My 3kj Project

cahitapower

Well-Known Member
Hey...i just joined this website in search for help with my Project. I am working on my scooter which is a Yamaha Jog NextZone. I've swapped out the old 50cc motor and replaced it with a bigger 90cc motor(from a yamaha Axis). I just put new covers on it as well as rims and a Jayaco Muffler. I don't know much and when i try to search for parts everything seems to be in a different language, so I'm kinda clueless on were to find performance parts for it....hoping someone can guide me on find parts...

Here on some pics of my Jog 3kj...

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what exactly is it you're looking for as far as performance is concerned? if you're looking for a race build the 50cc 3KJ engine has a lot more tuning potential than the 82cc 4DM engine as tuning parts from Europe are plenty & more advanced than what they can make in Taiwan & Japan & is faster than even a 132cc monster stroker engine setup for a 4VP 100cc engine.

if you're looking to build a cruiser the 4DM 82cc is a good engine to build on & you can even punch it out to 100+cc with a 54mm kit & 47.6mm crank from the BWS100 engine.

where do you come from?
 
well i live in U.S but my scooter is in Dominican Republic which i go often....how is a 50cc better then the engine i have now which is an 90cc...as for parts, i want to start by looking for a clutch, prefer full race...
 
well i live in U.S but my scooter is in Dominican Republic which i go often....how is a 50cc better then the engine i have now which is an 90cc...as for parts, i want to start by looking for a clutch, prefer full race...

the 50cc block is better because there are real race parts available for that block, 70cc kits, 78cc kits, 86cc kits and 90cc kits. there are no real race parts made for your 90cc block. if you check out the other projects on this forum you will the race kits i am talking about.
 
well i live in U.S but my scooter is in Dominican Republic which i go often....how is a 50cc better then the engine i have now which is an 90cc...as for parts, i want to start by looking for a clutch, prefer full race...

like Rydah said there is no real race parts made for the Jog 90cc engine, you can buy taiwan made race parts fro it but it will still get beaten by a well tuned Jog 50cc engine with MHR Team 70/77cc, 2Fast 78/86cc race part. we have raced against Jog90 engine with 112cc displacement & still kicked their ass with a 2Fast4Race 78cc engine, even the Honda Dio 125cc strokers got beat with this setup.

just use the Jog90 engine for daily use & commuting, taht is what it's good for but use the Jog50 engine as a platform to build a serious high hp high revving 70/78/86cc big bore race engines like the MHR, 2Fast & TCR parts.

just look around what parts are being used by the quickest & fastest scooters in Europe, however buying these parts will not automatically make you the fastest if you don't know how to modify, assemble & tune the crankcase & tuning parts for more power. those kits we told about are really good out of the box, all you need is to prepare the crankcase for the parts you'll be buying.
 
Rydah1 i believe that as well...i've gone threw countless pages on google search and seen so many crazy parts that i would have never seen in DR...i would really love to switch my air cooled cylinder to a water cooled system, could this be possible on my 3kj engine?...also before i sold my 50cc(yea i know im a dum ass for doing that now >:I) there were alot of parts that could be interchangeable from the 50cc to the 90cc besides the crank and the cylinder/piston...i could use everything else on it, my point is if there is so many performance parts for the 50cc wouldnt it go for the same as for the 90cc?....

ps..thanks alot you guys for the help
 
Rydah1 i believe that as well...i've gone threw countless pages on google search and seen so many crazy parts that i would have never seen in DR...i would really love to switch my air cooled cylinder to a water cooled system, could this be possible on my 3kj engine?...also before i sold my 50cc(yea i know im a dum ass for doing that now >:I) there were alot of parts that could be interchangeable from the 50cc to the 90cc besides the crank and the cylinder/piston...i could use everything else on it, my point is if there is so many performance parts for the 50cc wouldnt it go for the same as for the 90cc?....

ps..thanks alot you guys for the help

now that is a bone head move in your part (j/k) you should have never sold the 3KJ engine.

i have MHR Team & 2Fast race parts in our Yamaha Jog 3KJ engines & they are all water cooled, find all my old posts & you'll see our drag scooters.

allow me to post pics of our dragscooters here.

