I would just like to know if any of you have had some flat spots on your haitachi carburettor and how to fix it?

Flat spots don't happen with the 71-73 carbs, but the newer ones might have them depending on the emissions controls (anti-pollution). Rejetting (including the accelerator pump) might help.

It's common for a vacuum leak to cause a flat spot when you first give it a little throttle. So check for leaks, including check for worn-out throttle shaft.

How would you describe the flat spot?

reference: Carb adjustment, troubleshooting, rebuild and inspection

What happened was i baught a new carburattor kit and i installed it and after that the problem started.To describe the flat spot:When the motor is cold and you put foot its like you put your foot on the brake and gas at the same time and then it goes like a bomb,when the engine heats up its a bit better but does the same thing when you put foot

Yes, that could be called flat spot. We might even call it "hesitation". There might be a vacuum leak, or a gasket that doesn't fit right ... sorry I don't know for sure, hard to say without seeing it.

if it started after u did the carb have a look at ur acel pump anr r&r ur jets clean blow out with comp air if #### is in the fuel bowl look where its coming from dodgy fuel filt? or outa ur fuel pump ?

you could have an air leak maybe? though the manifold or somewhere, put your hand over the carbie while its running see what happens?

i had the worst time with my Hitachi serious!!! i tired everything, i then found out the solaiond was rooted i was missing a secondary idle jet and the carbie its self was wrecked! so i bunged it all in the bin and got a weber nad have never had a problem since!!

Yeah, if your carb is ruined, replacing it is not a bad idea. I replaced my Weber with a Hitachi and never had a problem afterwards ... no joke. The Hitachi is one smooth carb (unless there are missing parts, hehe). But the Weber lets the engine rev more.

A-14s carb should be repairable (no need to replace). If it didn't have the flat spot before the carb kit, then it should be fixable...

I have to say ddgonzal did a good job in helping me out on a similar problem on my A12's hitachi carb. Check out his article.

Bottomline, the possible cause were:

- A leak in the vacuum.
- Air getting inside the fuel reservoir of the carb due to "air leak" in the carb top gasket.
- A non working plunger.

One more thing to add was the fuel level inside the carb was too low. When my mechanic tried to increase the fuel level inside (this was beyond the factory specs) I solved the problem. The catch here is that the level should not be high that it chokes itself.

my 2 cents.