Predator 79cc carb question

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PAracer

New Member
Sep 14, 2012
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Steelton, PA
I am interested in boring out my 79cc engine's carb. I've got a question about it's disassembly.

How do I remove the tube that sticks up into the venturi? I tried pushing it out through the inside, but no progress was made.

So is it glued in? Do I need to heat the carb body? Do I smash it with a big rock?

I have already knife edged the choke butterfly, and narrowed both of the shafts.
 
scotto-

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
24
38
Ridin' inSane Diego, CA.
PAracer said:
I am interested in boring out my 79cc engine's carb. I've got a question about it's disassembly.

How do I remove the tube that sticks up into the venturi? I tried pushing it out through the inside, but no progress was made.

So is it glued in? Do I need to heat the carb body? Do I smash it with a big rock?

I have already knife edged the choke butterfly, and narrowed both of the shafts.
Click to expand...
If ya don't find a suitable answer to your question, just buy an 18mm-22mm mikuni or walbro carb and dial it in.
 
P

PAracer

New Member
Sep 14, 2012
284
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0
Steelton, PA
I think I'm going to try a bit of heat to see if I can loosen it up. I've seen references to some that have the tube glued in. I'm hoping that this one is the same.

Thanks Scotto. I'll look at picking up one of those carbs if my plans don't pan out.
 
scotto-

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
24
38
Ridin' inSane Diego, CA.
PAracer said:
I think I'm going to try a bit of heat to see if I can loosen it up. I've seen references to some that have the tube glued in. I'm hoping that this one is the same.

Thanks Scotto. I'll look at picking up one of those carbs if my plans don't pan out.
Click to expand...
You might try to get a hold of Shane at AGK trough a PM or phone call. He rebores and reworks these same carbs and could prolly answer your questions. It's worth a try. User name: agk. Website: http://www.affordablegokarts.com/index.php

dnut
 
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PAracer

New Member
Sep 14, 2012
284
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Steelton, PA
I went the easy way out. I stripped it down as much as I could and used a dremel to enlarge the bore. I'm not sure if I went as far as is possible, but I'm sure I improved it a bit. I also radiused the lead in to the venture, and rounded a couple other places.
 
scotto-

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
24
38
Ridin' inSane Diego, CA.
PAracer said:
I went the easy way out. I stripped it down as much as I could and used a dremel to enlarge the bore. I'm not sure if I went as far as is possible, but I'm sure I improved it a bit. I also radiused the lead in to the venture, and rounded a couple other places.
Click to expand...
Keep us posted on how it performs.
 
Longshot270

Longshot270

New Member
May 8, 2012
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Texas
The guy at AGK can bore it out with much less hassle.

I was going to get him started on a whole new order to give me a spare carb but he said he couldn't give me any kind of timeline for expected arrival.

Before you spend a bunch of money, try isolating the valve cover breather. That had the greatest improvement IMO. The engine would finally idle smoothly below 1800 RPM and became much smoother across the entire RPM band. I used a brass 3/8 barbed nipple and a standard automotive manifold breather filter. Took some work to get the nipple into the valve cover but it has been solid since...even after getting smacked into some tree branches.

My application is a little different but the results should be the same.
 
P

PAracer

New Member
Sep 14, 2012
284
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Steelton, PA
I will report on the result. WE a gearing up for vacation here at the house, so I am a little preoccupied at the moment. I will try to get the bike on the road in a day or so if I can.

I have already rerouted the breather. It is tucked up under the saddle. I did that when I swapped in a cone filter. I am using AGK's adapter and high flow cone filter. The adapter is modified (queue dremel theme song) to create a bit of a velocity stack.

My motor:
79cc predator
Custom exhaust. (I went oversize on the pipe diameter just for looks)
RLV silencer
AGK filter adapter and cone filter. (adapter modified as described above)
Carb bore enlarged with dremel
Carb shafts narrowed to reduce obstruction
#82 jet
Port matched intake manifold (The black plastic spacer)
Governor removed.

As far as drivetrain, I am using the AGK jackshaft, max-torque clutch, and a 56 tooth sprocket.
 
P

PAracer

New Member
Sep 14, 2012
284
0
0
Steelton, PA
Just went out for a little right.

I am positive that my dremel work on the carb has made an improvement. We have some steep hills here in the neighborhood, and I can chug right on up to the to the top at a pretty good clip. On flat land the bike wants to dump me off the back of the seat.

This little free mod is worth it. I don't know if it's as good as a storebought carb.
 
scotto-

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
24
38
Ridin' inSane Diego, CA.
PAracer said:
I will report on the result. WE a gearing up for vacation here at the house, so I am a little preoccupied at the moment. I will try to get the bike on the road in a day or so if I can.

I have already rerouted the breather. It is tucked up under the saddle. I did that when I swapped in a cone filter. I am using AGK's adapter and high flow cone filter. The adapter is modified (queue dremel theme song) to create a bit of a velocity stack.

My motor:
79cc predator
Custom exhaust. (I went oversize on the pipe diameter just for looks)
RLV silencer
AGK filter adapter and cone filter. (adapter modified as described above)
Carb bore enlarged with dremel
Carb shafts narrowed to reduce obstruction
#82 jet
Port matched intake manifold (The black plastic spacer)
Governor removed.

As far as drivetrain, I am using the AGK jackshaft, max-torque clutch, and a 56 tooth sprocket.
Click to expand...
My most recent build has most of the things you mention here.......good stuff!



That is the AGK bored and reworked carb, my home made 1" OD square intake manifold with bored out black plastic spacer and the exhaust is mostly 1-1/8" OD round tubing with a mini RLV silencer exiting right by the rear axle. Governor also removed and using my own jackshat set-up with 2-disc Noram "Cheetah" clutch.
 
P

PAracer

New Member
Sep 14, 2012
284
0
0
Steelton, PA
scotto- said:
That is the AGK bored and reworked carb, my home made 1" OD square intake manifold with bored out black plastic spacer and the exhaust is mostly 1-1/8" OD round tubing with a mini RLV silencer exiting right by the rear axle. Governor also removed and using my own jackshat set-up with 2-disc Noram "Cheetah" clutch.
Click to expand...
Nice!

Is there anything else available for these little HF engines? Valve springs? Billet flywheel? Camshaft?
 
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