2014 Speed Week

Vespa Labs Speed Week 2014 Report

After a 5 year drought, I finally got to take the Vespa out for another spin on the salt! To recap what happened last time (2009), I ran with the KDX 200 conversion but due to lack of prep time I only had a "temporary" Vespa tuned exhaust with a power curve that peaked out at 82 mph. Sure enough, despite having my fingers crossed really really hard, the max speed achieved was 82.2 mph.

This year I did have a pipe tuned for the KDX 200 and I was also trying to fit a super charger however again ran out of time for that. So the scoot in effect was like I would have liked it to be in 2009 and I was hoping to get 100 mph+. I had done many dyno runs and CFD (Computational Fluid Dynamic) simulations which suggested 105 mph was possible. In '09 I had a screen to divert the air around my head and body, for '14 I had lowered and extended the seat so that I (6'2" and 100 Kg) could crouch down behind the headset. The simulations suggested I had room to move with aero but there was no way of going above 105mph due to the power curve of the tuned exhaust cutting off at that point.

The first run I did was Monday and the uncalibrated bike computer I had mounted told me I had done ~103mph!  I was ecstatic as not only did I hit what I thought it could do but it was so smooth. It literally felt like I was only going 60 mph. I went to get the official time but unfortunately my time was scrubbed as I failed to follow the rule of not exiting the track till after the 3 mile mark.

The next run was Tuesday and I gave it a bit more throttle. This time I did all the right things and rolled in with a ~107 mph indicated on the bike computer! Wow! That's the fastest Vespa in the world! This was too good to be true and I guessed the bike computer was out by a "bit". I went down to the van to get my time and yes it was out but by more than a BIT! 69 mph was my time!!!????!!!??  f*&k! !!??! Checking the bike computer it had somehow got a wheel circumference of 2 metres! No wonder it felt like 60 mph, because it was 60 mph!

I took it out on the GPS test track and sure enough could not get the scoot past 69 mph! Once in 4th it just stayed low down in the RPMs and did not accelerate further at all! Worse still I found trying to sit right back and behind the headset as I had hoped was impossible. Once a certain amount of weight went past the rear axle the steering behaved really weird. If I shift my weight one way the scooter went the opposite. I also had not bought the screen so I had no option but to work with what I had. Going over the scoot I managed to find the throttle slide not fully opening (the cable must have stretched over 5 years) and the front tyre had low pressure but everything else was in order. I changed to a slightly longer carb manifold to give me more low down power and hoped that would do.

Wednesday the track was moved as the salt was breaking up. In the afternoon I helped in the registration van (competitors are obliged to volunteer somewhere for a shift). That afternoon more than 50% of the runs were records as bikes and cars shot down the fresh track.

Thursday was my last chance, so I got out earlier and was about the 25th to run. The track change had also meant that a 1/4 mile timer was gone and times were therefore measured from  between the 2 and 3 mile markers, I had to maintain top speed for 1 whole mile! That is with no fuel pump just gravity feed! As I headed out, I also found the track very chopped up and it felt like driving down a beach that had been churned up by 4WD's. I positioned myself as low down as possible, wound her out in 3rd and once in 4th breathed a sigh of relief as she still kept accelerating.

I got her up to ~90 mph and tried to line it up in a flat spot between the tyre tracks. I had to do this speed for a full mile, not seize the engine and also try and go faster. I found a sweet spot and ran between two ruts, this worked well for 1/2 mile then the ruts crossed and I had no choice but to just go with the bumps.  By the end of the run my arms were aching from fighting the steering. Despite the hairy ride the scoot handled the run very well, not missing a beat and not blowing up!

The final time was 89.664 mph. Although this is not the 100 mph I was after, it was way better than the 69 mph I started with! It was also better than the 82 mph from 2009 so at least I am heading in the right direction!

In summary Speed Week 2014 was another real adventure, a challenge to get there and all the highs and lows of any other adventure sport. It gives you a harsh reality slap but then always leaves you with the impression that "next time" will be faster... that is why it is so addictive!

A special thanks Tiny, Bob, Graham and Ross for the support and the 374 team for the company and food! A HUGE thanks also to the DLRA for putting on such excellent event!

Paul McIntosh #647

Update: A postmortem of the Vespa on the dyno showed that I had lost 33% of the engine power, most likely through seals going bad from sitting doing nothing for years. Lesson learned is to dyno the scooter BEFORE not after to check it's health. Time for a rebuild which I should have done BEFORE!