of that SFC setup to other SF/C owners? Recoup some of the investment!
 
Vince said:
It was a question posted on Zucerburgs nightmare, Laverda Riders Worldwide group by one of the Yanks, who I think did the last reunion at Briganzi party. Bloke called Rick. 50 grand bikes I don't own sadly. I do like his Mark 5 Motod though. He got the usual lecture about numbers don't mean anything, except if you're comparing Apples with Apples it's an easy way to see if your Apple is rotten. So that's the number with the bike idling well and running fine and he was asking about other SFCs with dino numbers.
Click to expand...
My first question is who prepared that bike & is it set up properly? Rick had some heartache with the MOTODD....
 
There was some mention of valve to piston contact with the Motod at some point. As I said he has fine taste in bikes.
 
sfcpiet said:
Lothar,

Please take a peek at the topic header... :D

piet
Click to expand...

Well - how many "750 SFC" replicas do exist - who knows if it was a genuine 750 SFC tested or a replica wich was assumed to be a "real" 750 SFC... ? ;) I don't know Vince in person nor do I know the bike. That is why I answered the way I did.
 
found a video, but I think the result of 56 ps is the result of the addition of measured power and estimated loss
as this is most common
https://youtu.be/ituseWgqjzI
 
That is the video! Thanks for sharing. On the left you see the unfortunately passed away J?rg Laden (man, I miss you... ), then owner of the bike (sold it some years ago to a collector, who just stored it in his collection...  ???). Guy in the military Jacket is Markus.

As far as I remember, the 56HP were without correction factor, which whould fit to the factory claims of 66 HP (according to JLO's "MINIBOOK"). The bike was really fast and very lify on the throttle  ...

I was holding the camera btw. and some of the comments are from me, too... ;-)
 
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