Laverda fitted a Weber Marelli EFI unit to the 668. The control unit is situated under the rear seat hump and can be accessed by removing the tool tray from under the rear passenger seat. To open the box you may need to remove the whole rear seat unit (one of the cover screws is pretty much impossible to remove otherwise).
As standard, the chip fitted to the unit seems to be engineered to have a flat spot at around 4,000 rpm. This is presumably to pass emission and noise testing for some markets. Coupled with the original exhaust 'constriction box' and high overall gearing they conspire to make the stock 668 far from rideable around town or at low revs. I'd recommend fitting the Laverda upgrade EPROM chip, or maybe consider the chip from Fuel Injected Motorcycles (FIM) in Australia. Their opinion, though, is that it is hard to improve on the standard Laverda upgrade part.
As Duane from FIM said in an e-mail to me some time ago, "I regret that we do not have an UltiMap EPROM for the Laverda 650/ 668 series, as we have been unable to produce a significant benefit in the bikes we have tested. At present we do not anticipate making further tests. If you have access to one of our Hand Terminals or a dealer with one, you can use our DTM Megazone EPROM, which is an adjustable version of the original factory mapping, to make corrections which may improve the performance of your specific bike."
In essence, the later Laverda chip is probably the best you can get at this stage, and you might just be able to squeeze some more out of the engine with the FIM remappable chip, if you spend time and money on a dyno and have the right test equipment, but for most users, don't bother!
Laverda released an upgraded EPROM for the 668 which should be fitted to bikes that have the upgraded X-piece. This eliminated the earlier flat spot, and improved low speed running. It isn't clear if this mapping would be OK fitted to a bike with non-modified exhaust system, but I can't really see why not, just be sure the bike is retuned to the new chip.
It is interesting to note that the rev limiter in this latest EPROM for the 668 would appear to be set to a lower value (8500-8700 rpm) than that for the original 668, which was set at something closer to 9000-9200 rpm. The newer chip is identified as M929_85 and has checksum EDA3, Laverda part number 077003000022, This change in the rev limiter may be due to perceived problems with the balance shaft failing at sustained high revs. There is also a note in the parts manual that the newer chip is 'not for the 668 model' or some such, but it certainly works well and was supplied by my bike with the X-piece.
Another hint - the engine comes tuned very lean, with a low CO emission content. The factory workshop manual suggests altering this 'for performance applications only' up to around 6% or so. This might get you in danger from Greens or vehicle pollution testing equipment, but does result in better performance and a cooler running motor.
© Steve Carr, 2001-2007
Site created February, 2000. Last modified Friday, May 15, 2009
30 May 2005