Topic: 1974 550 engine popping at acceleration

[Sellouma]

hello everyone,
my name is Sam, I am a new member and happy that I joined such resourceful forum.
I acquired a non running 1974 550 for $400.
The bike came with pods and 4into1 exhaust, main jet #120, slow jet #38, needle position clip at the 1st notch at the bottom.
Inspection of spark plugs showed black soot.
gas tank was little bit rusty, took off the fuel valve and taped the hole with duct tape( )and used muriatic acid to clean it, left it for 24hrs (BIG mistake!!!) put the gas tank on top of the bike overnight.
The following day, I was in for a horrible surprise! the tape came off and the acid was dripping on the intake manifold and the cyclinder fins, it was bubbling!
I replaced the intake manifold, I was lucky the acid didn't destroy the cylinder.
I cleaned up the carbs and switched to 110 main jet and 38 slow jet, needle clip in the middle and put new spark plugs, I had trouble making the bike run because of the damn choke can be confusing on the 550 ( I was using it the wrong way ), and I was having black smoke coming off the exhaust. I worked on the carbs like 6 times!
now, i am running 110 main, 40 slow jet, no more black smoke but when I blip the throttle, it detonates and dies.
I tried to take it for a ride, but when I put it in first gear and give it gas, it stumbles and dies!
I took a video of it:

I am sorry if I was annoying with the details, but wanted to provide as much details about the bike to help narrow the problem.
Any help is duly appreciated!
you guys are awesome !

[Pielz]

Oh my gosh. Yeah muriatic takes like minutes to work! It's much stronger than vinegar.

[Sellouma]

Oh my gosh. Yeah muriatic takes like minutes to work! It's much stronger than vinegar.

very true, and I only learned that from the second time I used it for 5 minutes to get rid of the rust that formed in the tank, as I dumped the acid and left it empty. you live and you learn!

[Pielz]

Definitely!! Well I'm glad the tank didn't spring any leaks. I won't be much help with your other issues unfortunately as I get by with carbs by the seat of my pants as it is. I'm a newbie to this stuff. But good luck with everything else!

[Sellouma]

Definitely!! Well I'm glad the tank didn't spring any leaks. I won't be much help with your other issues unfortunately as I get by with carbs by the seat of my pants as it is. I'm a newbie to this stuff. But good luck with everything else!

No worries Pielz, thank you!

[DaveBarbier]

First I would get a manual and go through the 3k mile maintenance check list. You can download it on this site. Cam chain tension, valve tappet clearance, ignition timing, etc. It’s in the manual and essential to do before moving on to carbs. Also, get a new set of spark plugs. No sense messing with potentially carbon fouled plugs. Stock NGK kind. NOT iridium.

That being said, I would bet the carbs are clogged from sitting and from any debris that got into them from the tank. After the 3k mile checklist I would remove the carbs and clean them very thoroughly! Remove all jets and clean with carb cleaner and thin wires and compressed air. Ultrasonic cleaning is best if you know someone. The jets themselves (especially the pilot jets) have tiny holes in them that HAVE to be clear.

[Tom C]

That Kawasaki tank sure looks good on that 550! 

...so at this point the popping at acceleration thing in the thread title is no longer the problem? 

Good luck with the fixing - I can't help you but the wise folks on this forum are sure to give you lots of good advice!

[Sellouma]

First I would get a manual and go through the 3k mile maintenance check list. You can download it on this site. Cam chain tension, valve tappet clearance, ignition timing, etc. It’s in the manual and essential to do before moving on to carbs. Also, get a new set of spark plugs. No sense messing with potentially carbon fouled plugs. Stock NGK kind. NOT iridium.

That being said, I would bet the carbs are clogged from sitting and from any debris that got into them from the tank. After the 3k mile checklist I would remove the carbs and clean them very thoroughly! Remove all jets and clean with carb cleaner and thin wires and compressed air. Ultrasonic cleaning is best if you know someone. The jets themselves (especially the pilot jets) have tiny holes in them that HAVE to be clear.

I have the manual, went through Cam chain tension, valve tappet clearance. the bike came with an electronic timing ignition.
I also installed new NKG spark plugs.
I previously mentioned that I cleaned the carbs like 6 times (ultrasonic cleaned) and replaced jets, so dirty carbs are out of the equation.

[Sellouma]

That Kawasaki tank sure looks good on that 550! 

...so at this point the popping at acceleration thing in the thread title is no longer the problem? 

Good luck with the fixing - I can't help you but the wise folks on this forum are sure to give you lots of good advice!

It is still the problem.
the kawi tank was just for mockup. it was leftover form a previous built, that I couldn't finish, as the bike got impounded by the cops for missing inspection sticker( welcome to NY!).