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  #11  
Old 02-21-2017, 11:32 AM
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sportscarpat sportscarpat is offline
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Default Re: Performance head for 99cc/79cc predator

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.
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  #12  
Old 02-22-2017, 11:51 AM
engineman engineman is offline
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Default Re: Performance head for 99cc/79cc predator

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.
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  #13  
Old 02-22-2017, 12:07 PM
engineman engineman is offline
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Default Re: Performance head for 99cc/79cc predator

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.
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  #14  
Old 02-22-2017, 01:02 PM
engineman engineman is offline
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Default Re: Performance head for 99cc/79cc predator

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.
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  #15  
Old 02-22-2017, 03:45 PM
engineman engineman is offline
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Default 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!

Last edited by engineman; 02-22-2017 at 03:54 PM.
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  #16  
Old 02-22-2017, 05:36 PM
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culvercityclassic culvercityclassic is offline
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Default Re: Performance head for 99cc/79cc predator

I fell a sleep after reading a few lines of your excessive post today...can you sum it up in a few sentences please...
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  #17  
Old 02-22-2017, 06:33 PM
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MotorBicycleRacing MotorBicycleRacing is offline
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Default Re: Performance head for 99cc/79cc predator

Quote:
Originally Posted by culvercityclassic View Post
I fell a sleep after reading a few lines of your excessive post today...can you sum it up in a few sentences please...
Yep, those walls of rambling text are unreadable.

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

I doubt if anyone read what he wrote.......
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