Topic: top out conundrum

[KRONUS0100]

how much does weight affect top speed of a given bike? 1976 cb750f with full vetter windjammer and krauser hardbags? i weigh 285 pound to boot. bike is topping out 75mph with factory spec carbs and 4 into 1 kerker
running 14 and 41 sprockets 630 chain...............16 inch rear rim........factory 82 kz750 gear ratio. at 75mph im only hitting maybe 5500 on tach.this f3 motor is supposed to have 9 grand redline. ignition timing is dead on for a dyna s-1.

any ideas?

[Powderman]

Weight should matter very little on top speed but more on acceleration. Some bikes just don't have the aerodynamics to pull red line in top gear. Can you not top 75 in any gear?

[Duke McDukiedook]

Something sounds amiss, I am a few pounds lighter than you and on a fairingless 750K3 can hit 90-110 without breaking a sweat.
When I was having crab problems I was having the same problems. Another thorough cleaning of ze crabs woke that dead cylinder up and had me tonning out.

Check your headers after a decent ride to see if they are the same temp.

[KRONUS0100]

my bad on gearing..............14 front and 32 rear sprocket.................stock for 82 kz750....................also stock front for 78 cb750f with 630 chain.
dont know what she tops out at gooing thru the gears, too busy watching tach and the road.  gonna pull carbs tonite or in morning and double check needle settings.......book doesnt say which direction from middle, just sez 4th notch.
thinkin im a wee bit rich,plugs are on dark side of normal, i wanna try the choke at point where she hits the wall to see if it gets better or worse before i pull carbs.

[madmtnmotors]

my bad on gearing..............14 front and 32 rear sprocket.................stock for 82 kz750....................also stock front for 78 cb750f with 630 chain.

Where did you get this information? All of the information I can find puts the stock 78' CB750F with a 14 tooth front and 43 tooth rear. 

MUCH lower gearing...

[LesterPiglet]

It won't have the power to pull with messed up gearing in combination with a 16" wheel and windjammer. As evidenced by your 5500rpm limit.

[KRONUS0100]

its kawasaki gearing for 16 inch rear wheel, not 18 inch rear wheel.  cant use stock gearing  or it will rev too high on the hiway.
anyhow, back from plug chop ride.  choke made no difference, and plugs are only slightly darker than normal.....but carbs are off bike cuz number 2 not flowing fuel again at idle.....pipe cooled off way too fast compared to others at idle...........nifty lil infrared thermometer....gonna go ahead and check needle jet clip position while im in there.
dropped plug and broke it during plug chop, good thing had spare plugs on bike, now gota go get replacement spare
still not making anysense as to why it feels like its hitting a wall long before it should........................................almost 6 grand shift points, felt as tho there wasnt anymore go at shifts, so something aint right

[madmtnmotors]

32 teeth rear is way to small, even for a 16" wheel. You've only reduced the wheel circumference by 5% 11%, but you've increased the gearing by 25%...