Thoughts on this 4 stroke engine

[Chainlube]

I have been trying all kinds of little stuff with the pred 79 and I have come to the conclusion that you either spend a mound of money or just enjoy the gutless wonder as it is. You will spend a huge amount till you finally figure out it isn't worth it cause its still just a 79.
Don't count on AGK to be bringing back stuff either cause last time I emailed them they said they moved on from the 79 and that was before you talked to them about the carb they use to have.

They're just nice subdued engines for kiddy machines. I have one on a mini chopper.

 

[Chainlube]

Oops forgot from my findings so far is stick with the stock carb instead of the PZ19 unless you are going to spend the mounds of money you will need for that carb and manifold to work properly.

I made my own manifold.

 

[meridianPeteJ]

Well I was way wrong they do have carb again

Carb, Bored & Reworked, 79cc/99cc

12300 This is a stock carburetor that has been bored and reworked. Carb now has a .487" bore (stock is .428"). Circuitry has been reworked and butterfly and shaft have been modified. Shipped with a #82 main jet (this latest batch has a couple with a #78 jet drilled to a #82). Direct replacement...

affordablegokarts.com

 

[michael whiteman]

Thanks Pete. They told me there would be more coming, and like everything else the price is $20 more. I ran the numbers and the reworked carb has 29.5% more area than the original. I don't know how that equales to CFM air flow but Cruzr47 told me he could really feel the difference with his. You can get a PZ-19 with a manifold for close to this new price if you're willing to redesign the throttle cable etc.

I know they narrow down the choke and throttle shaft but I wonder if they also bore the outlet diameter and install a larger diameter butterfly? Their video doesn't explain that. Increasing the throat diameter without increasing the output (which is 15mm) will definitely change the vacuum reading over the main jet discharge from how the manufacturer designed it to be. Less vacuum would make it harder to suck the fuel out the port. Hummmm...........

 

[meridianPeteJ]

I have found that the 82 jet they put in that carb way to big for the predator. Thats even with a free flowing exhaust and air filter.
I think they just bore out the center part of the carb so you wouldn't need a different butterfly well that's at least my theory.

 

[meridianPeteJ]

Now that we have done hijacked this thread my thoughts on that motor is I would try it and I know there was a guy on here for a while that had it on a bike and did quite well with it. Think he had it up to 45 mph after a valve adjustment and maybe a new clutch.

 

[meridianPeteJ]

This one

Finally got it dialed-in

Finally got my 100cc (79cc) Predator clone kit done! Put on 35 miles over the last few weeks. Got it to 45mph (still has governor). Rides smooth, reliable, sounds good! Sounds like a little 4-stroke pit bike. Had to buy a replacement carb and install new clutch, and adjust valve lash. Pretty...

motoredbikes.com

 

[michael whiteman]

You're right about this thread taking a hard left turn Pete. Bits and pieces of great information show up here and there so if it pretains to you ya better cut and paste it somewhere for future reference and safe keeping. Case in point...........the 82 jet you mentioned. I was just about to make that upgrade, but now I won't. Thanks Pete. I have found enlarging the pilot jet takes care of the off idle lean spot and continues to add fuel to the air stream at WOT. I think I'll enlarge mine a little more now.

And I tend to agree with you that the output of that modified carb is still 15mm like the original.

 

[GodMan]

@michael whiteman Are you saying your Hausheng engine tackled the hill better than your predator 79cc?

 

[michael whiteman]

YES ! But be informed, it is due to the lower gear ratio. The Predator has over 2.5 times the horsepower. If you need to climb hills you will not be going as fast on the flat and level. And visa - versa. You will have to decide where the compromise point is for your type of riding.