If you have an old rotary valve engine that deserves to be restored
contact me. I am really good at it and very particular.
100cc Air Cooled Rotary Valve
Stroke: 53.8mm
Rod length 100mm
Bores Size: 48.29mm
Piston Size: 48.20mm
Clearance: 3.6 thou
Exhaust = 174deg
Transfer 127deg
Boost = 125deg
Valve close = 65 deg
Valve Close = 125 deg
RV clearance = 12 thou
End Play = 8 thou (crucial with angular contact bearings)
Timing = 2.3mm
Squish = .85 mm
Combustion chamber = 6.9cc
Compression Ratio = 14.5 : 1
RPM limit 17,400rpm
Stroke: 53.8mm
Rod length 100mm
Bores Size: 48.29mm
Piston Size: 48.20mm
Clearance: 3.6 thou
Exhaust = 174deg
Transfer 127deg
Boost = 125deg
Valve close = 65 deg
Valve Close = 125 deg
RV clearance = 12 thou
End Play = 8 thou (crucial with angular contact bearings)
Timing = 2.3mm
Squish = .85 mm
Combustion chamber = 6.9cc
Compression Ratio = 14.5 : 1
RPM limit 17,400rpm
The SS20 was homologated in 1970.
Immediately World Champion. Dimensionally the same as made in 1984
with updated conrod, piston and bearings. Three transfer
ports, the third being fed through a window in the piston. People look back
and imagine that the karts of the
1970's were basic with much
less performance than todays 125cc water cooled beasts. I took this out for a practice session on a 1990 Tony Kart.
There were Evo,s, Leopards, X30's, KA100,s and
Shifters. This stock SS20 out ran them all in a straight line except
for the shifters. The Bridgestone tyres of 70's had a lot of grip and the Birel
- Deavinsons - All Kart - Swiss Hutless - BM - Sirio chassis etc were really
good. Very light, really quick.
I raced this engine only once, in the early 90's at the last round of the "Formula A" club championship. I had it in the bag having run unbeaten in the prior rounds with an Atomik AKV90. The track was run in reverse which meant that 30% wound uphill through 2 medium speed chicanes. This engine pulled 4 or 5 kart lengths on the Rotax's uphill with astonishing mid range. They would catch me at the end of the main straight. It was fun, fun, fun. Battled hard all day. The final heat I was on pole and took off with a good lead. It took the Rotax's a while to run me down and it was on. 2 laps to go the engine went off song, I lost 2 spots. The exhaust header had cracked at the flange. Sad. When I opened the engine at scrutineering everyone was shocked it was stock standard. Not visible was the perfect blueprint build.
We had 4 SS20's. Quick and super reliable to learn with. I took to one. Raised the barrel, eared and enlarged the exhaust port, the boost port, piston window and the inlet track to 70/130 valve timing with 15.5:1 comp. Competitive against the newest engines and even won a race meeting against a Sudam 125cc. Our driver was a more skilled than the Sudam driver (who was a dealer team driver with a new chassis.) The local dealers / tuners disliked these old engines winning. The pineapple Parilla, in its many forms, was one of the best kart engines ever made. I see that, I know that. Lake Speed forever.
I raced this engine only once, in the early 90's at the last round of the "Formula A" club championship. I had it in the bag having run unbeaten in the prior rounds with an Atomik AKV90. The track was run in reverse which meant that 30% wound uphill through 2 medium speed chicanes. This engine pulled 4 or 5 kart lengths on the Rotax's uphill with astonishing mid range. They would catch me at the end of the main straight. It was fun, fun, fun. Battled hard all day. The final heat I was on pole and took off with a good lead. It took the Rotax's a while to run me down and it was on. 2 laps to go the engine went off song, I lost 2 spots. The exhaust header had cracked at the flange. Sad. When I opened the engine at scrutineering everyone was shocked it was stock standard. Not visible was the perfect blueprint build.
We had 4 SS20's. Quick and super reliable to learn with. I took to one. Raised the barrel, eared and enlarged the exhaust port, the boost port, piston window and the inlet track to 70/130 valve timing with 15.5:1 comp. Competitive against the newest engines and even won a race meeting against a Sudam 125cc. Our driver was a more skilled than the Sudam driver (who was a dealer team driver with a new chassis.) The local dealers / tuners disliked these old engines winning. The pineapple Parilla, in its many forms, was one of the best kart engines ever made. I see that, I know that. Lake Speed forever.
