@dryballs @GLscoot @victor @shamrockexpress
Sorry to be digging up a corpse here, but I'm new on here and I find this... Impressive!
I'd like to introduce my approach to a reed-valved SS180 -> SS228, this is the engine that actually inspired the Pinasco-kit via Andreas Nagy, best known for developing and distributing the most brilliant WF-kits.
Difference is: I went all out where Pinasco is cutting corners...
The idea was to revive the old blue prints from Arthur Francis' SS250 Manhattan, which was stopped in its tracks due to components of inferior quality available in '66. That quality can be found today. So with that inspiration in mind I set out to design the engine with a few cornerstones of my own:
Roughly double the power considering-
1.) maintaining and enhancing the original characteristics (the GS/SS-feel), such as agility and stability, keeping the allrounder qualities for city, sports (!) and touring in a decidedly torquey design, with performance peaking at the SS-typical 6250-6500rpm.
2.) original appearance by look and sound.
3.) reasonable fuel economy
4.) absolute robustness in any situation for many years to come.
So after years of looking for a suitable donor (screwed GS/SS engines are the proverbial hen's teeth, the just don't break!), I found one and set out using these parts:
-Malossi Sport 2013, rewelded to take a bespoke reed valve box for
-a Malossi V10 flat (not V-shaped) reed valve to ensure a snug fit of the SI27/23 in its original location. (Notice for the alert reader: Yes! This is the restrictive point in the system, limiting the potential of the Malossi Sport- but I was never going to go up to 30bhp anyway, and I certainly was not going to sacrifice the seat of the carb.
. I could of course chuck it out and go purely piston ported with a considerable gain in power, but that would corrupt the fuel-economy considerably. So I see this as a perfect solution for this prototype with its specific conditions. After all, having calculated the flow capacity of the V10 in relation to the 27/23 carb, this compares near exactly with the street racer characteristics found on the legendary RD350, for example. Works for me!
I'd be happy to answer any questions regarding this issue)
-a number of oversized jets for the otherwise standard SI27/23
-a bespoke (tapered) polyamid distancer between carb and barrel, as a suitable heat barrier as well as for the snug fit again.
-a superior DRT GS/SS clutch (max. version Ø115mm, using 14 out of 28 possible coils), feat. 23 teeth instead of original 22, increasing the transmission from 3,05 to 2,91 (ca. 5%).
-a hardened gear selector coil
-a SIP-Road 2.0, rewelded to fit between frame-fixingpoints and Malossi exhaust port.
-a bespoke crank, based on a MEC-EUR SS-repro, but with a hardened Suzuki shaft, laser welded top and botton, silver bearing, and longstroke crankpin (62mm total).
-a Vespatronic had been installed initially but was soon discarded in favour of the original points ignition. This was done because the very revvy flywheel and variable ignition points ruined the desired SS-feel completely!!! And it looks like sh*t, too! Currently waiting on an LTH-announced SS-adapter for the static electronic Vape PX-ignition, just to try it out, but the points are just fine, really!
I don't think I've forgotten any components, really... It's been a few years, but the gearbox, kickstarter mechanism, etc., etc. are all original in their near indestructability.
The block was adapted to take the PX-Malossi (studs renewed, one of them moved in its position), and was also welded to have the porting shaped accordingly. Pre-compression slightly increased (3-4%)
Result: Mission accomplished! Looking absolutely stock, bar the SIP-road, ca. 19 bhp/24 Nm on the rear wheel, consumption less than stock, rocksolid Sports-Allrounder with all the GS/SS quilities kept or enhanced where applicable... Just a lot of fun!
Early vid on Worb5's open day, stupid, revvy, Vespatronic to be disregarded, please:
https://youtu.be/sXtY_fnnpLE