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the problem with the 4DM 90cc is it's internal crankcase design, you can't run anything less than a 2Fast 78/86cc, TCR 80/90cc or a Malossi MHR 86cc bcoz the crankcase volume will be too much for the 70cc setup, it won't run well at all.

another thing would be the gearing, there aren't many gear kits available for the Jog90 except for those that are made in taiwan plus it is very hard to find a magnesium wheel for the Jog90 rear axle, KOSO only made magnesium wheels for the Jog 50 which is on my photos.

maybe you could try to locate your old engine & buy it back or just find another 3KJ engine.
 
Wow thats Crazy Tiba!!...i was just reading up on your build on another website(stalkerzone)...lol guess that goes to show you how small the net is,haha..

your build is sweet!...im learning alot from your build thread, i dont even know the names of a few parts but your thread has it all in there :)... as far as a 4DM engine i have no idea was is that :/ i swaped my original 3kj and what i have now is a 3WF (thats what it says on the case)...so im kinda lost in that part

Also i read on the other site that you have a performance shop..do you sell parts? maybe you could help me out in picking parts and guide me through to build a mean engine..
 
well its about time i started posting updates on my thread since i'm heading back to my country in about 2weeks from now and will be putting in some work and hopefully i get a pass down the track for the first time,

As far what the scooter got is...., a custom crank made by a Jayco for the 90cc 3wf engine, 101 cylinder bored out(cant remember whats the bore on it right now |(), transmission gears from Jayco as well, the ignition was taken from a motocross dirt bike and fitted onto the 3wf engine with a cdi which i cant remember the name of it..(sorry can't remember many thing of my project its been a while but will be posting up pics once i get there)

so far i have bout,
Yasuni C30 exhaust
stage6 bell
Malossi clutch
Stage6 Reed Valves
Malossi Reed Valves(trying out both of them see what suits me best)

Will post up pics as soon those parts come in...

Now i need some help with the Variator, I was thinking,

A: MHR Overrange kit with the rear clutch parts or
B: Polini Evolution kit(9rollers)

Any idea which is best?

 
the C30 only works best with a highly tuned 70cc kit like the MHR Team 7T, i don't have any high expectation that the C30 will ever work on a 90cc setup like the one you're building, simply put your engine won't ever see 14K rpms especially with those Jayco stuff.

for the transmission i prefer the Polini Evo SS9 for the vario kit & Malossi overrange rear pulley, for drag racing the Delta clutch is better coupled with a Malossi wing bell.
 
thanks for the tips tiba, your like the only active member on here lol and i would like to thank you for it , lets see what happens when i start rebuilding and most likely i will be changing the set up on my internals but i wont be giving up on the 3wf engine.. :p
 
thanks for the tips tiba, your like the only active member on here lol and i would like to thank you for it , lets see what happens when i start rebuilding and most likely i will be changing the set up on my internals but i wont be giving up on the 3wf engine.. :p

you're fighting a losing battle though, wasted time & effort, just to give you an idea look at the 2Fast TCR Polini Big Evo 78-94cc kits & exhausts. you'll have an idea why big cylinders have big port areas & big exhausts.

it would have been better if you just got a Polini Big Evo kit crank & exhaust, it'll probably fit the 3WF crankcase with minor modifications.
 
i see what you mean, but i think that the crank i got now its pretty good size mm for the casing and i highly dough that any of those kits has a bigger bore then what i got on now. The piston was taken from a 125cc motorcycle and fitted in with a coating they gave the cylinder to keep it cool. I'm not trying to build it with the stock 90cc bore. And the ports were opened up aswell but i cant remember right now. But once i get there(next Friday)i will get the solid info...i will talk with my friend that has been helping me out with the build.

i will take your advice on the crank, i will look at the size of the polini crank and compare it to the one i got on now. if you know the size that would be great!!...

thanks
 
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