HF 79cc Carb Problem

GoldenMotor.com

rgvkid

New Member
Sep 21, 2008
110
0
0
Los Angeles,CA
Its been awhile since I've been on the site because I had the engine stored up in the corner of the garage for about a year.

I pulled the engine out today and it wouldn't start. So I pulled the carb, took out the float and the Piston thats connected to the float which lets the gas flow in, Not sure what its called.
Took out the jet that screws into the center cast tube and I had to clean it out with some .025 welding wire because it was gunked. I ran the wire through the jet that sits up in the cast tube also to clean it out. I cleaned the piston thats attached to the float and the sleeve also. Sprayed carb cleaner throughout the whole carburetor to clean out any gunk. Put everything back together and got it started.

Now the problem is, it will only start with the choke on but the idle is low. When I move the choke back to turn it off, the idle jumps up and it dies. Tried playing with the idle to no avail.

Not quit sure what to try next. Is there a Jet needle on these carbs? Because I don't think there is on this one unless I lost it while cleaning.
I tried looking for a carb Schematic but I can't find anything on it.

I did have to clean and adjust the the rubber tip on the piston attached to the float because when I first put it back together the gas just kept flowing into the bowl and seeping out the overflow all over the floor. So I took apart the bowl and pulled the float and piston again to clean it better and I pushed on the tab a bit to get the piston to seat a bit tighter. After that, the overflowing stopped.

Any insight would be greatly appreciated.
 

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
You most likely still have some residue of the varnished up old gas in the small internal ports of the carburetor body.
Totally disassemble the whole carburetor. Every screw and jet removed.
However there is no need to mess with the throttle control butterfly plate and shaft.
Soak all the parts on Pine Sol diluted 1 to 1 with water overnight.
Thoroughly rinse all the parts clean and blow dry with compressed air. Use a " canned air" computer dusting can to blow out the passages in the carburetor body.
Do the same with the fuel jets.
Reassemble the carburetor and use new gaskets between the carburetor and intake manifold when installing it back onto the engine.
 

rgvkid

New Member
Sep 21, 2008
110
0
0
Los Angeles,CA
So I pulled the carb apart and boiled it in lemon juice for about 25 minutes.
Put it back together and it seems to start up and run but I'm still having a problem with the choke.
Also, I'm not quite sure what the screw is for that's closest to the intake on the cylinder head. I think it's for the low end. Right now I have it out at about two and a half turns.

Here's a video of how it sounds and what I'm talking about. Sorry so blurry.

http://youtu.be/4kwTIEunzoA
 
Last edited:

rgvkid

New Member
Sep 21, 2008
110
0
0
Los Angeles,CA
Hahaha! Actually, the engine was originally on a motored bike I had awhile back then I put it on my Girlfriends Daughters go kart that I built. Unfortunately, Harbor Freight stopped selling the 2.5 engines here in California. I think it went up to the 3HP Predator but you can't get them in Cali. So I swapped the motor over until I can get out of stat and get another 3 HP engine for my Motored Bike.