Great motor. Add the SD-HPCARB and you will notice a big difference. you will have to jet it. It is worth it. (Posted on 10/29/2018)

This is an excellent kit. Runs very solid. I have been a motorcycle technician for 20+ years and I can tell that the engine is well balanced. Runs smoother at higher rpm. I would recommend that you at least install the SD-HPCARB. This is a good carb. It makes the motor run quite a bit better and faster and brings out the torque of the engine. Of course the low end speed is a huge difference. you will have to jet the carb much leaner which will cause the engine to be lean at idle and on the slow speed circuit. you will have to choke it for a longer period of time. It's worth it. (Posted on 10/29/2018)

This is a fantastic engine kit, and is definitely a step up from the typical 66cc 2 stroke kits out there. With that said, there are a couple of things I wish I knew before I started assembling it. The first obstacle I faced is that this kit requires a 3 piece type spindle/bottom bracket with square ends to connect the included wide crank arm assembly. Since the engine is so wide (about 9.5"), a typical 5" bottom bracket spindle length isn't going to clear the motor. 6" (153mm) will clear by about 3/4" on the left side, but going wider won't hurt. If you have a cruiser type bike with a 1 piece crank, I'd recommend getting a threaded adapter and a sealed type bottom bracket (the ones with the cups and bearings are crap). The other issue is that the manual doesn't mention the screen inserted in the fuel shutoff valve (I accidently ditched mine thinking it was some kind of cap that needed to be tossed before assembly) or the orientation of the fuel filter. Some more info on carburetor tuning adjustments would have been helpful as well, but I realize there are many resources for these things elsewhere - especially the forums. Technical issues aside, the engine is pretty quiet and seems like it'll hold up nicely. Having the battery and generator is a great feature for adding lights, turn signals, and anything else requiring a 12V supply. Overall, I'm very happy with the purchase. (Posted on 10/24/2018)

standard deal regular power (Posted on 9/18/2018)

I haven't installed it yet, however this kit looks amazing!!! All of the parts are better quality even the rubber sprocket holder. I have been a motorcycle tech for 20 years and I can tell that this is going to be an easy install. It's the same as the china girls just some extra wires and components to connect. I like the quality of the engine; the metal and the paint. I will write a review on performance after break in. (Posted on 9/9/2018)

I bought one about a year ago used for months with no problems it always started right up on the first try. But then one day I was going down the road and it revved up on me and would not go into gear when I got to look at it the main drive shaft broke I don't know what caused it but other than that it ran good until then it still starts right up but won't go in the gear. I'm going to have to rebuild it or just buy a new one (Posted on 9/6/2018)

Even though it took a while to get all the kinks worked out, this engine by far is the best one that I've ever had. I worked with Bikeberry support to figure out why it wouldn't start and they shipped out all of the needed replacement parts as promised The electric start is so awesome and the motor is rock solid. I am 260 lbs and this thing still hauls me around with no issues. I highly recommend watching the video before installing the kit and be sure to mix the right oil to gas ratio or you will have problems. I also recommend getting a good cruiser type bike that can handle a lot of weight because this thing is heavy. . (Posted on 8/13/2018)

Out of the 3 engine kits that I purchased from BB,this was the easiest to put together. The Youtube video was somewhat helpful and the manual was ok. My only gripe is that the wide crank set didn't come the complete bottom bracket assembly. I also recommend a heavy duty kickstand, good tires and a good pair of brakes. (Posted on 6/4/2018)

Me and my friends have had this engine and used for a while about 5 months with daily riding. I have had nothing to say at first besides how this engine rode so smooth and the electric start is very useful. However the battery did die on me once so I had to use the pull start to start it up but it started on the 2nd try. Awesome kit could say more but not needed just look at the other reviews. Please buy if you want a good kit! (Posted on 6/1/2018)

i had one it was my ride to work i love it but someone cut my lock and took it i had the motorized mags,, green tires had the hulk on gas, tank it was pretty cool looking worked really hard making her look nice,but going ,start all over again and i will buy one of these kits again ,thanks again bb. (Posted on 3/25/2018)

They have no power and they have no speed. There junk!!!!

