Rockstar Energy Suzuki World MX1 has this week headed from 1600m above sea level at Guadalajara for the Grand Prix of Mexico to the beachside setting of Beto Carrero in Brazil and the set-up of the factory RM-Z450 has been adjusted significantly to cope with the change in conditions and the high temperatures. Here, Data logger and FI technician Roy Matheson explains a little of the demands on the motorcycles and the changes made to find optimum performance that saw Clement Desalle capture second position overall in Mexico; and Tanel Leok fifth.
Says Matheson: "In Mexico we were at 1600m and that meant there was less pressure in the air and therefore less oxygen for the engine to burn. With a fuel-injected bike, what happens is that the air-pressure sensor calculates to provide less fuel to the engine to have optimal burn. The bike runs exactly the same as it would at sea level, but of course there is less power. But we can compensate for that with higher compression ratios. We have some information from testing and races we have made in the past at these altitudes, but each scenario - especially when we come to a new location - is rarely the same.
"In the case of Mexico we already tried a few settings in Europe that we thought would be OK for this Grand Prix and then had some planned modifications in reserve. We then sent the riders into practice with our estimations and worked out the rest from their comments. We changed the bikes from the first session to the second.
"For Mexico, the fuel-injection setting was actually pretty close to where we wanted it to be so to make the changes was a five-minute job with the laptop. Other things like the engine setting and the compression ratio is a bigger job. The big advantage with fuel injection is that everything is calculated automatically whereas with a carburettor you need to already have it set up before you get there. It wasn't such a big job before with the jetting inside the carburettor and most manuals have a table of suggestions or a guide to use.
"The race in Brazil is next to the sea so we'll switch back to the settings we know well from Europe. The heat doesn't affect the bike too much and they can normally run cool enough to fall within the performance parameters. A bike that's too hot will lose power but our cooling system is good enough to cope with these temperatures.
"These flyaway events are a challenge because you prepare and you pack what you think you will need, but of course there is no back up. We are a bit limited with the weight whereas in Europe we take everything to the GPs because we have the space in the truck and weight isn't an issue."