Hi, Recently got a 96 748 biposto and love it. Only, the gearing seems to be really low! Its got a 14t front and 36 Rear. Which i believe isnt far off standard. But the bike is at 11000 RPM in 6th touching 120mph. The clutch definitely is not slipping either. Could someone have played with the gearbox previously?? as im totally confused! Thanks
I think the standard sprocket size on the 748 is 14/38 if you have a 36 on the rear that a bit high and should give a higher top speed although the bike probably couldn't pull that top end anyway. Is the bike still pulling at 120 mph as the rev counters can be adjusted and may be out. Steve Try giving it some in a lower gear and see if the limiter cuts in, it should be around 11,500 revs , it might give you an indication of your rev counter accuracy.
Will, standard gearing is 14 - 38, many run larger rear sprockets like 40 or 41 to get better drivability in town but lose top end. Check here http://www.gearingcommander.com/ for the speeds/revs/gears relationship. Your 14-36 sprockets would give you 164mph at 11k in 6th if the engine could pull it (it won't in standard form) I think you may have a problem with your rev counter
Thank you for the speedy replies. Took the bike out again and yes the Rev counter is massively out of sync. Went to at least an indicated 15000 and no redline. Not used to v twins at all as I thought it sounded right! What is the process to calibrate it?
Will, sometimes a bad earth from the headstock area into the main loom can create odd behaviour of the clocks. Most often it is a broken wire or burnt pin within the front to main loom connector. The connector is under front RHS of the fuel tank (the big round one) and earth wires are black, there are a couple of wires that run through that plug which earth the clocks, indicators, idiot lights. When one breaks or a pin in the plug burns out due to poor contact/high resistance you get all manner of different and spurious faults on the dash cluster depending on which path/resistance the earth takes.
As dentil says an earthing problem can cause erratic behavior, but it could also just need adjusting which can be done through a small hole in the back of the clock.
That looks useful. Also, a good baseline starting point might be to assume that the engine is idling at about the right speed and calibrate the rev counter accordingly.
