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!
 
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.
99ccCylHead.gif


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?
 
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.
 
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.dnut
 
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.
 
Ive no doubt that did happen.When Ive got out of more than my fair share of real issues with cops.But that hasn't twisted my thinking process into that will be the norm.Bottom line is cops are people only which have badges.With this we all should know.Theres more good people than bad.But not nearly enough to make for clear skys and smooth sailing.Before you know it the day will arrive.With the ******* at your side.And he wont let you go till he finds some reason to give you what he pulled you over for in the first worst place.Or used a lame one.You had best keep wishing or maybe thinking your fine.When all I do know is this.I see you have a license plate.Which is the only way around it.As long as you have a motorcycle operators license to go with it and insurance.At least that is how it is run here in Arizona.Dude they will pull you over for any damned reason! When some will make one up ok.WHY? Why not when this is all about $$$$.That you wont get without a ticket and more can only get better.And not every cop is bad with engines.When if I was one Id be your worst nightmare.I know right off by a quick glance about what cc to cubic inch it is or is not.And I know theres afew cops just like me.Years ago I got nailed by a DPS officer while riding back to my cabin from flagstaff.With a friend on back of my KZ 1000 a old super bike type.Cammer header etc At the time there wasn't much that would beat it.I was doing 85mph when then it was 55 limit.I came around a mountain curve and seen him in the left interstate lane in front.And he not only seen me but knew I would be speeding.LOL **** the bike looked fast standing still.So he slowed down and crossed over to the north bound lane and took off.So did I get back to 85 and before I knew it there he was right behind me!When I walked to him,he told me you didn't expect me to pull that one on you!Why I did was when I had to as your bike will out run this car.It would but not with me on it and it wont out run your radio!From there things got better as he was a nice guy.Like most want to hear something honest and senseable.He told my cousin you come here your getting one too! He tried telling him it wouldn't do the speed my bike was.The cop laughed and told him the year and exact model of his bike.Then he told him the top speed it would do.So there it is for anyone that ether wants to believe it or not.Thats up to you.All I know is I don't want to get pulled over and when I do.I don't want to be telling anyone what I well know better not to be true.Starting with the complete look of what I'm riding will tell anyone with four brain cells.Im full of bull when you cant buy what I'm going to build.And being a street cop they see plenty of them.And not one at all like mine.LOL it will look faster than it really is.When Ive decades of all types of hands on working knowledge for building all types of things that all pertain to go fast vehicles of different types.From engines to metal fabrication and custom paint etc.Except on this build the only thing to see paint will be the engine.As in block and cylinder.The rest will be ether satin finished aluminum with all stainless allens or powder coated.Except the exhaust that will be all stainless.Not a straight pipe ether..wee.
 
Re: Clearance problem on a 79cc..........

I don't follow you,when I said in my last email I believe.That there isn't any clearance problem with the 79cc.But there is on the 99cc so I was told and why the shop didn't like it and tossed it for this engine.I don't know the exact cam specs but close enough.Stock is 170 that's all the shop told me ok.As the duration must be the same less what was added for lift to the new cam.You do get duration in lift as well.When it takes more time to climb a taller tree.Along with the same to get back down.The bigger cam they offer is a 241 lift The head is the same you sent in is what you will get back.Only ported and milled if you have the 99cc you have to clearance the piston with valve relief machined into the required spots.Heres the good news for anyone with the 79cc.When this shop has done a real job reworking theres.And have punished it and dynode the mini beast.To get 6.5 hp from it.And run it long and hard without any problems.Theres is at 12.5-1 CR with there cam and 26 lb springs.Turns 7000 rpms Full port and polish and carb work.I know they are not running the carb I will.When no one is and why? They don't know is my guess.Then Ive my own way of how I go about doing things.When it comes to carbs and intakes.Its all about building velocity and getting it out the same way with a slight twist on the back side.In this case the other side.The only other thing I ever had with the engine in backwards was a old drag boatA howard flatbottom V-drive with a pro built big block ford.That I used for water sking and training behind.As I was in the south cal speedsking club.Sking behind a boat a lot faster than mine wasn't.It came my way oddly enough with the perfect gearing for all around waterskiing.As long as you didn't ski over 80 mph that is,.What it lacked on top end it more than made up for on the low end.One of very few boats that would pull out six skiers now!And still have gas pedal left over.Now as for a billet rod.GOOD luck when no one makes one for the 79cc.They told me they use the one and only it came with.So far so good.No doubt when my boat ran stock ford rods.And crank but then ford stuff is STRONG.Mt buddy ran the same engine as I had in my boat.In his monster mud truck with a bottle of laughing gas connected and used at every mud race.With exception of heads and pistons and manifold and he ran a single carb dominator.I ran twin 750 holley 4 barrels.With a set of heads that made anyone who knew what they were looking at FREAK out!As they were closed chamber with a radial port job.Which out performed the 427 heads I had to use later after those cracked.xct2
 
