KZ750 twin.....Soo slow.

Well,just picked up a new to me kz750 twin.Didnt run when I brought it home,but I went through the carbs and cleaned them good and also soldered a hole in a float(money is tight) :laugh: Adjusted the points as per the manual,cleaned plugs,checked spark,and compression checked her (150psi).

Now she starts right up and purrs...I do get a little popping from the exhaust when warm.
-Has a two to one exhaust
-no filters
-have also run it at every possible timing mark on the adjuster..

The guy I got it from swears it used to be fast...But this thing is god awful slow..Hardly enough power to pull me out from a start,but runs ok when moving.I cant imagine it would do more than 40mph though..

Where do I start?I have been searching the forums for 3 days,and I cant seem to figure it out.
:lol:
Thanks in advance,and sorry for the long post.

Welcome, Mr. Boosted!

Make sure you get a manual if you don't have one, and go over every possible adjustment. Check the floats, the timing, the carb balance, the coil, etc etc etc....

Let me assure you, that although they are not a Ninja, it does get out of its own way just fine.

:lol:

Welcome to the club,,, . It sounds like a timing advance issue, I would remove the timing cover and watch the timing advancer as you are slowly opening the throttle. Some guys say to use a timing light but it isn't necessary, using a bright flashlight you will see the weights swing out gradually till you get to around 3 or 4 grand on the rpm. Then slowly close the throttle and you can see them swing back. If you aren't moving they need cleaning and a good light lubing with never sieze. Messy stuff the never sieze but it lasts just about forever.
You will have to remove the points or pickups, which ever you bike has and remove the advancer so you can clean and lube the pivot pins and clean and lube the shaft that it rotates on.
good luck.

Maybe it's only running on one cylinder?
I know the 750 twin will start, idle, and run, on one cylinder, I rode one that way just to see if it could. But it sure didn't have any power.

Well...both pipes are hot..but it is a two-one.

....the advancer is rusty,but moves freely,i will clean it anyway.

Also setting the timing with the light like the manual suggests maxxes out the three screws.It is turned all of the way clockwise,and still looks to need a touch more?

And the points are set correctly,i think? .35 correct?hard to know for sure... :dry:

Is that mm? I know its .014 - .018 in inches. I ran my twin on one cylinder (limp home) and it got to around 40. I wouldn't want to drive it for to long like that though. With both going hard I got it to 105 before I decided not to push any harder. they aren't stupid fast or anything but they pull pretty nice from the bottom end.

Well...rebuilt the advance mechanism,and now she wont run


Its nice and free now...i dont know.

superboosted wrote:

Well,just picked up a new to me kz750 twin.Didnt run when I brought it home,but I went through the carbs and cleaned them good and also soldered a hole in a float(money is tight) :laugh: Adjusted the points as per the manual,cleaned plugs,checked spark,and compression checked her (150psi).

Now she starts right up and purrs...I do get a little popping from the exhaust when warm.
-Has a two to one exhaust
-no filters
-have also run it at every possible timing mark on the adjuster..

The guy I got it from swears it used to be fast.

If you mean it has no air filters, it will never run right.

You probably put the points cam back on the shaft 180 degrees out, been there, done that

I don't know how well a 750 twin will run without filters, never done it. I don't run "any" motor without filters.

superboosted wrote:

Well...rebuilt the advance mechanism,and now she wont run


Its nice and free now...i dont know.

Those can go back on the crankshaft 180 degrees out and it won't run at all that way.

Guess how I know that....funny how something with a 50% chance of going on wrong will go on wrong 100% of the time.

superboosted wrote:

Well...both pipes are hot..but it is a two-one.

....the advancer is rusty,but moves freely,i will clean it anyway.

Also setting the timing with the light like the manual suggests maxxes out the three screws.It is turned all of the way clockwise,and still looks to need a touch more?

And the points are set correctly,i think? .35 correct?hard to know for sure... :dry:

Point gap on the twins is .012" - .016", .014" nominal.

superboosted wrote:

Well...rebuilt the advance mechanism,and now she wont run Its nice and free now...i dont know.

Would remove plugs and visually check for spark.

Then gap and clean points.

When again running, would use strobe-type timing light to set ignition timing.

With engine at idle rpm, would spray water mist onto exhaust headers and verify cylinder combustion in both chambers. Water should sizzle and instantly vaporize. If not and water just runs down the pipe, cylinder is not combusting.

Popping may lessen with an air filter in place.

Good Luck!