1980 Z1 Classic Carb Conversion

I recently found and helped my brother buy a 1980 Z1 Classic from the original owner. Cylinders #2 & 3 are running lean. I'm thinking the end game is to put carbs on the beast. 7,400 miles, always garage. It's only serious flaw is the fact someone stole the tank off of the bike and it was replaced with the standard LTD tank. (modified to work with the fuel injection)
Has anyone documented a carb swap for the EFI on one of these?

Why do you want to do a carb swap. The Z1 Classic is a very rar model and the last one i saw on ebay was sell for 6500 Dollar
with carbs.
The only reason to do a carb swap is,when the ECU dies. This can happen when you try to start the engine with a weak battery.
This will shot the ECU internal voltage regulator and some important components dies with him.
A good cleaning of the injectors and maintenance of the injection system will solve your problem.

+1 on cleaning the injectors.

On a stock engine, the fi works well personally, I would try to get it working before considering a conversion.

The carb conversion is pretty straight forward, but will require some time getting it properly tuned, and can be pretty expensive.

Thank you for the input Gents. Scirocco, I understand cleaning the injectors, I suspect any quality automotive shop can do that for me. What do you mean by "maintenance of the injection system?"

Are there modern injectors that represent a high quality swap?

Try searching the archived discussion threads here. I remember reading a couple of them, though they were about the GPz system. I bet the two systems are nearly identical.
I seem to remember that most of the parts can be replaced with newer parts, the ECU being the most important exception.

Will do. TexasKZ. The PO said he had the injectors cleaned. I don't know exactly what that means or if it was a reputable shop. Onward through the fog.

Can you upload pics of the spark plugs.
A lean condition on #2 and 3 could be a leak on the intake boots.
A bad Injectors have the characteristic to leaking drops of fuel under fuel pressure that could be the opposite of lean = fat .

TexasKZ wrote: I remember reading a couple of them, though they were about the GPz system. I bet the two systems are nearly identical.

I may not be remembering correctly, but I believe the EFI system from the '80 and '81 bikes is different from the '82 to '85 bikes.

The early bikes (80 classic, 81 GPZ1100) have fuel injectors that mount directly to the head. The later bikes have fuel injectors that mount to the throttle bodies.

The early bikes use a barn door type air flow sensor. I'm not sure what the later bikes use. Maybe MAP? But they don't use the door sensor.

My guess, having never ridden either one, is that the later system works a bit better. 1980 was pretty early for EFI. And those barn door type airflow sensors had issues.

Wikipedia agrees with my memory: en.wikipedia.org/wiki/Kawasaki_GPZ1100_B...uel_injection_system

It also mentions that the throttle position sensor is very primitive on the early bikes.

But I agree that it's definitely worth it to try to fix the EFI before completely reengineering the bike.

One trick with converting to carbs is that you'd need to plug the unused fuel injector mounting holes that are cast into the head. Just one more detail to consider.

No eBay APP ID and/or Cert ID defined in Kunena configurationDOHC is right,the early EFI systems have a air flow meter and the injectors in the cylinder head







EUR 49,99 !!!!

I'll can confirm the injector in head as shown in Scirocco's pics. Pic #2 cracks me up "Electronic Fuel Injection was always a good idea. Making it work was an even better one". A bit of irony there. The bike isn't in my garage yet. I'm wrapping up another project within the next week. So I can't pull plugs at this time. Originally I was planning on converting to carbs but you all have inspired me to battle with the FI.

A carb swap can do every , (sorry for that), idiot with two left hands.
A classic unique and rare bike like your Z1 classic should be technical in the same condition as they were sold in the past.

After fighting the DFi on my 81 gpz1100 for months and many $$$, I said screw it. Sold the parts off and bought a set of Mikuni RS flat slide 34 mm. Fit right on and fired right up. Best move I did on my bike....should have done it sooner. I say convert, but keep the parts so it can be converted back if you sell it off. The early EFI was garbage and I say that from experience with it. The later version was way better...and I would not convert that bike if it is running. You might want to chuck the stock coils, they were weak to begin with and only get worse with age. I switched and immediately the engine ran better and smoother. Check your coil leads, I had many bad ones as well....and don't forget the plugs, get new modern designed ones.

577nitro