Spitting noises - blow back

I got my 80 KZ650 E1 running again, but i'm having some issues with the carbs still. When i'm riding i get this spitting sound coming from my carbs. it sounds like i'm popping popcorn or something when i'm accelerating or deccelerating. i think it's blowing gas back but i can't figure out from where. what would cause this?

it's also dragging ass when you try to really open up the throttle.

i'm sure i'll have to take the carbs back off to do something, but what should i be looking for?

Get a couple cans of carb cleaner and spray all the little passages, pull the jets and make sure everything is clean. There are not many parts in there just make sure every thing is clean. Also clean the tank and replace the fuel filter or you will suck trash into your clean carbs and have to pull them again.

I'm all for it.

What's causing this though? Is it an air problem or a fuel problem?

Spark plugs misfiring?

Have you checked your compression? It may be a tight intake valve, or you could have a worn exhaust cam lobe. Do a compression test and clean the carbs as suggested with a sync as well. Make sure of no vacuum leaks. Its also possible that your Ignition is letting you down, check your plugs while you got them out, make sure you've got excellent spark.

Sounds like the carbs to me. Points will do this to when the adjustment goes away. These bikes are old and trash gets in the tank and goes straight for the carbs. Have you taken the carbs off and cleaned them?

Make sure that everything from air filter to exhaust end is completely air tight!

Generally, if your putting a demand on the bike (accellerating) and it bogs down, its too rich. If you have hesitation/erratic at idle, its lean. Not always, but most times...

Swap your Main Jets out for a smaller/leaner set, and see what happens. If it improves, then go leaner again. When it stops improving with a change, go back to the previous jets. Same thing for going larger jets.'

Jet it correctly. Set your mixture screws with an accurate tach or vacuum guage. Balance your carbs.

GL!

How do i know if there's a vacuum leak?
All my intake and air box boots look good. My bike didn't have the stock air emission cleaner so i just capped off the inlets on the valve cover and carbs.

I've pulled and cleaned the carbs at least 3 times in the past year. new accelerator pump kit, new gaskets, new float needle. I don't have leakage anywhere when shes running or not.

I do need to synch the carbs still. i did the bench synch with the wire by the book. i don't have a vacuum guage or a fuel level guage for the float height though. i just saw the homeade version of the vacuum synch though. pretty awesome. where can i get one of those float height levels that's not like $60. I searched on ebay but didn't find one. i'm sure my float heights are off. i can't get an accurate reading with the clear tube method. it's incredibly frustrating when you don't have a proper work space. (mine's my driveway and out of the back of my van for now)

Here's how to check carb holders for vacuum leaks: Idle the bike down to the lowest RPM it will idle at; while idling - spray carb cleaner around carb holders where they mate with the cylinder head. If the bike stalls or the idle changes noticably the carb holders are not sealing properly with the cylinder head. If this is the case, replace the carb holders. They can look perfect on the outside but still have tiny cracks on the mating surface between the carb and head that allow air to be sucked in at idle. These cracks can really effect idle but generally don't effect running much when the throttle is open because the open throttle lets much more air in through the carb and less vacuum on the carb holders. Ed

Tool

Gorham wrote:

i'm sure my float heights are off. i can't get an accurate reading with the clear tube method. it's incredibly frustrating when you don't have a proper work space. (mine's my driveway and out of the back of my van for now)

Take some carb holders and mount them on a piece of wood and level them (the ones in the pic are level its me using the camera thats out of level)
I use a chalk bottle for carpenters chalk to fill the bowls with gas. Then I use the clear tube to drain it back into the bottle. Its a tedious job sometimes but it has to be done. The clear tube is on the 2nd carb.

So i'm adjusting my timing, and i can't get my ohm meter (digital multimeter) to fluctuate when adjusting the points plate on the backing plate like it says in the manual. Is there a trick to this?
I tried adjusting the backing plate to get more movement but I still can't get any fluctuation on the meter.

I still have to get the timing right with the light, but that's the next step... I'd like to get the one before it done right first.

My carbs are clean as a whistle. I think this is a major problem with this blow-back.

if you are setting points with a meter get a cheap analog meter and watch for the needle deflection. a digital isn't precise enough to be able to watch for fluctuations. i use an analog for setting points and for checking switches for the same reasons.