Even a single 750 Holley is too big for the 99cc engine. You digressed! :)
Otherwise, great stuff in there. Paragraphs would make it easier to read.
 
I had two identical bikes, both with HF79cc engines. One was stock with added 18 lb valve springs, the other had a cam, springs, head work. The stocker would beat the built motor in a race every time. I put the stock cam back in and it ran much better. I felt the bigger cam was causing the intake charge/flow to slow down. The HF79 is a good little engine but by the time you dump any money into it you could have just gone to a bigger engine. Nothing like displacement.
 
IF you had taken the time and paid real attention to what Id said.Then youd read that the holleys!Not one but two of them were in fact on my pro built 390 which was bolted to the stringers of the flatbottom V-drive boat I had and ran for years!To big **** the engine would start do to flooded if you could figure the way to mount it!The fact is anything larger than the 24mm flatslide I will use is to large.Some may like to think it maybe.When the truth here its not, but just right for what I use it for.Ive used mikuni carbs that were in fact to small on Harleys as far as the throat of carb.But that's only for those like me who now know better about air and flow.Because fact has it you can go ether way.For larger or smaller and this is what to expect. Smaller carn you will have to increase the jets for fuel and the larger decease for fuel.The smaller carb will give you slightly better low end to mid range power.While the larger will not lend to low end as much but will without question from mid range to a better top end.And more rpms.My reasons are more than that.When I build a system that will all work together.For when done right.I wont loose much if noticeable.Low end power.Do to how I go about the porting and the inner air ways that I have to build when I make my own intake manifold.And velocity stack to fit the carb.All must fit perfectly and the mount side of the intake must match the port.From there the intake will slowly grow to the size of the carb.And the velocity stack will match and then it will grow larger.With all of it to match the finnish of the ports which will already be done in a swirl finnish.What all of this will do for the engine.IS build real air velocity and also mix it well and with the use of a flatslide carb.That lends more air flow when compared to the round slide.And more torque and power through out the entire rpm range.IF that's not enough it also acts like a poormans super charger.When in fact that's exactly what it is.Someone had commented about the percentage of power to get from porting and milling the head.They happen to be very off base!They used a figure of only 5% Where did you get your numbers at or from?? ALL wrong! Then it would depend on what type of work is done.When I know numbers and numbers don't lie when you use the right numbers.Afew decades ago.I used a solid software program by wingnut.That in fact was a article in hotbike magazine then.All about how good and a stand alone program it was.I wanted to learn a pc back then.But needed something to want to get on one.And that was it and in 1990 it cost 200.00 came on a floppy disk.My girl friend at the time was a pc programmer and couldn't see what I paid all that % $$ for?LOL she knew knowing about engines Harleys and real performance!That program flat rocked! And in fact was the best thing I ever did or used and bought pc related in my life! Like anything to use it to its fullest.You had better have a good working knowledge of engines and performance.I sure did when I spent many years riding and racing.From age 14 by age 16 bought my first race bike and by 17 was racing and doing all the wrenching on it period. When I got the program I was in my late 30s.And wanted to build a good solid performance engine for one of my Harleys then.I wanted it fast but reliable.So I already well knew what needed done.But not the right camshaft to use? I did when I was done learning and running all the different print outs I did for months.So you tell me if I understand port and air flow or not.Compression and how it works together. When the cam alone will reqire a compression change.Depending on the cam will require how much compression you will need.Point here is just port work ok.And the port work done then added a additional 15% solid 15% all by itself hows that!Sit down and shut up and learn.When all I did to that engine was mill the head one point up being 9-1 from 8-1 and a full port job in fact with tapped valve guides when not to isn't a good port job ok.I didn't use thin stem valves do to the cost.The cam wasn't much at all in gross lift from stock but it had a ton in all duration added in.Allowing for use of stock valve springs! So many reason not to mess with all of that for what gains.Unless drag racing period.Now the gains I seen on paper print out from this program with all solid numbers used.Told me I went from 69hp to 83 hp I'm here to tell you this much.Not but afew Harleys ever stayed with me period.Then for what my bike lacked for power Id make up for in riding ability.Take me to a two lane twisted road and Id blow your doors right off. And I did every single time with all I was with only one guy and only once did he get me.And we weren't on the same type or kind of bikes.So that depends upon whos looking at what fair.
 
Well that to all depends.On the displacement and in your case with two same bikes and one with a cam reguardless of the springs.In your case that is.Heres exactly why your stock engine outran the camed engine period.YOU never just use a higher lift or duration cam without increasing your compression!NEVER do you want to know why? When you lost the most important thing you barley had before the cam.Called compression!Do to the valve overlap is it.As for displacement that to can be overated. And is unless your talking a lot more period.So for those who have more money than brain cells that work then yes in every case your right.Because for anyone that knows and will do things right Its impossible for any stock machine to beat one not.dance1
 
And as for all this performance stuff.Unless you have the facts or want to know why that maybe didn't work.Dont just come at me like I'm the one that doesn't know what I'm doing.When so far that's what Ive got from anyone that had anything to say without any positive in the words.Because I know of many ways that you can screw up a performance engine.Only that's not what this is about.But since I'm on it here one is.Exhuast when in fact all but the best seriously built engines will want some back pressure to run right.Only the largest and most built displacement can and like to run wide open exhaust.And at that theres a law for length.That begins in shorter is better than to long.Just as the diameter to be used.Ive found out at least when it comes to buying exhaust.Dont ever think without better knowing.No matter what some like to say.That it will work on yours.Unless you have witnessed it first.I bought a free flow system once for a four cylinder engine with plenty of mods.But not enough to stray from the correct diameter and flow required for the hp.When it showed up before opening the box I had a feeling I was in trouble.When it stated for use with ether four or six cylinder engines.WRONG! OF course I got the larger one.So I tried it to see if for any reasons I was wrong.I wasn't at all it was a worthless product at best for any four cylinder at all.When I had the largest made then period.Good news was do to that was how I owned my first super trap. Unlike many mufflers this one isn't in any way crap.IT rocks and works great for all not a force feed induction.xct2
 
