stock shorty vs stock long z intake ...

[rogergendron1]

ok i have a conflict with my dax build and i can decide what intake to use.

i have the aluminum shorty and the steel long z offset intake at my desposal

ok here are the facts...

the long z offset intake is about 6in long and has a 16.25 mm inner diamiter and a slightly better port match due to its larger opening

the shortty aluminum intake that comes stock on the dax and others like the pk80 is about 3 in long and has a 13mm inner diamiter and a real small opening that needed srs dremal work to get it to match the port.

i conclude that the longer intake with its 3.25mm larger boar that is size matched to the cns carb will flow easyer than the shorty and due to its length may help add bottom end to the motor due to the volumizing effect beacause of the amount of fuel stored in the manifold between strokes.

long z intake = better flow and bottom end

that does not mean that the shorty is bad or less effective in any way, here is why, first its shorter witch would lead to faster delivery of fuel during higher rpms, second because it has a smaller boar the fuel may be harder to pull though (slightly) but it will go though faster and with more preasure, IE the straw effect ... blow through a huge straw and the wind that comes out has no force to it, to blow the same amount of air through a real thin straw it may require more force but the air coming out the end will exit at a high rate of speed and with mutch more force.

shorty intake smaller diamiter = quicker fuel delivery and faster more forcefull fuel delivery, good top end but may rob some low end due to the extra force required to suck the fuel through the 3.25mm smaller boar.

then again this is all speculation as i have not individualy tested bolth on a well broke in motor under the same circumstances.

what do you all think ? witch would you use ? the z intake has a slightly larger boar than the boar of my carb. carb is 16mm intake is 16.25 there would be no restriction aside from the turbulance caused by the bends in the manifold, if i were to use the shorty, my carbs venturi would be restricted by 3mm but would flow fuel a much faster rate into the motor because its half the length and has only a minor bend that has been smoothed out and it is smaller in diamiter.

what would you use ?

the 13mm boar shorty

or the 16.25mm boar long offset z

the last pic you can physicaly see the differance in boar size.

 

[rogergendron1]

well i forgot to mention there is more to this than the preformance issue here!

i think the stock shorty will look better painted orange carb painted black with a 90deg orange SBP angle air filter on the carb

the long z intake is a plain dull chrome and has visable welds that are not top notch, i would use the standard cns filter. i guess i could sand and paint it also and go for a differant filter....

 

[bairdco]

i've found that the shorter intake, once it's port matched, is better overall.

i'm never concerned with bottom end performance, because the motor revs up so fast it's not really an issue. and if it was, a coupla extra cranks on the pedals would get you through.

i've made longer intakes for clearance issues and always found those bikes to be slower, idle worse, and more prone to stumbling at different points in the rpm range.

my experience has always shown the shorter the intake, the better performance overall.

but since you have both, it's a simple matter to test each one and see what works for you.

 

[rogergendron1]

well i guess i will try out the shorty first, it looks better but its a whole 3.25mm smaller in boar ! i hope the bike benifits in the top end .

but i was also thinking wouldnt a larger boar also benifit top end ? even though the z intake longer it has a 3.25 mm larger boar so wouldnt that cntribute to extra flow and aid the top end ?

 

[rogergendron1]

i decided to break the motor in with the smaller boar shorty and then after its well broken it swap out to the long z intake and report back with the differacne if any, but i will report back soon with how i believe the shorty works in comparison to the long on my old motor during the break in period.

 

[bairdco]

actually, a longer intake should have a smaller diameter pipe. for the same reason you mentioned with blowing thru a straw.

the atomized mixture is forced through a smaller pipe at greater speeds.

i learned this firsthand when i made a minifold from 7/8 handlebars. i had a mikuni carb with a 7/8 spigot clamp so i used some old bars. didnt work well, so i used a smaller pipe with a piece welded on the end to step up to the carb and it worked great.

when the flange is portmatched the speedy mixture will flow into the cylinder unrestricted.

 

[2door]

I've always laughed at those guys who run a tunnel ram intake manifold on a street driven car and wonder why it stumbles and falls on its face at less than 3K rpm. The longer the intake the slower the fuel/air charge is in getting to the combustion chamber. Unless you plan to run WOT most of the time you'll want the intake manifold as short as possible to make the bike behave at lower engine speeds and off idle. Longer intake runs are great for racing, not so much for good street manners.

