NOW , Compression Ratio isnt Everything , though its Close . Volumetric Efficancy , in the manner of cylinder filling , counts for a bit . OR a good Deal .
Note the little 2 strokes with , when the C.R. is defined by the port opening , is naff all . Hence . If thetd banned ' tuned pipes ' in F - 750 they wouldve been slugged .
Youngh UPHILLS Bonneville would be generally regarded as the Quickest , But then theres
. . . Shareing the same final drive ratio . but with the advantage of the
Simplex Chain ( less Drag ) slightly higher .Overall .Not Only That . 9.5:1 pistons with the Flatter Crown giveing enhanced flame propagation , Combined with the 1961
8 - stud Head with the reinforced chambers , somewhat larger Valves , the most advancd porting , according to theory , available in 1977 / 78 , with more evolved
seating aragements ( the Valves , Idiot . Though the seat wasnt bad ) than were commonly available for more than a decade afterward . Best Bonne Head on the planet ?
60 Bucks , Mate ( for the work ) Theyre Not Bad Standard . ( if somebody hasnt been at them ) . COMBINED with tuned length Exhaust pipes , trimmed to fit close for cornering clearance . The Mega's perforated baffles would be igniteing chamber purgeing remenants from 93 / 94 mph . In Third .
110 in third equates to 131 or 135 valve floating , if a decline onto flat in top . Quite ammuseing out accelerateing a Z1 in 2nd , uphill . Then , standards slipped as the years passed .
Later sold to a ' Farm Boy ' , run flat continueously for 6 or twelve months , the left pipe flattened to half width , untuned . We ran it in a 1/4 mile car club sprint .
Took a few runs to get a clean one , juggling clutch slip ( worn ) bogging ( knackered ) and change ponts ( the old girl'd go flat at 90 in third .Had to shift to top for line .
Pulled down a few weekends later , a 20 thou feeler guage went between sleeve & pisto , one comp ring was in twenty pieces , one sixteen , with some missing , I think one whole and one halved . :shock: This was from 35.ooo on the overhaul , includeing Farmer Browns Tenure . Really WFO isnt good for the rigs , the throttle needs rolling on , to a degree . Mains were shot , bigends wernt bad but needed first undersize .
We got a 14 . 5 . Id estimate we lost a half a second off the line , half easy at the end , and another half in the middle , plus annother for overall uselessnes .
So just the one and a half is 13 even . seeing it'd snot anything , id take 12.5 as sanre .Particularly as Stock 750s tested in Aus ran 12.5 . Another Quaterd be gained at the strip from the burn out trough .
If that didnt work , at .060 after the rebore , and with Duplex primary gearing , it mightve held it down under 130 , but itdve got there quicker .
If sailed past the Z1 in 2 nd ( or away from , to be concise ) after edgeing it in first . a year or so before . ( we'll get index plunger spring lectures next )
Now , this nasty contrivance .
23T for starters should throw it out . However , New MkII 32 mm Amals , and all as as good as , New . But settled in , etc ( First build @ 7.000 Miles . So , the Bores Were Straight .) You can see its Also Pre Unit , also Duplex Cradle . The similarities in chassis dynamics arnt far differant . The Commando a bit stiffer and sharper in the front , The Bonneville in the rear , both steadyer or less nervous two up ( a Pillion ) Commando more of a pig to get off the line . But it held a XS 1100 Dead even ( on two runs . A wheel Ea way on the start , nothing in it from there , XS had 4-1 Ex , C'do Std Cam put in tby the ,much easier of the line , pull from clutch home , but not the mid upper punch of the two S .
Send me Youre Commandos .
' We ' need to prove this Point . ! 8) :shock: