Looking to buy first bike engine kit and i need help deciding which is the best?

Discussion in 'Motorized Bicycle General Discussion' started by kno3body, Jun 9, 2014.

  1. kno3body

    kno3body New Member

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    Okay, so im new here and apologize in advance if im posting on the wrong part of the forum. I'm 5'7" and weigh about 160lbs. Im also i speed demon. Im looking for an engine kit from a reliable company that can offer me support and parts when i need it. I'll be riding it as my main mode of transportation (30+ miles a day) and would like to be able to go over 40mph. I'm currently looking at bikeberry.com's 2 stroke Flying Horse performance package which goes for $325 and claims to go 40+mph. I cant find any decent review on it however so im skeptical about throwing my money at it. Sooo, I guess the big question is what do you guys think is the best gas powered motor kit that is both reliable and fast(40+mph)?????????? Please and thanks in advance.
     
  2. mapbike

    mapbike Active Member

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    Personally I like the engines that are sold by thatsdax.com and by another fellow member here Neil Senior aka: (Motorbicycleracing) this is his forum name.

    Sax calls his the Gen IV and Neil reffers to his as the Gen V, these are better than average engines in my opinion and experience, better balanced cranks and better main crank bearings, the rest is typical china girl stuff that needs some deburring and TLC to get it all just right.

    Now one thing you should understand is that although these engines I have referred to here are capable of pushing an easy rolling well built bike down the road at 40 MPH, that honestly all depends on several things, if you are looking for reliability out of one of these little engines realistically you should be thinking, a well built bike that can cruise in the low to mid 30's, the gearing is critical and the terrain you plan to ride on is also a factor, if you have hills where you plan to ride then you will need to gear the bike for those conditions, having a well tune carb and an exhaust modified to breathe better than the stock pipe is also needed for good power and torque, I have bikes that will cruise nice at 40+ MPH pulling me at 215 lbs, but they engines have some internal work done to them, example: port work that isnt complicated to do if you have the tools and know how, but if you run one of these engine 40+ mph for 30 miles you may or may not make it there and back under engine power, they aren't made for that and the amount of rpm's they turn at those speeds will wear the little gal out pretty quick if you plan it to be a daily rider at those kinda speeds, just aint gonna hold up.

    Now if you build it to have a top speed in the 40 MPH range but plan to cruise it at 30-32 MPH with a good quality oil and everything about the engine and bike set up right that is doable and it is possible to have a fairly reliable bike this way, but you are talking about running one of these things at break neck speeds that they just wont hold up to but for so long, I run mine pretty hard at times but not for more than 6-7 miles at a time and then I do most of my riding in the low to mid 30's.

    you will get many opinions here along with the ones I just gave, I give mine based on my personal experiences since I got into this hobby in 2009 when I built my first bike that still runs good with several thousand miles on it.

    Dax is out of his GenIV kits right now looks like but you can PM Neil (motorbicycleracing) and he can most likely get you fixed up, he's a knowledgeable fella and he takes care of his customers as much as he can, he doesn't do pay pal but can quickly tell you how you can get what you need and he will get it shipped out to you asap, he's an honest man and I prefer the type engines he sells over all the other I have used, smoother, better power and fastest china girl engines I have had so far.

    Map
     
  3. Davezilla

    Davezilla New Member

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    I agree... Dax and Neil sell some of the best China Girl engines out there, they run great stock and can withstand some serious mods... Map has good advise and I'm running a Dax Gen IV in my bike as well. Mine is also highly modified and very dependable. If you're planning on going 40 or above, I'd strongly recommend starting with one of their kits as your base to build up from.
    One word of caution tho is that none of these kits will push you up to 40+ mph without mods and higher gearing. Being that you weigh around 160 pounds you do have an advantage over someone like me that weighs about 220 so you can use a smaller rear sprocket without giving up as much acceleration as I would so a 36 or 32 tooth sprocket will help you get there fairly easy. A good expansion chamber pipe Using a Puch Hi Hi head or Fred head will give you more compression and help keep the engine cool, then using a good oil like Opti2 or Amsoil is the other key to making these things last a long time, but like mentioned above, keep the high speed runs limited and cruise it in the low 30's and it'll last plenty good.
     
