1980 KZ750E Petcock/Carb issues.

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First post here. I've had my 1980 KZ750E for a week now, and yes, it is my first bike.


Rode to work this morning, and when I stopped to fill up I noticed fuel was intermittently pouring out of my 1 and 4 carbs. I frantically rode home and then panicked for a while.

After some discussion with a friend and some time, I came to the following deductions: I have a stuck carb and a busted petcock.

Based on my experience, I would like to present a few options I've come across for my Petcock issue. I would love any opinions, or to point out anything I've missed.

OPTION 1: get a rebuild kit.
Something like this:
The issue here is that I still have a vacuum petcock. After today, I would really like the ability to manually turn off the fuel.

OPTION 2: get this petcock:
www.speedmotoco.com/product-p/smc-44.htm
Would this be a bolt-on for me? Would it work fine? If so, I think this is my favorite option.

OPTION 3: get an adapter plate and a universal petcock.
www.partsnmore.com/parts/kawasaki/kz750/...s%5Bcategory%5D=carb
Seen em here, dime city cycles, etc. I'm assuming a 44mm adapter plate and then whichever petcock I want.


Is there another option I'm missing? A different bolt-on manual petcock replacement?


Apologies in advance if this question was answered on another thread. I have tried to do my due diligence of forum searching, but I may have missed it...


Thanks,
Ray

K&L parts are made in Japan & oem quality IMHO. Some guys prefer genuine Kawasaki parts --- the diaphragm etc may still be available at the dealer. Before rebuilding the petcock, you should disassemble, clean & inspect it. If the thing appears to be in good condition with no pitting or wear marks or anything, then a quality kit will probably work fine.

With some aftermarket fuel valves that use the adapter plate you have to ream out the fuel screen hole 2-4mm. Keep in mind that sparks can occur --- sparks + gasoline = boom. :ohmy:

If the bolt hole spacing is 34mm & you'd prefer a manual fuel valve, the linked topic has some options. Manual fuel valve option

Hi there
Option 1
If you take this route then Martin's advice is spot on. In addition, when you dissassemble the percock you will find a small spring in there. Stretch is out a bit.

Option 2
Looks good. Make sure / measure your existing hole spacing. The speedmoto website saye its for a 1980 H1. There is a slight difference in Kawasaki part numbers for the E1 and H1 petcocks but they both have the same oval O ring between the plate and the tank so it should fit.

Option 3
I'll leave this for someone who has done the conversion

I actually like my vacuum petcock. Trouble free for the past 10 years. Your leaky carbs could be a stuck float, crud (get an inline fuel filter if you dont have one) or a needle seat problem.
You may have to
clean the seat with a Q tip soaked in carb cleaner
clean the seat with a Q tip and Brasso - worst case
or get new float needles ( inexpensive)
or all of the above

Slainte

Regarding the petcock - (no offense intended) Was in the RUN position not PRI? Sometimes when a bike is new to a person they make little mistakes that seem like biggies. Ed

none taken -

No, it was in the run position. putting it on primary made it pour even more.

Sounds like you have a stuck float.

Before making any purchases I would do the following.

Drain the tank, and remove the petcock. Disassemble and look for any issues. Tears in the diaphragm, etc. If there are any issues you can actually buy just say the diaphragm from z1 or the whole petcock kit if you feel it's necessary. Once you have it off and apart you will know. You can also try disconnecting the fuel line and turning the valve on the petcock to see if your leak continues.

Second remove the carbs and clean them thoroughly. Check float seats and float bowls are adjusted correctly.

I thought mine was bad on my 82 but I pulled it off the tank disassembled it and it works fine. I did have issues with gas coming out of carbs at one point but this was during operation and I had stuck floats. I ended up cleaning my carbs at least 6 times before I got it to all operate correctly!

I had the same issue when I bought my bike. I drained ALL the gas from the tank, and the carb bowls. Poured straight seafoam (about 2/3 can) into my tank, turned petcock to prime, and let the carbs fill up. Turned he bike over a few times to get the seafoam sucked up into the carbs, and let her sit 24 hours. Came back, drained the seafoam via the overflow tubes, filled up with 100% gas, and no leaks....

May be worth trying before you start disassembling stuff, a can of seafoam is 8 bucks....

leaky float valves are very common on old bikes, had this on my GPz750R1. Often carb 1 which collects all the crap when bike is parked on sidestand.

I replaced it a pattern part which seems to have fixed it.

Those 750E are really nice bikes and well worth getting your hands dirty on.