BIKEBERRY RESPONSE: Hi Bruce, really sorry to hear that you're having this issue. The bullet train engine is in fact one of our most reliable and powerful 2 stroke engine kits. In 95% of cases where riders have an issue with the power or speed of their bullet train engine, it is caused by the carburetor not being tuned properly. Bear in mind that due to differing altitudes and atmospheric conditions, all 2 stroke carburetors need to be tuned for the local atmospheric conditions for optimal performance. We encourage you to watch our youtube video on how to tune a carburetor. (Posted on 2/25/2018)

This thing is heavy. Due to the add on of a centrifugal clutch, a battery, the engine is big. It comes with a wide crank pedal assembly to accommodate for the engine but mine was missing the metal rod that attaches the pedals together. Bike berry sent one out no problem. Thank you. Finally got it running and noticed a small pin hole above the engine right underneath the carburetor. After I'd run it for 10 min or so i would find gear oil on to of my engine. So a few weird quarks. I haven't put many miles on it yet. I built it around Christmas time in Washington. So its been to cold. Did full synthetic everything should be good by the time I can run it longer. Oh also it keeps dying on me. I opened the gas tank with a small hole for extra air. Buying a wider hose soon. Love some ideas. (Posted on 2/8/2018)

What else can be said? The future of motorized bikes, leaps and bound better than the regular 2 strokes... It's all true. There is no comparison. I have 2 of the highest quality 2 strokes (Grubee). The Bullet Train leaves even those behind. The electric start and the auto clutch are well worth the hassle of finding a place for and mounting the battery and electric box. The engine is powerful and vibrations are surprisingly minimal. A real electric system allows operating lights, turn signals, horn, etc., and at the same time really charges the battery. Never spending a dime on other engines. (Posted on 2/8/2018)

Every one Loves the way it starts. The install was good. I had to change the way you mount the battery under the bike. had to some welling. I used a Hyper bike from walmart cost $107.00 with tax The box will fit under gas tank. Rides Great. (Posted on 2/7/2018)

Motor seems much higher quality than your average two stroke and everything but the fuel tank and battery box bolted on a genesis astra with no need for modification. (Posted on 11/3/2017)

The engine itself is great. I would recommend you also buy the "BBR Tuning Performance Spring Idler Pulley Upgrade" as wells as the rear BBR Tuning sprocket and adapter mount upgrade. I neglected to buy the later and now i have broken spokes (Posted on 10/6/2017)

I've had this engine on my Schwinn Jaguar (the jag...) for about 5 months now and I cannot say enough good about it. Fires up EVERY time, quick and easy. It is quiet, like the 4 strokes, and the automatic clutch makes for an easy ride. It's smooth, easy to maintain, great on gas. I mean, I spend ten bucks a month on gas for this thing, so yea... Definitely worth every penny, and as for other 2 stroke kits? No comparison. If you want a dependable motorized bike you'll get this kit... (Posted on 7/21/2017)

What does an 83 year old man do when he can't drive a car any longer? I know! He keeps going. I knew the answer was motorized bicycles for all his transport s tion needs. Right away, what I did was....make a lot of mistakes buying junk engine kits. They ran, but had little power and since I could barely pedal due to physical disabilities, I tried two more times which were two more mistakes. Then, something new arrived at bikeberry. This Bullet electric start was exactly what I needed. Easy to install....easy to really get down the road fast. This engine has been so good that I bought another, and got the same great result. I gave the 1st one to my also great 26 year old daughter, so now I need another one. Take an old man's advice.you'll really go with this engine. (Posted on 7/6/2017)

I've been riding, racing and building motorised bicycles for well over 20yrs, mainly China girl 2 strokes,, and I'm happy too say the new bt 80 is definitely the new generation of affordable 2 stroke Bolt in motors. Easy install if u have played with China 2 strokes b4 u won't have a prob.. Expect alot more torque.. Easy and I mean too damn easy starting,, smother ride,, 12v power supply for lights, indicators,, I've even seen a stereo installed using this kit... Replace the stock crap nuts n bolts and source a decent carby and exhaust and it's a damn beast.. I haven't even bothers too port it out and it keeps up with motors worth over double. (Posted on 5/23/2017)

The motor is great, you can tell from the build quality that this isn't just a regular motor that have been on the market for years. Everything on it is better, even the metal they use to build the block. (Posted on 5/9/2017)

I've now had this motor six months and still runs great I ride it to work 5 days a week , one problem ive experienced was a very noisy clutch with slight vibration, after opening clutch cover I discovered a loose center bolt once tightened clutch ran great. (Posted on 4/29/2017)

i got this kit fuel fiter was cracked and one wire in elec. box was wrong plug in for it just smash wire plugged it in and it starteded put this kit on beach cruiser rides smooth and its great ride love elec start but we had to mount elec box on top bar behind gas tank you shold make wires longer you can zip tie them but this a great kit i would buy same one again its cool got it put togather and went 32 mph them stopped got break it in thanks bb ride man dont wont to blow her up (Posted on 4/7/2017)

This was my first bike build and I am impressed with this motor. Like the electric start and will fire up every time. I would definitely recommend this engine and I will probably buy another one because I can't keep my wife off mine. (Posted on 4/1/2017)

it runs well and is very fast. I use to have the regular china girl Flying horse and this one is a night and day difference. It's more like a motorcycle than a motorized bike. (Posted on 1/12/2017)

Gonna lay this out real simple, this thing is nice.

