I got a 77 kz650 but it wont go faster then 85

My bike wont go past 85 mph an sucks down gas like its a truck please help or ill have to sell

must not be stock............

Willy1803 wrote: My bike wont go past 85 mph an sucks down gas like its a truck please help or ill have to sell

If not already done, would first check the crankcase oil for gasoline contamination by sniff-testing and examining its physical condition.

Would also assure that the timing is correct and that the automatic advance unit is properly functioning.

Engine might be running on just three cylinders, or maybe on just 2 cylinders.
Has the water mist spray test been performed?
Could use a common household hand-held sprayer to spray water-mist onto the exhaust header pipes shortly after starting a cold engine to assure combustion in all cylinders. Water spray should sizzle off every header pipe and instantly vaporize.

Good Fortune!

You need to clean the carbs. I had a similar problem with mine many years ago when it sat unused for a year with fuel in the carbs. My bike would start up easily but would not run faster than about 60 mph. I cleaned the carbs and the problem was gone. Ed

If stock air box, assure intake isn't obstructed by a rag or something underneath the seat.

If pods, assure filters are clean and clear and unobstructed.

Assure enrichener lever is OFF (choke lever is pushed down), and that the choke plungers are actually in the down position.

Assure that fuel levels are within spec, and not too high (clear tube test).

Assure muffler is not clogged.

Good Fortune!

or sell it to us cheap :woohoo: :woohoo: :woohoo: :woohoo:

sorry kidding..i bet if you follow the advise given youll be supprised with its power

More things to check --

Points in good condition and gaps set per specs.
Weak contact breaker spring.
Main jet not too large.
Incorrect valve clearances -- when were valve clearances last checked?
Is the throttle fully opening (all slides going to the top)?
Brakes dragging?
Clutch slipping?

Good Fortune!

Willy1803 wrote: My bike wont go past 85 mph an sucks down gas like its a truck please help or ill have to sell

Hopefully not a mechanically-challenged novice that just acquired his first motorcycle :ohmy:, in which event, much of the advice will likely be incomprehensible.

Good Fortune!

Yes ......go on.....

It is very likely that you have a motorcycle that is in need of basic, routine maintenance.
Get a genuine Kawasaki Factory Service manual for the specific year and model you have. They come up on eBay pretty often, and some are available digitally. Members here may be able to help. A Clymer manual is better than nothing, but the factory manual is more thorough.
You will need a few special tools, like some metric wrenches, metric feeler guages, and a set of JIS screwdrivers. A good carburetor synchronizing tool will also be needed. Morgan makes a good, though pricey one. Oh, and a pair of high quality torque wrenches. One in inch-pounds, the other in foot-pounds.
Carefully perform all the maintenance and tune up procedures in the order listed in the manual, and you will eliminate a bunch of problems and potential problems.

Back in the 1970s and '80s, Kawasaki never imagined what crappy fuel we would have today, nor did they assume that their products would sit around unused for decades, so the advice given above about crappy fuel clogging the carbs and rusted timing advancers will not be covered in the FSM, but is really good advice. Once you get it all sorted out, a high quality inline fuel filter can prevent a lot of grief.
This may seem a bit intimidating, but I bet you will be pleasantly surprised by the results. When properly cared for, the 650 is a real gem.

It sounds like it's running too rich and so won't rev out. In addition to other suggestions make sure the carb enrichment circuit is not leaking fuel through when the "choke" lever is closed.

Otherwise it's basic tune up, valve clearances, timing, spark plugs and a thorough carb cleaning. A good running KZ650 is still a pretty fast bike, mine still amazes me with it's performance, so 85mph should be easily met and exceeded depending on your bravery,

Of course the OP may have forgotten to shift......... :silly: :blink: :pinch: