Getting Started

Hello All,
I'm new to KZrider.com and looking forward to all this forum may offer. I recently bought a 79 KZ750 twin with less than 10,000 miles on it. I really love it. Just put a rebuilt starter on it and a starter clutch (which it didn't need) and I'm having a hell of a time getting it started. My bike didn't come with a owners manual so I'm not sure what I'm doing wrong. It cranks and I got it to fire for about 3 seconds yesterday. I'm not sure if I'm over-choking it or what. I had the battery check at O'reillys and they said it was good, but I only get a dozen cranks out of it before I have to charge it again. That should be enough to stat it I would think. Anyone have some pearls of wisdom for this "newbie"? Thanks.

1.Clean and tight battery connections.

2.Check the Negative(-) battery cable to the engine mounting bolt for tightness.

3.Properly gapped sparkplugs at the correct heat range(I'm guessing NGK B8ES or Denso W24ESU at .028" to .032").

4.If ignition points are in the engine,check them for worn parts/excessive gap.

5.Fresh gasoline in the tank.

6.Check/replace the sparkplug caps(they screw onto the sparkplug wires)as they fail over time.

This website might help too: www.kz750twins.com

The gas in it probably dried into varnish and plugged the carbs up.

At minimum:

1) change the spark plugs.

2) take off the fuel tank, dump ALL gas out of it and rinse with clean gas. Take the sediment cup off the petcock and clean it and the screen.

3) take the bowls off the carbs and spray clean them out and spray the floats and carb guts lightly.

Ah the twins... so easy to work with.

Everything already said, +

All you need is fuel+air (at a proper ratio), spark, and compression.

1st - GET A MANUAL, your really going to need it to do the valves, which IS regular maintenence on these bikes.

If you dont have a compression tester... pull both plugs and put your finger over the hole, 1 at a time.
Crank the engine and it should have enough compression to float/force your finger off the hole. That is usually enough to start the bike.

Plug the spark plugs into thier wires, and tape them to the cylinder head.
Crank the engine and look at both plugs. They should have blue, snapping sparks.

Button everything back up, and attempt to start the bike.
Crank it for at least 5 whole seconds at a time. You don't need to open the throttle at all and shouldn't.

If it doesnt start - pull plugs again. Are they bone dry/new looking? - not enough fuel.
Are they wet/smelling of gas? - not enough air.

You will likely have to pull the carbs off the bike, and give them a thorough going thru/cleaning.

Clean them out (AFTER REMOVING ALL RUBBER BITS) 1 at a time, with spray carb cleaner and a single bristle form a steel brush (push it thru all jets). You can use a sharp knife to taper the end of the carb cleaner straw, and stick it into the jet ends. Then shoot cleaner thru and watch for it to come out passageways in the carb throat. Both carbs should flow the same.

When you put everything back together, it must all be AIR TIGHT! from tip of airbox to tip of exhaust!

Anyways... let us know how it goes...

Good luck!

Hey everyone. Thanks for the great tips. I actually got it running the same night. Turns out I was choking the crap out of it. It runs pretty good, a little lean I think. Time to tinker. Thanks again for the help.

Sparkplug "Readings" are usually taken at the center insulator.

WHITE,can be dangerous if ran long enough,can lead to overheating/melting of pistons/burning valves.

BLACK,far too rich,could be due to clogged air filter/high carb float levels or low spark energy.Also ignition coil(s) failing due to heat.Sparkplug caps can give this indication if they are failing.

LIGHT TAN,just about right for efficient combustion.

ratdog54 wrote:

Hey everyone. Thanks for the great tips. I actually got it running the same night. Turns out I was choking the crap out of it. It runs pretty good, a little lean I think. Time to tinker. Thanks again for the help.

Good work man.

While riding it, pull the choke a little. If the performance improves than you've thought correctly, and it is indeed lean.
If the performance drops off and the bike becomes slugish, then your ok.
If the bike starts to sputter hard and blaps afterfire out the exhaust, then you were too rich to begin with.

Good luck!