Tom

 

[rogergendron1]

this is all great info !

i understand about smaller = faster flow greater atomization and quicker reves but 13mm ? that seems tooo small considering i have a carb with a 16mm venturi i would think that the intake boar diamiter should match the carbs venturi boar diamiter to keep flow unrestricted yet even and controlled.

the 13mm shorty seems like its strangling the motor a little bit, i mean come on guys ... its 3mm smaller than my carbs boar !!! w.t.f. am i eve using a 16mm carb for if the manifold is only 13mm ??? lol switching to the 16.25mm ..... the same size as my carbs boar would seem to make more since ! I MEAN the 13mm manifold effectivly makes my carb 13mm, you cant flow air though a 16mm opening if only 13mm of it are actually open lol also the length of the intake is 6 inches witch would seem to be the length that lots of people have gotten good results with wile trying to gain power . its to my understanding that small piston port 2 strokes like a longer intake to a certain extent. and lengthening the intake seems to be a favorite mod on here.

any way i will find out in a few hours when i swap it out and go for a beer run !!! lol

ohh and i do run at 1/2 to WOT 85% of the time so i plan to make this a mid to top end bike with a strong power band

 

[rogergendron1]

what good is having a 16mm carb if the manifold going to the motor only has a 13mm boar ?

wouldnt that restrict the carb to 13mm ? or cause the carb to flow fuel air same as a 13mm would ?

i would think that if you have a 16mm carb, then you would want a 16mm boar intake manifold right ? that would keep the carb flowing the way it was designed all the way to the motor without restriction right ? all i need to worry about with the long z is the turbulance caused by the welded bends and making shure th length is long enough for a preformance gain but not so long it affectsfuel delivery.

 

[Toastyy1990]

You are correct about the 13mm pipe restricting your 16mm carb. The added air velocity from the narrower pipe will lower when it enters the larger diameter carb opening. Also it's spelled 'bore'. Lol a boar is a pig.

 

[bairdco]

although the intake is smaller in diameter, the larger carb will still take in more air and force more fuel thru thru the smaller pipe at a faster rate.

a 16mm intake would be ideal, but as long as the flange is ported to the jug on the 13mm intake it should still give you good performance.

i've read many posts from people about their supposed performance gains with longer intakes, but it's never worked for me, and some of those claims don't seem realistic to me.

my fastest bikes have 1" long modified stock intakes on them.

if i could, i'd mount the carb directly to the jug...

 

[rogergendron1]

i under stand that the best way to mount a carb on virtualy any motor is right to the engine with no manifold or the shortest one possable, in most cases that seems to be what offers the most preformance. like a weed eater carb bolted to the jug. if i could find a carb with a close enough bolt pattern i could bolt it right to the jug or even make a small adapter plate for the 2 bolt patterns, this way the motor has absoloutly no restriction and feeds strait into the motor. but with this piston port 2 stroke china motor it would seem that this is not the case. for whatever reason it seems to want 5-7 inches of a spacific diamiter intake track, especialy with piston mods and porting done . i can not explain why... my theroy is that because its a small piston port 2 stroke the long intake track may hold a charge of fuel between strokes to be fed to the motor sort of like fred power intake plenum. if you look at his manifold you will see that it is just a large empty container of a spacific volume and it acts like the boost bottle theory, holding the blow back charge to prevent remixing and over rich mix when coming of and on the throttle. a long intake track with large boar may have nearly the same internal volume as freds power plenum and act as sutch. where a shorty manifold would allow the charge to blow all the way back through the carb and wast it but have no ill effects, a manifold of just the right lengh will hold the entire volume of the charge and feed it back to the motor. the volume of the manifold would have to be equill or close to the volume of the motor around 60cc for this to work. to the best of my knowlage i calculated the volume of the long z ntake and its just at 28cc half of that, so it would seem that its capable of holding a half the cylinder volume per charge, i am not shure on the volume of freds volumizer intake but it cant be mutch more than 30cc judging by its size and shape so the 2 hold the same amount of fuel air mix.

thats my theory any way lol

so i am swapping out to the larger boar and longer intake right now allong with some other mods and touch up stuff. we will see how it goes tomorow

i painted it up and did a much better port match on the mounting flange and then cleaned up the inside as best i could.

 

[rogergendron1]

Ok my verdict is in ... i put 10 miles on it with the long z intake and there was enough of an over all power increase for me to notice right off the bat. It seems to be mostly in the bottom and midrange and just enough for me to notice nothing extreem. Also most of the four stroking is gone now so it woyld seem to be flowing better too.

I will keep this intake on here untill i get enough money for a reed valve syst