GEN IV dax build and review

my dax balanced bottom end and f80 top end came in the mail today !

this thread will be dedicated to the build of the motor ... piston mods IE skirt cutting and dome ramping, porting and polishing and also port matching, jug decking for squish clearance and high comp head installation, carb and intake install and tunning, and a general overview of the motor and the quality of the parts themselves.

so far i have unboxed everything and looked over the parts and to my suprize everything looks better than the average china girl ! all the castings are vceryy good ! the ports are well casted and the transfer ports have a better shape and designe than the grubee gt5 i have running now, they are angled tords the center and are also wider !

one interesting thing i found was the gaskets, the standard grubee gt5 head gasket is .75mm thick and the one included in the kit is .45mm so right away the dax motor has a thinner head gasket and would offer higher comp given all else was the same. the base gasket is made from 1.6mm thick gasket material it seems to be .6mm thicker than stock so this would tell me that the transfer ports and intake would be raised up .6mm more than a grubee gt5 and offer better port timing and a longer duration.

i do however NOT like the dax head designe, it has a verry thick gasket surface and a small squish band and the chamber casting seems sub par, though the gasket surface is thick it seems the chamber sits lower in the casting leaving it in sutch a maner that when it is milled or decked you can gain more compression from the same amount of work vs a grubee head. having the chamber sit lower in the casting offers more room to machine a better chamber designe or mill for compression. it just needs to be decked down to 6cc then polished clean for better combustion and i will probably sell it as i am using a puch 70cc hi hi head.

all i have done so far is mock assemble it and mark the piston with marker for cutting and moding, and make shure all the parts are correct.

the only gripe i have is that it came with the bottom mounting stud bent but no big deal i waas going to remove them and use bolts anyway.

lots of pics to come should be home from work at around 10:30 tonight to load them up on the site

good review and LOTS of pics to come !

ok here is the unboxing .

so far the only problem is a bent motor mount stud but ehhh not worried gona use bolts and a custom mount any way.

had to take all the covers off and check up on all the bolts and case bolts some needed a lil tightning but nothing to big a deal . everything looks good and its well packed !

here are pics of the piston the head and the port.

i plan on doing a full port and polish, nothing major or crazy but i am going to widen and open up the ports.

the piston will be ramped and skirt cut and a titainium wrist pin installed.

if one were to run the stock motor without cleaning or porting the intake and exhaust i think they would find they have a well timed and strong motor the only complaint is that the suplied intake has way to small inner diamiter and i will have to use the offsett z intake from my grubee as it is nearly 2mm wider in diamiter.

as you can see the transfer ports are way better than that of the standard grubee gt5, they are a bit larger and the casting is far more cleaner, most of all the ports are correctly angled twords the center of the jug ! all i will do here is clean them up and remove the small casting flash at the opening to the cylinder.

the intake manifold however is way tooo small and requires to much grinding to get a real port match so i will use the long offset z intake i have because its already port matched perfectly and is 2 or more mm wider !

the jug to head gasket surface will be decked down for a proper squish clearance and for a better mating surface.

ok here is inside the case and the clutch disk looks to be made of a much higher quality steel than the grubee motors soft plain steel one, all else looks in order !

the piston marked up for ramping and cutting

port measurments with a vernia caliper to come ...

some gaskest measure ments

as you can see the grubee gt5 head gasket is .75mm or more but the dax is only .45mm so a small gain in comp there

the base gasket is 1.6mm taller than the grubee gt5 this puts the transfers more than a half mm taller leading to a greater opening and more fuel in the chamber. and with the taller base gasket i can safly runn no head gasket after surfaceing the jug and head smooth.

more measure ments for those with interest. all are of the stock motor intake and exhaust

as you see even though the bolt pattern is bigger for the exhaust port the port onpening is nearly the same .

i believe i can and will take .5mm off each side of each port and 1mm off the bottom of the intake and 1 mm off the top of the exhaust and clean up the whole port for flow, a nice brushed finninsh

bolth stock ports are 24mm wide and 15mm tall average. i believe good flow and all around power can be achieved with the ports bolth widend to 26mm wide and 16.5 to 17mm tall i will start at 25mm and 16mm though and see if i need to ad to that when i make a 1in diammiter intake, i believe the motor can not flow enough though the small stock intake for a larger port to matter so much, so big old ports wont benifit if you still have a stock intake manifold

ok i plan on removing 6mm or so from the entire intake side of the piston skirt as i have had spectacular results doing so with the gt5 motor ..... removed 1/4inch

the stock piston only covers 3-4mm of the intake port and i will be opening the port some so i will need to remove acordingly and i also would like a bit more duration than that so an extra 1mm will be in order to hold it open a lil longer.

