After a lot of talking and research I finally have most of the parts for my 153cc 4 stroke buildup. The crank is done (62mm) and the piston is here (56mm domed) and I will have the cylinder back any day as it has already been bored out and is on its way back to me. Looking for some major wheel snapping power out of this. Oh yeah, gotta 28mm carb for it also.
Check out the pics. The monster will be going together next week.
For those of you who build race quad and bike engines you will probably realize who did the crank work as that is the only company I know of that shrinks rods like that on their strokers.
Oh yeah, that is the 4 speed drum and shift star from Honda so that you don't miss gears because with this much power that will definately break something. I modify the shift stars even further for positive shifts.
This is one of the 120cc 4 stroke engines that I am boring and stroking to 153cc. It will bolt into any 4 stroke pocket bike as it mounts and looks exactly the same as any X12 or X18 engine. No modifications needed, just the engine is about 1/2 inch longer but if you saw the engine it looks just like a 110cc but it is much bigger on the inside and not the outside because it has been punched out.
you should sell these engines, since it is a simple bolt on. I've never seen a motor that big that will bolt on to a 50cc motormount! (I think it would right? 'cause the 50 is the same mount as the 110, and the 110 is the same as yours?)
That would be the ultimate power increase for any midbike!
It's goint to be mated with a 4 spd manual clutch, right?
Yes it will bolt right in and the electronics are the same so it plugs right in also, it is just 1/2 inch longer on the cylinder so as long as you can move your exhaust bracket 1/2 inch forward and you have a 1/2 inch of room in front of your 110 motor it will work and it looks the same so no one will ever know the difference unless you tell them.
I don't think too many people would like the price tag of this buildup. I will give you a hint as to what it costs
Crank-$450 ( you have to have at least 5 done the same way or else it is $1k for just one off crank like this)
Cylinder-$109 plus $65 for the only guy in the world that I trust to bore it out
Piston-$100
Gaskets-$30
Honda shift drum and star= $150
HD valve springs-$25
HD clutch plates and springs-$85
28mm carb with intake=$200
Crower custom ground cam-$150
Head porting and 3 angle valve job-$150
Motor assembly- $250 (that is what I charge for the motor and transmission and to modify the cases to accept this crank but it could be more or less elsewhere)
Zongshen or Lifan big valve engine with wide stud spacing to start with $400
As you can see this build is about $2k and will rip the sprocket right off the rear wheel of a pocket bike and probably rip the swingarm off while twisting the frame. We will put this motor in an X18 and slowly accelarate it up to a top speed with the tallest gearing I can find and should actually get close to 100mph but then the motor is going to be put it into a dirt bike chassis that is already waiting for it.
BartW - You are truly a mad scientist of the the Pocketbike world.
I could not take that kind of credit, these parts were all purchased and modified all over the place, I am nothing more then the guy who is going to put it together and make sure everything clears and works.
It is costing me much less then $2k,
I already had the $400 engine to start with so it brings it down to $1600,
I am doing the work myself so it brings it down to $1350
A DOHC kit is over $3000, plus you have to buy a $300 Honda engine to start with, then have it machined (cases need to be bored out $75) then you have to have someone assemble it ($200-300) then you have to buy the carb kit ($200) then you have to buy a transmission that will hold up as the stock Honda one will not ($750 for the Red Baron or $1100 for the Takegawa) so it ends up being over $5k.
This will make more torque then a DOHC 124 and be very close or equal to in HP for a fraction of the price.
looks real interesting and cant wait to see it all finished up and done......i have a 120cc lifan that i am putting into my x18 and i would deffinatly like to mod the motor....i was planning port work which i can take care of my self.....but what i was wondering is what options do i have for cams, would i have to have the stock ground and rewelded or are there aftermarkets avaliable...and i know it is a big valve engine to begin with but are there any 1mm over stainless valves ffor it....and in your opinion do you thnik the stock cylinder can be safely bored to 56mm or is a cylinder change needed?......
