KZ 1100 backfires and sputters

So my KZ 1100 1981 is backfiring from the exhaust + carbs and sputters when cold. When warmed up runs great. Cabs were cleaned, synched, boots seem to be in good shape (sprayed starter fluid oround and nothing happened.
Seems like an air leak-but as far as i checked there is none...What could be the problem?
Thanks!!

trojan wrote: So my KZ 1100 1981 is backfiring from the exhaust + carbs and sputters when cold. When warmed up runs great. Cabs were cleaned, synched, boots seem to be in good shape (sprayed starter fluid oround and nothing happened.
Seems like an air leak-but as far as i checked there is none...What could be the problem?
Thanks!!

Backfires through the carbs when cold, but not when warm?

Good Fortune!

Jup, just when cold-when the chocke is still on. I can hear popping or actually more of a puff-ing noise and sometimes even see gases being pushed through carburetor manifold.

It sounds like you may not have properly tested for carb holder leaks. What was the idle set at when you tested? It is very important to temporarily set the idle as low as possible when testing - should be down well below 900 rpm as far as possible without stalling engine. This results in the slides being closed which in turn raises the vacuum level within the carb holders. Then spray carb cleaner around the mating surfaces between the carb holders and cylinder head and where the carbs join the holders. If there is a leak it should affect the idle and may stall the engine. Also check the little vacuum caps on the carb holders to make sure they're in good shape and tight. Give it a try - it's easy to do and may show a leak. Ed

It was the boots!! Did as you said and tne engine stalled. Also found out that carb cleaner is way better for testing because start spray evaporates too quickly.
Thanks for the advice!!

I'm glad it helped! Ed

A word of advice on removing the old carb holders – The original carb holder screws can be extremely hard to remove from the cylinder head. Lots of folks have stripped the screw heads or broken the screws off in the cylinder head trying to remove them – they can be VERY stubborn! I had read about this problem before replacing my carb holders and decided not to take chances. I soaked the carb holder screws with Kano Kroil for 3 days before removing them and I used screwdriver bits I had modified to match the JIS screws. You may not be aware that the crosshead screws on the Kawasaki bikes are not Phillips even though they look like them. They are made to the Japanese Industrial Standard (JIS) and do not match up well at all with Phillips screwdrivers. They actually work MUCH better than Phillips screws because they are not designed to “cam out” so you can apply more pressure without stripping the heads, but you MUST use JIS bits or bits modified to fit the JIS screws or they will strip.

Having soaked mine for 3 days with Kroil and using a JIS type bit my carb holder screws came out very easily.

Kroil can be ordered directly from the manufacturer or can often be found at gun shows or some gun shops. I ordered mine online. This is what I use as shown on their order form: Kroil 1/2 pint (8 oz.) can - $9.25 ea. Here’s their link:

www.kanolabs.com/penLub.html

Regarding the JIS screwdriver bits – if you haven’t seen the thread below you may want to take a look at it as it describes how to modify Phillips bits to match JIS screws – it’s very easy to do and well worth the effort.

kzrider.com/forum/21-tools/532335-budget...ewdriver-tips#532335

Here’s what the Kroil can looks like. A half pint can will last forever; no need to buy a larger size. Ed

Yes, I've just pulled them apart and had one of the carb holder screw head stripped...
(Had to file the head with metal saw and wedge a large flat head to get it off.)

I've replaced them all with black Allen (Hex) 6M x 16mm, and placed washers to pad the screws a little. Length of screw should be between 14mm and 16mm as far as I can tell.

Love the Allen screws. I'm trying to replace all engine screws to Allen as I go on. Not very authentic but mechanically awesome!

Cheers

Just be careful not to overtighten the Allens and strip the threads in the aluminum engine. Ed

I used anticease on mine, hopefully it makes it easier for the next time.

mopguy wrote: I used anticease on mine, hopefully it makes it easier for the next time.

They recommend using blue lock tight on these in the manual. Plugs, valve cover bolts, side cover allens etc love anti sieze but not on these.

KZB2 650 wrote:
They recommend using blue lock tight on these in the manual. Plugs, valve cover bolts, side cover allens etc love anti sieze but not on these.

What - are you kidding??? The Kawasaki Service Manuals I have are VERY SPECIFIC about which fasteners get a locking agent (loctite) and those manuals DO NOT recommend using locktight of any type on any of the fasteners you listed - DON'T DO IT! That is really bad advice!

What manual do you have that recommends using locktight on any of those fasteners??? Please show me the text. Ed