6mm cut will hold the port open quite a bit longer than stock and allow a lot more fuel into the case and cutting it off the whole skirt will help lighten the top end along with the titainium pin

the ramps will be about 25mm wide and roll up to half way to the center of the piston, they will go down to within .75mm of the top ring

ok here is what i mean ... the pencil mark is what the part of the piston actually protrudes into the port, what i am removing is the line cut 1mm above it in the red dikem all the way across the skirt. so this will allow the port to open all the way and then hold open for another 1mm of piston travel and the piston will be lighter due to the amount of material removed.
i have had supurb results with this mod !!!

ok i am off to port the jug and will check back tomorrow.

ok i have been up for quite a wile doing some mods that i have down pat with thease motors. mods i know for a fact get me to where i want to be ... lighter top end faster rev's and and a strong power band in the mid to upper rpm range, that being from 5,000 to 10,000 rpms . and i will gear acordingly ie 40t rear should bring me to 35 to 40mph cruise and a 45mph top speed. anything under 5,000 rpms or like 25 mph i pull the clutch in slow down and pedal if i need to go slow.

any way here are the first mods !!!

first i did the ports .... stock opening for the intake was 23mm wide and 15.5mm tall, and stock opening for the exhaust was 15.75mm tall and 24.25mm wide, they are now 25mm wide and 16.25mm tall for the intake and 16.80mm tall and 26.25mm wide for the exhaust

i lowered the intake 1.25mm and widened it 2mm
the exhaust port was raised 1mm and widened it 2mm

-so stock intake port 23mm wide 15.5mm tall
-new intake port 25mm wide and 16.25mm tall


-stock exhaust port was 24.25 wide and 15.75 tall
-new exhaust port is 26.25mm wide and 16.80 tall


first i did the port matching of the intake manifold i did the best i could and it machest the port perfect ... however i am suspect that the actual diamiter of the maniflod intake is too small and i may use a custom one or on from jnm motors

dont know if you can tell from the ginormous pile of aluminum shavings lol but i took quite a bit off, in fact if i take any more of off anything it will blow though the port walls !! i did however maintain the port shape as best i could wile rounding them out a bit more.

i also made some buco huge ramps in the piston to help out with port duration and timing !!!

i also took 7mm off the entire intake side piston skirt it stays open for 1mm piston travel after TDC ! perfect !!!

my next mods will be to mock assemble the motor and measure the squish on this motor with the puch head it seems the piston is the same dome shape as the gt5 so i may have to take a mm or so off the jug

then i am going with a tunned length of 1in diamiter strait pipe and a custom made flange for an exhaust, it will be tunned for 5,000 rpms for the begining of the scavaging effect and will end around the max rpms

i will run this untill i can get my girl to weld me another tunned x chamber

fuel will be ether 1st choise of true fuel ethanol free 92 oct 40:1 mix
or
opti 2 mixed 1 packet to .6 gal of 93 oct for a mix of like 35:1 or something

buying a 4 ft 1 in aluminum tube and 1/4 thick 2in wide plate tommorow and making up some long custom intake manifolds that are matched to the standard ports. will probably sell them dirt cheap as in just cover the shipping and they are yours lol

the intakes will have a 1/4 in thick flange that is port matched and be made from 1 in tubing welded to the flange the inner diamiter of the tubing is 7/8 ID so it will be a great deal larger than stock. at the end of the manifold my girl will weld on a reducer if need be to fit the standard CNS or Dellorto carb, ether that or i will use tubing that just fits in the carb mount and has the thinnst sidewalls possable. if i go that way the intake wil have a 5/8ths ID or so and still flow WAY better than stock ! also there will be a smooth bend in the tube and not a turbulance causing sharp corner. they will be 6in long and offset to the side of the frame like the z manifold but with long smooth bends and a mutch wider intake .

if i have to buy 4ft might as well make a bunch and get rid of them at cost right ? i might be using a 21 mm mikuni carb i have so my manifold will have 2 flanges so it can mount to the carb via the carbs o ring flange. if the 21 mm mikuni will not tune to the motor because of the size of the venturi i will go with the cns v1 and cut the intake manifold so it will clamp on.

i feel the long 6-7 inch intake manifold helps out with low end torque and midrange power, that is what i will need to gain back through propper gearing and lil tricks with this high rpm high power band motor i am building.

ok i have it all together with the puch head on and i was suprized to find that after the port and polish and piston ramping that at BDC the exhaust port is fully exposed and the transfer ports are fully exposed to the rim of the ramp ! the ramps worked out perfect fo the transfers and will give a lil more duration to the exhaust. the puch hi hi head is on with one thin .40mm gasket and it has LOADS of compression !

cant wait to get it up and running ! i will have to wait till monday though as i am going up to maine tonight and wont be back till then .

ok here it is together and ready for an intake manifold and a custom exhaust !

ok you can see the transfers are all the way open with the ramping

through the exhaust port you can see the piston does not block any of it and the ramp will help flow

the intake is blocked at BDC and at TDC the intake is full open with no blockage and the piston has a full 1mm travel duration !

this would seem to be the nices china girl i have owned ! if this turns out the way i think it will then no more grubee gt5 motors fo me ! the dax is where its at !

On my way to work then to maine more to come on monday ! Monday i set her up in the bike and go for a break in ride. I willl be using the cns v1 carb and a long intake and a free flowing exhaust. Gas will be 93 octaine mixed 25:1 using pro mix full synthetic oil mixed 32:1 with lucas oil upper cylinder lube added to make it 25:1 to help aid the break in

i got the motor mounted in the bike and i am using the shorty aluminum intake till i can make a new one, i got it all mounted up i the bike and ready to go all i need to do is tighten the motor mount bolts and run the chain ! also my cns carb is way too big and i needed to cut the clutch arm cable holder bolt down and sink it into the motor all the way for the float bowl to clear. there is verry little space to work with now and i need that 90 degree filter adapter from SBP.

i am like one of those little yelping dogs that want to pee all over the place its soo exited !