Scooterotica

standard vs fastfrogged

this is looking awesome

need to dig the b-p a bit deeper, but i'm on track.... I'm about to receive a pipe-design flange, first part of the formidable "S-box original fuer lambretta" a piece of krieg!
I've had several P-D exhausts and each time it was a all complete crasiness....

Ok i've begun to strip out this old and rusty engine. First surprise: a motoplat point ignition fitted on....



I never could released the stuck piston from the barrel. Got me a hack saw and cut the con rod!!



What should I choose for a clutch kit to cope with almost 20 hp?? 4,5 plate?

I like my SSC clutch in the imola.

thanks. I'll give a look.

Things are slowly going on.

all bearings are now removed. Cylinder soon to be rebored.
I've begun the crankcase porting/ digging, knowing that my 60mm crank needs some more room to spin freely.



gearing ratio is 15/46 and SX gears/cluster for a final ratio of 4,82. Seems OK for me. Sliding dog damaged but gears as new, chain's dead.

back to the o-tuning stuff.
I've been reading lots of threads about LPC vs HPC and I must confess that on my previous works on vespa ( T5 especialy) using a flowed and tapered crank with a bolt on MRP R-block, large crankcase transfers, 6 mm packer made performances very high... I guess PC was quite lowered down and a bigger volume was avalable for fresh gaz at each circle, literaly sucked by a well designed pipe.
Just a few pics "in progress" to refresh (my) memory:






This o-tuning project is far from our T5 racer but some ideas could survive. As it's been told: 200 engines were originaly designed from 125/150 case/barrel and PC increased to a dangerous limit as cubic capacity raised too. At low revs part of the fresh gas is just thrown in the exhaust by this too high PC. Just a waste.... Reducing PC will allows gaz to scavange burnt gaz as they should do and stay in the cylinder till exhaust port shuts whatever the counter pulse given by the exhaust. Exhaust tuning will occurs later in a much usefull way...
Bigger transfers, empty space given by the LTH bolt-on reed block and a simple "non full circle" meceur crank will help reducing a bit PC and give a better torque spread all over the rev range. The 2 boost ports will also help sucking this load of gaz compressed between reeds and piston skirt. Less primary compression is more fresh gaz to be pumped by the pipe.... A good way to raise your power output on a modest 2 port iron barrel

great topic /thread this ..its really interesting..

Same pleasure for me reading your posts SBS... Great deal of informations, top tuning tips and pics of "ueberarbeitet" RB....
Just for a digestive stroll: pics of my last non lamy project: LML/quattrini suppose to replace our (almost late) T5 racer. New race season and new engine on the bench.
Hope you'll enjoy it:



tapered crank and feeder:



"work in progress" of the 2 direct feeders:





flowed and tapered crank:



before cutting obstructive part of the spigot: one can see clearely feeder:



other side feeder (unclearely):