99cc predator, Dellorto carb, Billet manifold

F_Rod81

F_Rod81

Dealer
Very nice performance modification for the HF99cc! I have combined the 40MM billet manifold and dellorto sha to work well with the harbor freight 99cc predator. The combo should be compatible with the 79cc also, but IDK for sure.

Here is a link to my thread that has the short write-up on the modification.

F_Rod's HF99cc

DSC01405_zpsf97d0f5f.jpg
 
I've been using motorcycle style carbs on these types of engine for decades, ever since my first briggs GoKart build. SO much better throttle response and power I don't see why every preddy or briggs owner does not do this!
Stationary engine carbs are not designed for throttle control and simply don't work as well as motorcycle type carbs do.
Add a good pipe and really wake it up!


EDIT: A stock nt/rt carb and manifold from the china girl kit engine will bolt right on a briggs 5hp with only some drilling to get the bolt hole spacing to line up. A great mod for under $20 bucks!
 
Yup. China girl intake with an RT carb, with 75 jet works great.
A NT also works but needs to be rejetted, and I didn't have any jets that fit the NT.
 
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I know what I'm doing to my 99 Predator before spring comes. Especially nice if you have an extra China girl carb sitting around.
SB
 
This mod has proven to work very well. I found that the timing was off just a tad with the increase. Make sure you guys reset your coil air gap to .020 or .021 for optimal results. I imagine that the manifold design used will have some influence on what type of performance gains and where they show up.

Jet barely lean for max hp
Jet barely rich for max torque
 
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Thanks for sharing this. I had been contemplating swapping out my 99 for a 147CC 2 stroke Jacobsen engine before next summer's riding season. The bike is a 50 Schwinn Panther which is quite heavy with a sidecar for the dog. It wouldn't need a lot more power to be satisfactory, but as is there are hills around where I ride that are iffy. I do not like stopping the rig, getting off and pushing it up the last of a steep grade while the dog looks over at me through her doggles and says by telepathy, "this is pathetic! Can't you push it any faster?" This is the stuff heart attacks are made of, so I do not like trying to pedal a freight train or pushing one any distance either.

With your simple modification I am guessing this will be enough to make the critical difference. I'll try it first with a stock china girl carburetor and intake manifold and if need be will go up from there. This will be a whole lot simpler than replacing the engine!
And so I thank you sir!
SB
 
I'm hooking up an NT that I had handy but didn't think about the vent tube from the valve cover. Is this tube for suction to help draw oil to the valve or is it just a vent that needs filtered?
 
Stormsorter said:
I'm hooking up an NT that I had handy but didn't think about the vent tube from the valve cover. Is this tube for suction to help draw oil to the valve or is it just a vent that needs filtered?
Click to expand...

It's a crankcase vent. It helps rid of extra gasses and blow-by. Some applications will have a dry tube, others you will see minimal oil deposits (blow-by). There is no negative to having it off and/or out, except that your engine will get dirty faster.

you can...

1. just cut or remove the tube (old school and dirty)
2. install an actual breather filter (more modern and cleaner)
3. route the tube to go back into the air-filter (recirculates blow-by and gasses)
 
Thanks for the info but I already threw a fuel filter I had on it. Rural King tricked me, they changed there $5 paper filter to a mesh style and now I have a use for the damn thing hehe. I mite even cut it open and put some material from the stock filter box in it.
 
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