Actually @PosiMo_Andy and I talked about this a couple of weeks ago. 
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I think the reason tyres ‘feel’ less grippy today was the change from natural rubber - remember the graining and marbles and rubber buildup on the circuits in those days, to a ‘synthetic’ plastic like rubber tyre. It doesn’t have the side grip or braking traction are way way down, nor does a track continue to accumulate rubber once the racing line is cleaned up. I raced leopard in Australia in 2002-2006 and the older MG Yellows were so so grippy, came back in 2012 in X30 with new MG Yellows and couldn’t believe the difference in feel, although laptimes were reasonably comparable.
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There was an EU law that came in to limit PCA additives in 2010, is that what you’re thinking. I had thought it was CIK-FIA driven, when they started homologating prime and option tires for the KF classes.
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Apparently the direct-drive days were fun for blowing motors at 20K. Since direct drive (no clutch), its a lockup at full tilt. James has some videos of a mad irishman locking up a DD most spectacularly.
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You should know better than to get me started on this 
Yep. 100cc direct drives was a good time if you’re a masochist. Aircooled 100’s liked to lock up on the regular. Carbing was a real skill and tactic during the race, esp with the jet screws right by the drive sprocket.
One time I locked a motor so hard I flat spotted a new set of tires (a rare treat) then snapped the chain when the kart finally did a 180.
Sorry to necro this. Reading your comment reminded me of a concept called min-maxing that I am experienced with through gaming. Typically involving great expense in $ or time, being “required” to find every possible edge. This idea of hauling around 50 engines and changing engines mid-practice reminds me of simultaneously running three player accounts to fortify my assassin with every possible offensive and defensive buffs prior to combat. Completely nuts, but if you were a top player in PvP, it was a requirement. Weirdly enjoyable, in an elitist and power mad way.
It’s all good, it’s not really a time/age sensitive topic… Plus I think I necro’d it when I moved the posts above.
Since we’re necroing this post, can you take a FA and make it into a FSA engine? I’ve been wanting to get an FSA engine just for fun, but I know nothing about them
Yeah they are more-or less identical. Primary difference is the carb size. Carb for FA has to be a 24mm butterfly, FSA can use up to 30mm slide. Ideally there would be port changes too, but often they would be made during the event for the track and relatively minor.
The bolt spacing for the two carbs is the same (Tillotson HL pattern), you may have to open up the inlet tract for it, but generally they are big enough to use a 30 with anyway. You could probably also use a super KF carb too.
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Yes and no, some of the FSA engines where very different from there equivalent FA engines. FSA wasn’t homologated and the regulations where freer. So I know of cases of FSA engines which looked like one engine on the outside but were a full copy of another engine on the inside.
But you’ll get most of the fun with the carb. Bore it 135cc for Formula K style fun 
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That sound!
Some good tech info here on 100’s
My winter project turned into a first sunny day project.
I was looking for a pre-2k birel last year for a recreation of a particular kart and came across this 02 homologation chassis on craigslist.
It was fitted with a KPV motor and came with a box of spares. In the box was an unused comer 351 100cc reed valve motor!
It’s on its first piston , everything seems not to be even run in!
I had my old carb sent over from home (Ireland), just need to source an exhaust now.
Looking forward to blowing the cobwebs off it in newcastle as soon as we can get out there.
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I thought I recognized the name. I think I knew your dad.
Nice. I had a Woltjer Comer 351 and 2 DAP T85s that I raced in Germany in the South German Championship last year of the aircooled engines. I also raced them the first year of the watercooled engines '00 but the water cookers were .2 faster on most tracks.
I would love to get one again.
Put a 29mm slide carb on my rotax dsc and got an extra 600rpm over my 24mm butterfly on the same gearing
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Talk about a deal. Chassis look practically brand new.
Also looks like a Q31, which was a great chassis!
No clutch, direct drive. You spin, you stall. Get out and push.
This is the thing for me. I personally think it made us better drivers too. Less bumping etc and you knew that if you spun not only was your race done, but you had to push start the damn thing too, which isn’t easy.