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Discussion Starter · #1 ·
I bought a replacement carb for the Kaw FH721V on my ZT:
Partman Carburetor/Carb Kawasaki 15003-7080 Replaces 15003-7048 Fits FH721V Engine https://a.co/d/axPoP5h

It started right up after the swap but it does surge badly at all speeds under no load.
Are there mixture screws under the caps near the fuel bowl elbows?
Which ones?
Gas Font Machine Metal Auto part
 

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Here is the service manual, go down to the Fuel System section, you should find what you are looking for. Good Luck
 

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Discussion Starter · #5 ·
Let's say for the sake of argument that I agree that most Amazon-sourced Asian replacement parts for this Asian engine are junk.
Well I chose the one good replacement part & it needs adjustment. Runs a bit lean & will smooth out with some choke added.
The manual doesn't describe how to adjust for best performance--it only says to count turns into the seat. I feel that's a cop-out that'll only get you "in the ballpark".
 

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Why did you need to replace the carb in the first place ? What was the original problem ?

Well I chose the one good replacement part & it needs adjustment. Runs a bit lean & will smooth out with some choke added.
The kit you linked to shows 2 intake gaskets. Did you replace the original gaskets ? Did you test for an air leak before you ordered the carb ?

The manual doesn't describe how to adjust for best performance--it only says to count turns into the seat. I feel that's a cop-out that'll only get you "in the ballpark".
There is no hard number of turns for tuneing a carb...Every carb that I have "tuned" was done by ear. And I have never had to tune a new oem carb out of the box.....

That being said, you either still have the original problem, or the Chinesium carb you got has a problem.....
Have fun playing with that carb, you can figure it out.
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Drill a small hole in the cap and use a contruction/deck screw to pull/pry/pop the covers off to get access to the adjustment.
If there are any. It might be a fixed jet. Since you own it already, and are sure its getting fuel, take it apart. There might be drilling debris. Sometimes the 12 year old worker screws up. Must have forgotten the last thrashing. LOL
 

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Wow I remember when this site was a source of useful information & help.
Trying to help you buddy! Those carbs are nothing but junk trust me. We used to try those for customers because we'll they were cheaper, but no matter what they always were junk, most did the same thing you described. I would highly reccomend taking your carb to a good shop that can clean it good in a ultrasonic cleaner and add new seals for you (we usually do it for around $20 plus seals cost and there's not many that don't come clean). If that doesn't help, and you are sure you have good fuel (no ethanol, trash, or water in fuel), good fuel pressure out of the pulse pump, then it's time to buy a OEM carb (yes they're high 200-300 bucks). But those cheap carbs are a complete waste of time.
 

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Everyone keeps saying that the tamper caps are on for government regulation..... that isn't the case.
They are on there because no one will leave screws alone who don't know what they are doing. They would take a new machine that wasn't running right and mess with those until it was way out of whack and them bring it in under warranty. Manufacturers got tired of people fooling with them and having to pay a warranty claim, so they capped them. It has nothing to do with regulations.

Now, the fact that everything is running super lean, that is for emissions. Less particulate emissions with a lean mixture. But they changed jet size to accomplish that. Even with a fuel screw, it's almost always still too small a jet. You bring it out so far and it can only get so much fuel. It's not large enough to be able to get too rich.
 

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Everyone keeps saying that the tamper caps are on for government regulation..... that isn't the case.
They are on there because no one will leave screws alone who don't know what they are doing. They would take a new machine that wasn't running right and mess with those until it was way out of whack and them bring it in under warranty. Manufacturers got tired of people fooling with them and having to pay a warranty claim, so they capped them. It has nothing to do with regulations.

Now, the fact that everything is running super lean, that is for emissions. Less particulate emissions with a lean mixture. But they changed jet size to accomplish that. Even with a fuel screw, it's almost always still too small a jet. You bring it out so far and it can only get so much fuel. It's not large enough to be able to get too rich.
Makes sense but If I remember correctly my friend who owned and ran a mower sales/repair shop for 20+ years told me that in California those caps were installed to keep emissions down. The carbs were set lean at the factory and yes, they didn't want anyone messing with them.
 

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Makes sense but If I remember correctly my friend who owned and ran a mower sales/repair shop for 20+ years told me that in California those caps were installed to keep emissions down. The carbs were set lean at the factory and yes, they didn't want anyone messing with them.
California is a different country than the rest of the USA.
 
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