Pros:
-Electric start (it was 5 degrees F today, and it started right up with no choking whatsoever)
-Carb is pretty close, as far as jetting goes (works near perfect in cold weather, your mileage may vary, will probably be on the rich side for most)
-Smooth (with a 44T sprocket on a 27" wheel, I hit 30 before I backed off, and it was due to me going easy on it, not the vibration)
-Powerful (centrifugal clutch combined with it's increased power over a stock china girl means it can get rolling from a dead stop pretty easy, not good for your wheel though, you can snap spokes by accelerating too harshly)
-Quality (the engine itself is well manufactured for the country of origin and the price point)
-Spares (mine came with an entire spare top end, a bunch of spare nuts and bolts for everything, and a spare exhaust gasket)
-Battery (way more powerful than it needs to be, combined with the engine's stator you would have no problem running lights/turn signals with plenty of extra charge to go around)

Cons:
-Kit is not as advertised in the manual or description (it comes with a 48T, as shown by what I received and the product image, very slight and unimportant differences otherwise)
-Kit itself is the usual junk (chain, chainguard, carb, chain tensioner, fuel tank, et cetera; everything but the engine and battery is the usual low quality stuff you get with these kits, it works, but you'll want to upgrade; quality chain, ditch the chainguard, an RT/Puch/Mikuni/Dellorto carb, a spring chain tensioner, and a bigger fuel tank will do you well)

A few tips for putting it together that haven't been said:
-Be prepared to shim your frame: on a standard steel frame bike, the electric box and chain tensioner may be too big to fit properly
-After connecting the battery, be careful about letting any of the positive terminals touch your engine or frame, since the ground is your engine/frame
-Unless you have to pull up huge hills or are rather heavy, I'd downsize to a 44, 41, or even 38 tooth sprocket depending on your weight, bike, and needs
-Either use blue Loctite (or equivalent nylon threadlocker) on everything, or replace all the factory nuts with appropriately sized locknuts. Better yet, do both.
-Make sure your chain is taught and straight, you do not want to throw the chain at 30+mph (Posted on 1/6/2017)

This engine bolted up to my cruiser style frame no problem. The installation took me about five hours, and when I filled it with gas in the morning, it started right up. The instructions are relatively clear to understand, and anyone who has experience building the manual pedal start engine kits wont have any problem assembling this one. I've already ran it for a good while, and have concluded that this is indeed a quality engine. choking is often unnecessary when warm starting the engine. Just a quick press of the start button and off you go. There is a post-clutch freewheel so if you're going down a hill and you come off the gas, the engine wont drag along. The clutch engages pretty much as soon as you're on the throttle, and it makes my bike go "very fast" to say the least. All in all, this engine kit is a phenomenal next step for builders ready to take on the challenge and responsibility of a larger engine. (Posted on 10/27/2016)

I find this engine to very hardy and reliable. It's definitely a great upgrade to the standard PK80. The electric start has been flawless. The performance has been outstanding. I plan on buying another for a future build. (Posted on 10/21/2016)

I have been riding on this kit for about a month and I love it the fact that it has a alternator and a starter is so cool It has been so realible that I dont even bring my toolbag on my rides I just lean back and cruise and enjoy my ride thank you bikeberry for this kit and you can bet I will be puchasing more of theses babies. (Posted on 10/14/2016)

This is a great engine kit I remember having to kick start or pedal start the old original 2stroke engine kits in cold weather trying to get ready for work the BT-80 starts up without no problems once u tune the NT-carb this engine takes off with very little pedaling its a very powerful engine I'm running the 44t BBR Sprocket adapter the engine has very little vibrations so little that I can't tell it's running the automatic clutch is sweet with pedaling the bicycle normal while the engine is off you barely notice your engine chain is spinning its so many good things about this engine u just have to try it out u won't be disappointed I believe this is the future of motorized biking (Posted on 10/1/2016)

tis engine kit is da dope dog I hook it to a bike and it did 40mph its so radical (Posted on 9/30/2016)

Upon arrival from Californa to Georgia in 5 days ") the kit was in pristine condition. I mounted the engine with a cns carb and man does it purr. Ive only put 5 hours on the engine but have found the overall performance to be outstanding. Buy it and you wont regret it. Ride on brothers and sisters, ride on. (Posted on 8/20/2016)