TOPIC:

good morning folks.

so, I stop at a stoplight (as I guess you should) and my GPZ1100 backfires... this bike is new to me and I am still figuring everything out. but I was under the impression that backfiring was a result of a bad carbaurator setting..... this bike is an 83 with an efi. are the efi settings adjustable? or might I just have a dirty air filter?

Where are you located? I am in Atlanta.

I have an 82 GPz1100.

For a new bike, unless you have the service records, I suggest you go through all the periodic maintenance steps in the manual.

Out of four bikes I've purchased, two came with zero clearance on valves The GS1000 which only has 7600 miles on it since new
is barely in spec and the KZ1000A1 has a gnat hair (0.002-0.006). Lots of other stuff had been left undone too.
I'm catching up and fixing some damage done by the PO this weekend if my helicoils show up.

If you still have problems, there is a section in the manual on troubleshooting the EFI. It's pretty straight forward. I'll be going through mine because the PO reported backfire as the reason he started messing around. Will appreciate hearing what you find and I'll report back as well.

-Duck

Thanks Duck.
you seem to be the only one who wants to talk about the GPZ with me. I really need to get the manual begore I start to take things apart. I have been happy with clymers for my KZ1000. Is there a better for the GPZ?

I am in Daytona right now. I am not sure what happened to my signature?? it used to show up.

OK... I'll talk about your GPZ with you bwhahahaha

Seriously, carburetors may not be the cause of your backfiring or most backfiring. The most common causes of backfiring are:

1. weak spark
2. air leak in carburetors/intake
3. poorly sealing exhaust manifold gasket

A weak spark can cause backfiring due to incomplete mixture combustion. This usually occurs as pops through the carburetors while cruising down the road... An air leak around the carburetor area can cause backfiring. These tend to be a bit more explosive. Check any vacuum hoses for leaks, vacuum plugs and intake manifolds. Rubber tends to crack with age and where it is near heat. A crack allows cold air to focus on your piston crown and you can hole a piston. Last, if your pipes didn't crush the exhaust gaskets that sit in the cut-outs in the cylinder head, then you will get backfires simliar to the intake leak backfires.

Timing, valves and bad plug wires/caps can also cause backfiring.

Listen to WG, he's MUCH more experience than I.

My 82's throttle bodies, have a vacuum port between the butterfly and the head. WG's mentioned leak can occur here.
My hoses looked original and were cracked.

The exhaust gasket, in my experience, has caused popping in exhaust on deceleration when leaking. Have not seen backfire through carb as result of leaky exhaust, but I'm pretty new to this stuff so take that into consideration. Have not heard the GPz running yet

It's still a good idea to run througn the all the scheduled maintenance. At least check the stuff where they note "damage may occur". The factory manual is good. Mine is Kawasaki pn 99924-1026-03 but only covers the 1100's through 82. It's got 83 KZ1000-R2 but that's it for 83. Dealer should be able to order you a more recent manual. Or, you might find through one of the used book search engines.

I was actually looking for an 83 but this 82 turned up and for the $ I couldn't resist.

-Duck

Thanks George, I thought things were going to get easier.....
I like my 77 kz1000 because it had no vacuum system, points and carburators which some think are a hassell but I could understand as they were familiar... I am in new territory with EFI, electronic igntion, vacuum system etc.... gives me a whole new way to spend my evenings and more excuses for not mowing the lawn..

I am sure I will have many more questions as I go through this. Glad I have you guys !!

A couple more things you should check.

1) The o-ring behind the throttle position sensor (under a cover marked DFI on the right hand end of the throttle bodies) is prone to fail and leak gas into the TPS itself, ruining it. This can cause rough running, especially at idle and low rpm. If you remove the TPS to check it though, it should be reset using the factory tool. If you do not have access to one just set it to the highest idle, then adjust the idle screw.

2) The rubber ECU mounts should be checked. They get old and crack up. Do not let the ECU clatter around on broken mounts...it WILL kill it. Keep a spare key with you and if you get a DFI code on the tank/idiot lights use it to remove the seat (leaving the ignition on) and check the LED on the ECU for a diagnostic code. Don't turn the ignition off to lift the seat as this will clear any codes.

The EFI on these bikes is an excellent system way ahead of it's time. It's not adjustable, but neither is any modern EFI. It can be upgraded with a modern pump, adjustable fuel pressure regulator, injectors and PowerCommander though, just like a modern bike.

G'Day,

If you do get sick of the kawasaki EFI system, look at replacing the ECU with a megasquirt, it's fully programmable and will enable you to tweek it for your riding conditions.

Just my $0.02 worth

Sid

all very insightful stuff.
thanks guys.
I had a new one today....

came off of the hiway and all of my idiot lights were blinking. I think I must have some loose wiring. and who knows whatelse. I plan to dig in this weekend and see what we can find.

Thanks for all your help.

I know I'd never swap EFI for carbs, but if you become bent on 'retro' fuel management I think I have some BS series that will fit.
-Duck