The stock aluminum cylinder can be bored to 56mm, that is the absolute maximum I would go as the base of the outside of the skirt is about 58.5 so you are only leaving the skirt 1.25mm thick. I would think that any less then 1mm and you have a good chance of cracking it so at 56mm you may have one small overbore beyond that but it would be questionable as 56mm seems to barely leave adequate room.
The cams are usually the "long cam" and Crower offers the best grind in my opinion in the G2. The G2 is a great cam for midrange and top end while not loosing much on the low end at all, I would call it a great all around cam that can pull to 12krpm if your valve springs are up to it.
For the head work, I have heard of someone actually putting in 3mm oversize titanium valves in one of the monster heads, supposedly after that and their port job it kills Kitaco SE and Takegawa super heads.
I hope you have run a flow bench before if you are going to attempt porting or have some experience doing it. I used to run a flow bench at a shop and saw some really butchered home porting jobs where someone thought that widening and smoothing is porting but had no idea about air velocity, port shapes or anything at all that real porters take into consideration.
If you are considering a 56mm piston overbore, go for it. We have done a few 137s like that and they rip. Problem is finding a piston with a large enough dome for the big valve head's huge combustion chamber. The 56mm I have is a pretty good dome and will be pretty high compression when I am done partly because of the longer stroke on this motor but I won't know what the actual ratio will be till I have everything ready to go and the thinnest head gasket on that will still allow clearance. It is feasible that we may weld up some of the combustion chamber depending on what it ends up with.
You WILL see that bike at K2K, this motor is being built for someone that races there, I will only have it for testing and then it is going right into this person's bike and it will be tearing up K2K and Fremont tracks.
I hope to get some video of it on the track, where you can compare how it pulls on different bikes.
Quote:
Originally Posted by JD-7
tell me that you are NOT going to run that at k2k!remember its all fun and games till someone looses an eye!
Hey bartw I was emailing the guys at faddybike.com and they tell me they have a 160cc engine ready to go.......that is 58mm x 60mm. They also have a few more trick pieces. I am waiting for a response to a couple questions. I will let you know if is is as good as it sounds. In the mean time I am going to sell that NIB "lifan 120 Monster" I have. It is a complete setup for $400 shipped to anywhere in the USA.
Hey bartw I was emailing the guys at faddybike.com and they tell me they have a 160cc engine ready to go.......that is 58mm x 60mm. They also have a few more trick pieces. I am waiting for a response to a couple questions. I will let you know if is is as good as it sounds. In the mean time I am going to sell that NIB "lifan 120 Monster" I have. It is a complete setup for $400 shipped to anywhere in the USA.
DON'T DO IT!!!
That is the place I got that junk 58mm cylinder from, those guys machining standards are so below par it is unreal. I will give you their cylinder right now with the piston for $200 if you want it but I doubt you can use it unless you get another sleeve to put in place of the one they butchered.
The ones I have now were done by someone else, the crank was done by Powroll, the piston is from Malaysia for another application and the cylinder was done by my machinist that I use for all my bore and head work.
The 146 that I had that was all screwed was from that place in Thailand. I got those cylinders from RCM and when it was all screwed up they admitted that they came from Faddybike in Thailand and they recalled the kit as all the cylinders looked like crap.
If I combine the 58mm cylinder I will be at 164cc!!!!
LA sleeve makes a sleeve that will work on these with 58mm bore, but you have to bore the cases as the cases are at 58.5mm so if you bored the stock sleeve to that you will have no skirt left and it is sure to crack.
What a ****in moron 153 cc haha get a real ****ing bike ya queer
You are really smart kid, why don't you spend some time doing something other then worrying about what others are doing with their pocket bikes, obviously simple pocket bikes are beyond the scope of your understanding.
Re: 85+ MPH pocket bike, yeah! my 153cc build 
