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  #1  
Old 03-25-2013, 01:07 PM
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ocho ninja ocho ninja is offline
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Default Performance head for 99cc/79cc predator

I was browsing aimlessly trough some Parts websites, couldn't sleep.

Been anticipating performance parts for the predator engines for a while from agk and this performance head looks promising. I'm considering getting later on as I get my bike dialed in.

Just wondering if anyone already has tried this head out yet?

http://www.affordablegokarts.com/mm5...gory_Code=99cc
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Old 02-16-2017, 03:00 PM
engineman engineman is offline
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Default Re: Performance head for 99cc/79cc predator

Hello The head is misleading to how it reads.If you plan on getting a 99cc head is what I do mean.Do to they state they no longer can get them.And you have to send your head in tells me all I need to know.When I was interested in that head till I read exactly how its worded.So I don't know how much you know about engines and head work.As I do and plan on doing my own.Its all semi easy really.Once you get the valves etc out.For that you use a simple C clamp to compress the valve springs and remove the small wedge keepers that actualy hold the spring plate or keeper in its place.After that its a walk in the park.Short the valve guides.Which most over look and shouldn't at all.Because any obstruction in the port means less air flow.However, you cant run with out certain parts.So you do the next best thing.And at least tapper the guide material from where its exposed to the top.So when done it looks cone shaped.And the material that holds the guide.You simply reshape into a knifed and ramped ordeal.You want in ramped from one end to the other as the air flows in .You want to run it into the intake valve.So that is how you want to form the shape.Think of it like this.With the knife blade running towards and ramped into the valve area or bowl.And that will be the only area you will actually remove material from.The rest of the port work simply is a smoothing affair.And don't let the polishing word lead you to believe its a mirror finnish.Its not but nice and smooth all over.Should be finished in a 220 grit is about it.IF you see a mounded looking area at the mouth of the intake port.DONT remove any part of it!! Just slightly smooth like the rest.When that will be whats called a velocity ramp.And important to keep.As for milling the head.You can do this also if you know what your doing with a flat solid level work surface.Since most don't know how to perform this.Its best to use a machine shop.I can tell you many performance tips and tricks.But you have to know engines before any to all will make sense.One thing that's very very important to all engines.Happens to be oiling and keeping the engine cool over real hot.No one ever gives that any thought at all.Not to will result in a ruined engine mark my words!
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Old 02-16-2017, 07:33 PM
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Default Re: Performance head for 99cc/79cc predator

Fine advice Engineman!
A pile of porting might gain you a few % more power, likely no more than 5%.
Milling 0.020" off the head might see another few %. Likely no more than another 5%.

One of the biggest thing this head needs is squish area to impart some turbulence, speed up the burn, and resist detonation. While I had the valves out, I'd get a good aluminum welder to zap up some flats by the plug and on the other side.


THEN mill a few thou off to flatten everything up, do the valve seats and all the work you suggest. A cam would go well with more compression and you'd be off to the races with 20-50% more power.

Do you think?
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Old 02-16-2017, 10:06 PM
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culvercityclassic culvercityclassic is offline
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Default Re: Performance head for 99cc/79cc predator

I did all the bells on a 99cc and was disappointed with the results, sold that motor. Its best to just do a carb and exhaust and leave it. You want more power do a GX160 which I think is the perfect size for bike or go 212.
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Old 02-18-2017, 01:53 AM
engineman engineman is offline
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Default Re: Performance head for 99cc/79cc predator

Wow sorry to hear that.I don't at all disagree with your choice of bigger engines.But for one big reason!How will you get it past every COP!I well know many wont know what there looking at.But then count on half to not be stupid.Our state law states 49cc which I cant live with and **** whats 30 more cc.Now to run ether of those and espessially the 212cc GOOD luck brother.When that engine will stick out like a well beaten thumb!Plus for my needs.Anything I'm to build must be completely gone through.That when I'm done.The entire machine spells one word.Performance period.So I will turn enough heads with the one I will be building.The 79cc and I can tell you this.Ive been emailing a tech guy at a performance shop.That deals in all of these engines.Mostly the larger do to kart racing.However they have a bicycle setup with this 79cc and its all pumped up!Huge cam so that's where I'm getting mine.And valve springs.Carb setup and manifold and exhaust.The only other is they milled there head to a whopping 12.5-1!! dynode it at 6.5 hp and he told me.They didn't have great success with the 99cc ether do to clearance for valve and piston.That tied there hands.BUT this 79 predator hasn't the same problems at all.Right down to not breaking down at all.He said we run the **** out of it and then let customers run it even worse! He cant say enough good about it.The other was a greyhound engine. Ok not the same animal at all.Ive researched the predator big time oh my god!To say all of them are a real quality engine and setup for building performance.There all bigger displacement to all others.The 212cc is a stoker engine.That with all the required performance parts and machine work.Happen to be running at 12.5-1 on methanol dude and keep hualing fast ass.Only one guy that went insane pushing his to a insane 15-1 on alcohol did throw a rod through his case.Then most racing built V8 will do the same or bad enough when pushed to that CR.And exactly why any drag raced engines are torn all the way down.And still would be even if they ran a water cooled setup.I used to be in the southern cal speedsking club.I ski raced behind a 950HP dual turbo charged V-drive race boat with a threespeed racing trans.OK and my buddy won his class so he had to go to another.Being flat bottom.So he of course picked the badest that class had.A blown 427 in a Hondo drag hull.That the clown had just ruined by tearing apart the right setup running a lower CR and using gas racing fuel.To methanol and 15-1 CR as fast as he told me that.I walked over to my best friend and told him.GOOD luck as you will not finnish the season behind this boat!Sure enough it went down almost right on the money I placed.To the dime.Basicly it comes down to this.IF you plan to keep any engine running.Keep it no higher than max 10-1 and under 6 grand period.Since this is a tiny dude to begin with.Its going to 11-1 and up to 6grand.When the cam I'm using will run 7 grand and that same guy told me they push it to 7 all the time.So do what you want but expect trouble unless your using it at a track.
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Old 02-18-2017, 12:27 PM
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culvercityclassic culvercityclassic is offline
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Default Re: Performance head for 99cc/79cc predator

Sounds like you found a shop to take your money, the cam, valve springs and head are the common issues. The huge cam, how does it change the clearance problem from the 52 x 37 to the 99cc 56 x 40? Do you have a spec on his cam? This motor with that HP will need a billet rod and flywheel too.
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Old 02-18-2017, 04:49 PM
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Default Re: Performance head for 99cc/79cc predator

No comment on the motor work, but I can tell you right now cops have no idea. Got pulled over a few days ago with license plate off the bike and an expired license. Law is 4hp 30mph <149cc has pedals, well mine is 12hp 55+ 212cc with pedals not hooked up. The cop was looking at the vc406 while asking me the hp and pedals and such, and when he asked my hp? "Ahh I dunno exactly, not much maybe 3 or 4hp whatever the 99cc makes..." no ticket they just told me to put the plate back on and get my license renewed which I've done now.

Looking back I wish I had welded up the cc and used a slightly thicker head gasket for a bigger squish, I'm at 11:1 on 91.
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