    #3 Davezilla, Jun 9, 2014
    Last edited: Jun 9, 2014
  4. crassius

    crassius Well-Known Member

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    more depends on the builder than the kit
     
  5. mapbike

    mapbike Active Member

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    There is some truth to this statement, but I have kits that I have done good solid mods to that because of a badly balanced and untrue crank you are very limited to what you can get out of them, but on the other hand, if you start off with a better foundation like a dax or Neil engine, even in its stock unmodified form it will run smoother and out perform a badly balanced engine that may have a the right things done to it but has such out of wack internals mainly the crankshaft that it will vibrate itself out of any performance ability.

    But yes top performance will depend on what is done to the engine even if it is a good platform to begin with, things have to be done right even to a good engine that has a lot of potential.

    Map

    A solid engine with a good crank is the key to a good build... and I know this to be a fact and is why
     
  6. maniac57

    maniac57 Old, Fat, and still faster than you

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    I really like my GenV from MotorBicycleRacing. Much nicer overall quality with the upgraded hardware and better balanced crank.
    I got nothing but good customer service and would not hesitate to buy another.
    Keep in mind, ANY engine will die under abuse so don't be too surprised if you find yourself replacing motors quite often.
    From the sound of your post, I suspect you are going to be breaking a lot of stuff.
    Honestly? If you really want to do 40+ all day long, you might be better off with a custom build with the parts to handle abuse. Better brakes, stronger frame, bigger engine, etc. are about the only way you are going to get the speed you want with any chance at reliability.
     
  7. Davezilla

    Davezilla New Member

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    I have to agree with Map on this as well... I've bought cheaper kits off ebay and spent more time truing the cranks on the lathe, installing the good bearings, cleaning and de burring etc just to get them to run smooth and reliable... They did really nice once the extra work was done, but if someone was to just bolt on and go, the engine may vibrate badly or kill the bearings in short order, some have been lucky and had one last really good without doing all the extra work, but most end up disapointed.
    For me, it's so much quicker to buy a good bottom end that's already nice and true with good bearings already installed and very little prep work needed to get up and running. I can take a Dax bottom end right out of the box, install a cylinder and piston setup to it, bolt it onto my bike and go without worrying if it's going to shake it's self to death or eat a bearing after about 10 hours of run time, the other kits I've got off ebay from different sellers almost always needed major crank work just to get them true, then need to be re balanced and in some cases, the bearings were already turning rough or had play in them. One engine I had there was about 1/8" of side to side play at the crank and wouldn't have lasted more than a few miles if I didn't catch the problem and correct it.
     
  8. Davezilla

    Davezilla New Member

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    I also agree with Manic because if you plan on running 40+ all day every day, the engine won't last very long, you can set it up to run better and last longer but running these at full throttle all the time just isn't good for any engine.
    If you want to go that fast all the time, you should consider buying that Morini clone off Dax's page or get a KTM clone and gear it so it'll cruise at 40, it'll cost you about 3x the price of a China Girl but it's also built better and will last longer if not ran at WOT constantly, but will also let you go around 40 or so without having to be at WOT.
     
  9. rogergendron1

    rogergendron1 New Member

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    Peraonally i would go qith a grubee gt5

    Its a 38mm stroke but it has the same full circle crank as the dax ballanced bottom does it just has the big end pin drilled for 38mm instead of 40 mm

    it comes with a larger bore and longer intake than the dax 16mm bore and 6in long vs dax 13mm bore and 3in long so u will get better flow of the bat and the steel intake has a larger flange with thick weld making it port match to the jug a whole **** of a lot better than the little flange on the dax does

    it comes with a fuly tunable cns carb with a high flow filter, this carb is larger than the dax nt carb and for me at least it tunes easy and it has a noticably better low end and throttle responce , i actually tos the dax intake and carb in the junk pile and swap to the long z and cns when i buy a dax kit

    other than that all the ht motors are pretty much the same

    but thats why i buy grubee gt5s cause i get a better intake and carb with larger bores and better flow and i find the 38mm stroke likes high rpms and takes mods like high roofed and large exhaust durations better

    but if your just looking for a stock put put and dont give a crap i will tell you to contact motorbicycleraceing a member here and get a gen v motor kit he suplies you with a 40t rear sprocket and that is a hug big deal and is how the motor should be geared for a 26in wheel

    his gen v kits are the top of the top if you want a good running kit geared right from the start. They take mods like high compression and handle high rpms and they dont vibe as mutch as others do
     
    #9 rogergendron1, Jun 9, 2014
    Last edited: Jun 9, 2014
  10. rogergendron1

    rogergendron1 New Member

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    But yeh if you want a kit that will out last the bike its on

    buy a gen v and strip it down to the bare case halfs and then stuff the crank bearing bosses then reasemble it with the juice motoparts kit with high qual bearings and copper gaskets
    also remove the crank end play with shims i used 6 shims to get rid of my end play on my current build by taking them from other scrap motors i had but knowing my crank wont slap around in the case and knowing i have good bearings and a well balanced crank means the bottom end will last the life of the bike and the motor will only require a piston ring and jug swap every 2500 miles or so

    No matter what kit you gwt i would order the puch 70cc hi hi head at the same time though you will apretiate the extra cooling and all around power it gives , the huge cooling fins will help the motor last longer by leting it run cooler and the higher comp gives a needed boost in power and its only 35 bucks to your door

    trust me on this one lol the last two dax kits i ordered had heads with verry poor castins and plug threads were so bad i couldnt even ise one of them! nothing P O s u more than getting a kit and not even being able to set it up for a customer cause the head is junk out the box and having to do a high compression upgrade for free for them and trying to explain why !!!! Then they like you though cause they get a big ol high comp head for free but it does cut into my build time and money! !!!

    Does this mean i dont like dax? no i love dax motors i just got the luck of the draw on two motors . . . It happens thease things are from china and are made in a toy factory

    will i buy dax again heck yes and probably for my next customer and if the head that comes with that kit is junk to well i guess they get a puch hi comp upgrade for free and i will probaby have to wright a letter to dax pointing out the bad head castings and plug threads but as of now i chalk it up to the luck of the draw
     
    #10 rogergendron1, Jun 9, 2014
    Last edited: Jun 9, 2014
  11. Davezilla

    Davezilla New Member

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    Doesn't the GT5 have larger intake and exhaust ports? I thought I read somewhere that their ports were wider than the PK80/F80...
     
  12. rogergendron1

    rogergendron1 New Member

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    Oh and if you want to do 40 and not have your motor crap oit on ypu in a real hurry lol

    plan to do some port work . . . Nothing major and nothing that takes any real thinking jus a good clean up and finninsh on the intake and exhaust the mark your piston skirt on the intake side at top dead center and cut that part of in a half circle shape then port match everything and be shure to get your carb tunned in

    run a 40 t rear sprocket and you should see close to 40 without OVER stressing the motor

    you should get a cruise speed of 35 at a decent rpm of 7500 - 8000 stiil high but nothing compared to what it would have to turn with a 44
     
  13. rogergendron1

    rogergendron1 New Member

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    Yes the gt5a has 40mm intake spaced bolt pattern
    the gt5 is almost the same size though it has the standard bolt spacing but the actuall port is about 1mm wider on each side from what i have personally measured so far

    that doesnt mean the gt5a is more powerfull or any better per say cause in orde for you to benifit from the wider port you still need to do a lot of dremal work via port clean up and port matching and since that stuff has to be done anyway . . . Why not just port a standard jug to the target size? so for me its nothing more than a little bit of saved time porting and if your not going to port you wont even notice a differance between the 30 and 40mm intakes
     
  14. rogergendron1

    rogergendron1 New Member

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    I just realy do not like seeing newbies get shafted by buying an ebay kit thats all out of whack lol, woth the old style 3piece crank and con rods with no oil holes and a jug with casting flash so bad it flakes of and destroys the jug and a head that cant even seal the plug

    so i recomend they spend the extra money and order a dax lower and top end unasembled and then clean it up inspect it and put it togethwr them selves and learn about the motor wile doing it and i recomend you all buy the punch head even if you dont get the high comp one simply because it will cool the motor properly and seal right and the plig threads wont leak and it has a proper squish band

    its worth the 35 bucks all day and night

    so when this question is asked i say buy a dissasembled dax and put it together youdself and mod as u see fit so you can learn about the motor and be proud of it when your done and not to mention it will run btter and pull harder too

    dax or gen v doent matter and if you really want to lear order it dissasembled bottom end and top end seperate
     
    #14 rogergendron1, Jun 9, 2014
    Last edited: Jun 10, 2014
  15. mapbike

    mapbike Active Member

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    Ditto..........!
     
