MV F4 Base Runs - Written 10/04, Update 01/10 added SPR runs
Somewhat surprisingly, I’ve never had anyone come in and ask me to do anything to an MV F4. Not sure why, but there you go. Accordingly, I’d never dyno’d one. So, when I got the chance recently I took a trade in down for a few runs. I also took the opportunity to compare it to a couple of others.
All these bikes are running std mufflers and chips. I did fit one of Doug Lofgren’s WCT chips to our trade in to try, so that run is shown also. The bikes are just set up as we normally do.
Green is the trade in all std. It had about 20,000km on it at this point and had spent some time at the track, so was well run in. The red curve is the same bike with the WCT chip fitted. The midrange improvement shows the biggest benefit of this chip better fuelling at lower RPM making it a nicer bike to ride. You can see the low end improvement the WCT chip gives more clearly in the torque graph.
Dynograph courtesy of DYNOBIKE (03) 9553 0018
The torque curve shows why they feel (like most powerful 4 cylinder 750’s) like they really come on about 9,000 RPM. They’re quite good fun to ride when you get to rev them, and I imagine they’d make a very nice track bike, wailing to 13,000 RPM with glee
Now we’ll add a couple of others, just to show some variation. The blue curve is another bike, particularly strong at the top end but somewhat lacking in the middle. Not sure what state of tune it was in. The yellow curve is a press bike, which was probably fairly new at the time
Update: The SPR
The SPR engine varies from the base model engine in a few areas cams predominantly, head, pistons, gear box (close ratio) and eprom to suit. This engine is also used in the last of the F4 750, badged the F4 750SR. I developed an eprom for an SPR a few years ago with the RG3 mufflers and a BMC air filter, and did some dyno runs. Compared to the base model engine it’s a dog in the middle, quite a bit more powerful, and a real joy to use when you get to rev it. For a 750 it’s a very powerful motor, so the doggy midrange is no surprise. And like all MV engines it sounds wonderful, especially as it wails toward the rev limiter.
The following graphs show the SPR compared to the F4 from the first graphs. Power then torque. The different in character is clear.