Re: 79cc performance vrs 212cc displacement

What Id not said to the guy that states displacement will out win performance.When the performance is used on a smaller displacement engine.That only depends on how much difference to start with.And exactly what your after in the engine is another.When in this case, the 212cc will always put out more low end and top end power as it will also for overall torque.However in ether case as with other engines.Anytime you build a true performance engine.OR just do afew changes towards the performance end.As long as there the right choices and there done right.Then the engine will always beat the same in displacement.And it wont matter if its up hill or down or whatever.The only place the stock will gain.Will be in fuel mileage and cooling first off.And the stock engine when taken care of will go longer for the mileage meaning run time.When this is all simple to figure.As any engine is nothing more than a fire breathing air pumpMore air in and out is one way of making them faster but not so much more powerful.Till you start with these.And those would start with compression and camshafts.I say CR first when honesty that is what does add the most power quickly.And the one other thing that will only make any camshaft come to full life.Not to is shooting yourself in the foot.And with those there are many other small things that will also help out.Reducing friction anywhere at all possible!This goes for your entire bike.When anytime I'm not running a cartridge bearing.I always clean the bearings and polish out the area or race the bearing will ride upon.To a mirror finnish wheels and bottom bracket.After I use a tire that will handle high pressure PSI.Sure they ride like a rock but a lot less effort overall period.At times the difference between dying while riding to almost effortless.And I keep the weight down.Without getting all insane about it.Point here being using titatium fasteners.Only a flow blown crazy person will care to believe in having to use them on anything but a aircraft.When there are not enough fasteners on a bicycle to make the difference.Along in the fact titanium will snap like a cracker anytime at all with any real force.There light and that's about it.On a bicycle very few areas would I at all dare use one of those.Id sooner buy aluminum and stainless.And that is exactly what I do use on a bicycle on engines.It all depends on where and what.But theres four choices.Ether grade eight or ARP for all internal rotoating parts.After for all that do not move and afew that do but haven't the stress.I use all stainless and allenheads.When there overall a grade 5 and that's not bad and still more than enough for all covers without question.Plus stainless is lighter than regular steel.And it wont rust,if you think it does think better and again.The only tghing stainless will do is look as if its rusting.When it simply picked up the color from one next to it that is rusting.Some 0000 steel wool will clean right off.Just like it will clean up any chrome very nicely.And remove rust from a blued gun.IF the rust is surface and not been there for long.Use it with hoppies not dry .The same should be done when polishing any bearing race or area that has to be uniform and with a tolerance.I only use a hard polishing bonnet with the white polishing compound.Which is the least abrasive of them all.No sand paper nothing.When on aluminum and a wheel race that's all you will need.Stell requires more and real attention.I know from years of working with all various metals.And types of work.When I also do different types of metal art.And I do sculpt and have in steel aluminum wood and antler.Copper and brass.So I know what I'm talking about.Anyone that really knows me.Will quickly say.He speaks based on fact.So if he doesn't know he wont say or say he doesn't know.So for as much as it may seem I know.Trust me theres a lot more I don't know.As far as cubic inch engines go.Dont ever think displacement will take any engine in less.Because until you get into mountain motors.IT just is not at all the case.Even then just about any well done super charged or twin turbo setup will smoke most larger engines.With the right setup else where it can be amazing.And it wont matter what type of machine it is.OR what its doing.Bottom line is its all in how well its setup for its use.Right now I have to give this to the guy with the 212cc engine okDo to the price and work to get a 79cc close enough in a simple race.Isnt at all worth what youd go through on a smaller engine.When often there the same exact price.And what works best for YOU!
 
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MotorBicycleRacing said:
Yep, those walls of rambling text are unreadable.

No white space and PARAGRAPHS. Hit the damn Enter key. :D

I doubt if anyone read what he wrote....... .duh.
Click to expand...

I tried, but broken sentences, no spaces between sentences, and very poor paragraph structure made it extremely difficult to decipher. I'm trying to get that power out of my 79cc bike, as I actually have gears I can utilize for cooling and high speeds, but while engineman seems to be the one guy who can help me the most, I can't read hardly anything he says. I will be shaving my cylinder head precisely .026" using a sheet of acrylic, 320 grit wet or dry sandpaper with TapMagic machine oil, and a guide line given by a feeler gauge and a fine tip sharpie pen. I still have to get springs, a reworked carb, a flywheel, an alternator (one of the main reasons I'm doing the extensive performance mods), a camshaft (from what engineman says), pushrods, and all the DMV crap that our government is making us do. I will not be getting a manifold for a larger carb cause i want to maintain the 80mpg i have as much as possible, AND I want to keep my great air filter, which has a shock cone built in (requires more fuel because its a 90* filter facing forward, so RAM AIR, HAHA!). I should revive my post honestly, particularly after I get the thing rebuilt after the paint I put on it.
 
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