  16. Davezilla

    Davezilla New Member

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    I fully agree as well... There are so many sellers of these kits it's mind blowing on ebay alone... and everyone is claiming theirs is better in some way or faster than the other kits when they all come from the same place... they just buy them in bulk from the lowest price suppliers and then ship them out without ever opening the box to see what's inside. Then since most people leave positive feedback before they actually install and run these, they look golden to new potential buyers with very few negative feedbacks for bad engines.

    With that being said, there are a few that do check their products to make sure they're up to standards, and some even swap out the hardware and bearings so your new engine will last more than a few rides up the street.

    if you prefer the PK80/F80 type engines, Dax or Neil are teh guys to buy from, there are others but I can't think of who they are off the top of my head right now, but you really can't go wrong with either of them. If you want the GT5 or GT5a type, there are sites that sell these including Grubee's site, these engines are slightly different and some parts don't interchange with the rest of the China Girls, but as mentioned above, those who run them really really like them.

    I don't run any of these without taking it apart and checking that everything is up to the task, but I gotta say it's nice to be able to buy a Dax bottom end and not have to do that, I can pretty much just add my performance parts and go...

    The reason I was asking about teh GT5 cylinders and their port size was because if they are actually bigger, they would save a little porting time, but I can cut out 1mm or so pretty fast with the tools I got here so it's not really that big of a time saver. I do however, take any new jug and check all the ports for plating overhanging because if not cleaned up and chamfered it will start to flake off in those areas and the engine will fail in short order if a ring snags on teh excess plating or if it starts flaking off because once it starts it's pretty much game over for that cylinder, and it's a lot cheaper to just replace one than it would be to have one replated.

    I can also agree about buying just the bottom end from Dax and building it up from there so you can learn these things better, or if you're already a good mechanic, it's an easy way to save a few buks, it's ALWAYS a good idea to at least pull the cylinder off and check the ports for excess plating overhanging into the ports because this is a failure point because in short time the plating will begin to peel back in these areas and the fix is as easy as filing or carefully dremeling the plating to match the port openings, then finish the job by chamfering the openings for a smooth surface for the rings to pass over... Opening up the ports is a sure way to get better performance as long as you don't go too wide or too high on the exhaust side or too low on the intake side. Cutting ramps into the piston crown at the transfers and exhaust also help, and so does cutting off about 5mm from the bottom of the skirt on the intake side, don't worry too much about the port being partially closed at BDC because if you open it all the way by cutting off more from the bottom of the piston skirt, the intake duration will be too high and you'll lose a lot of low end power, but there's a lot more on porting to read up on before grabbing the dremel and letting er rip, and I wouldn't recommend doing it if you've never done it before without asking a lot of questions and reading up on it first, there's a lot to gain by doing it right, and a lot to lose by cutting out too much...
     
  17. crassius

    crassius Well-Known Member

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    I suppose it may also depend on the modifications done to the motor, and whether they help or hurt. I get the cheapest I can find, then leave them alone. Haven't seen the older, unbalanced cranks in the last year or so, but maybe that is a US thing that is different in other places.
     
  18. kno3body

    kno3body New Member

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    So from what i've gathered so far nobody seems to even care about the bikeberry.com performance 66cc engine kit, right? Im just gonna assume its a p.o.s.? So if i were to get a dax bottom end and puch hi hi head you guys would say that it would be both reliable and fast? Which mods would you guys suggest to add for extra power? I appreciate all the info.
     
  19. rogergendron1

    rogergendron1 New Member

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    I believe bike berry has grubee but dont hold me to it lol

    i ordered all my gt5s through custommotoredbicycles.com they even had the gt5a jug with the large intake port and sold gt5 bottom ends but i have so mutch gt5 stuff now i havent been to the site to see if they offer the kit still however i do know for a fact that they have all the differant pistons and even sell bolth the 110 and 115mm bottom ends and con rods and the pistons for them allong with various differant style jugs so its a good place to plan a build using your own creativity with the parts
     
  20. rogergendron1

    rogergendron1 New Member

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    A dax with a good port clean up and port match with a puch head is the base for all my customers builds and yes its about as powerful and reliable as you can possably get for that amount of money anywhere period

    if your looking for a grubeegt5 its the only kit that comes with the long steel intake and cns carb on the marker i know of and those two things allone make it worth it if you know for shure thats what u are getting
     
    #20 rogergendron1, Jun 10, 2014
    Last edited: Jun 10, 2014

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