This was the most beautiful front end rebuild imaginable. When you started it up at the end that was the finishing touch that made it seem so simple. Of course this is not simple but you did a fabulous job of making it about as simple as it could get. I do not know of a video on any other type of motor, chainsaw, small engine or otherwise where the entire operation of rebuild was done in one video to completion. All the cuiting and editing was just great. Thanks for a great video,

Glad someone of your caliber is showing more chinese scooters.

Thanks. Found it very usefull and it helped me to do my scooter faster and properly in 2 hours. Many thanks for this video.

This video was so helpful and if I had the tools I would do my own scooter with the 80cc Big Bore Kit... Thank you so much..

After watching this tutorial I feel a lot more confident that I could do this myself. But my clumsy behind would probably end up breaking something anyway lol!

Great vid. Very informative. Keep up the great work.

Thanks just got 80 cylinder installed no issues

Thank you for illustration a good how to video. I installed my big bore kit one shot no hiccups. Thank you. Please explain about installing a tachometer and correct reading for a big bore kit. Thanks again.

I did that with my gy6 . Went from 50cc to a 80cc . Huge difference. Cvt tuning, jetting , exhaust made a huge difference. Can reach speeds up to 50. Which is nice for my backroads that require 40mph

Great tutorial video matt ...🙂👍I'm currently working on my 50cc thinking about upgrading her to a 80cc

You omitted changing the main jet or lifting the needle inside the throttle slide to allow more fuel through, also you should have oiled the cam and housing, other than that v.good tutorial.

Do you guys do installations of big bore kits? I live in Denver and have a scooter, I'd like to install a kit in, but I don't trust myself enough to take it apart and install myself. Thanks!

I'm ordering this kit with the new cam my kymco 50 agility I'm excited to do this I never done one before so learning on the fly lol

You should have a follow through on the engine break in after bbk.

A secret I figured out pull the chain mark the very center of chain with sharpie then mark cam with sharpie perfect timing every time

Does the weight or mass of the new piston remain the same as the one from lower CC? I wonder about that since I would believe any changes in that would require a new Counterweight as well. Or, how does that work? maybe a new video addresing that for those who are curious about it?

Awesome video

Im using this video to help repair my 150 i ran it without an air filter and a small rock entered the air intake and destroyed the top end... I have done a BBK kit on a 50 before and im confident i can fix my 150. Now i know to ALWAYS use an air filter 😎😎😎🤙

Talk about taxing on the price, HOLY SHIT!! $300 for 120cc jesus christ this is why i LOVE EBAY

Nice and good work Super job 50 cc beter economische now en relaxing

You have the special tool for valve adjustment. Feeler gauge is not needed. There is the scale, 1 turn divided by 12. The pitch of the screw is 0,5 mm. You turn the screw first to 0 clearance and then open as mush needed. 1/12 x 0,5 mm = 0,042 mm, 2/12 x 0,5 mm=0,083mm and 2,5/12x0,5mm=0,1mm. If you watch KZfaq Nicks Garage, he never use feeler gauge when adjusting valves in V8 motors. He opens the adjusting screw from 0 clearance half turn. Very easy method.

The 2 nuts to remove the head stud is the smartest thing I’ve seen this week.

Very good men....exelent.....

I run 150cc carbs on 50mm snm bigbore kits and i also ran into a problem trying to install one on a long case eton 4 stroke engine ill get the case number tmrw but ik its not qmb but it is a gy6 50cc engine but im now in the process of boring the case ill let you know what happens after i install the bigbore kit nd would the belt being squished nd used cause an engine to not pass 35 mph?

those 3 tiny pistons are cute

Can you recomend the parts needed to upgrade the stator and other electrical components on a kymco agility 50 scooter?

nice video! did a 90 cc measly kit on my gy6 retro grande ;-) but what mm carb do you recommend? it is a 18.5mm right now

Do you leave the EGR port open?

Thanks for video. I want to follow you to help install the monster 90cc big bore kit and camshaft in my 2021 linhai joc 49cc scooter. Will this kit work in this scooter? Thank you!

Hi, you Comment that this fits the Agility from Kymco. Just for info: I have an 125 Agility from 2018 12 inch wheels and air cooled. Do tope end of the KN25SR engine on this scooter is compatible with GY6 or similar qmb139 Chinese generic engines? Do a Cilinder kit can be fitted? Thanks in advance

Does this use 64mm or 69mm valves

can I use the stock rocker arms assembly on 100cc big bore kit or do I have to get a new one ?

My valve cover cracked after tightening it over the engine studs, The right side of the bike studs stick out more from the rock arm assembly.

Great video, it was really helpful when doing mine big bore upgrade. However when I finished and tried to start the bike it didn't. I did manually turn the engine to ensure everything was ok. I don't know what I've done wrong.

When will you have this kit available again, It’s saying sold out. I would like the 90cc big bore kit & the crankshaft to for this unit the whole set-up. Also is this the 64mm or 69mm valves? I’d like 69mm please! Thanks P.s. I’m need a bigger carb to soon!!

Can I do this to my kymco people 50 2T or is there a specific kit for me??

Can I put a 50mm head on a stock cylinder? Or do I have to get a new cylinder too? My bike is a Tao Tao atm 50

its hard trying to line up that timing. I ran out of daylight

Hi there ! It's possible to cut the case of my gy6 150cc short case ? For a bobber proyect with 16 inch wheels ??...Have a great day amigo!!

do i need to change my crankshaft and rod to put a big bore on my gilera runner 50cc?

What size carb do you recommend with a BBK

What tools do I need to change the crank shaft

with the big bore kit fron 50 to 100cc no need refit the carburator??

Great video man but I noticed that the piston is upside down. The arrow in the piston always shows the intake side. That's why it has larger gap for the valve move towards the piston.

I’m curious I’ve seen a few other videos and they said chrome piston ring up top but here you have black up top top does it differ from kits or is someone wrong

Thank you

hi, peugeot kisbee 2018 50cc enjection 139qmbj engine code. Is it compatible?

Are there still advantages with this on stock 50cc my son races 4 wheelers and can not bore thank you

Awesome video, question did you keep the factory carb and intake?

Do these pistons not use needle bearings? Is that cus its a 4 stroke if so?

Is that fit peugeot kisbee 50cc 139 qmb-e

What size carbs and jets are you guys going with with these 100 cc swaps?

Does this fit on a peugeot kisbee 50cc 139gmb-e 4T carb?

I have install the big bore kit on my 139QMB scooter. It runs great, but when my kid and I get on the scooter the pushes the rear main seal out and all of the oil leaks out. We are both total of 320 pounds. Does the back pressure increases because its too much weight for the motor to handle or do you think it’s some other issue when the big bore kit?

Two questions. First I had to bore out my base to except the 83cc piston sleeve on my qmb -139. I noticed you said this was a qmb engine, did you have to do that with that kit? Second did you ever have to install a secondary pressure relief system? Now mine is upgraded with the exhaust carb and intake not stock. I ask because I had a oil seal blow out and the answer I found was this will happen with big bore kits on long runs and the stock system won’t handle the extra crank case pressure it makes.

Where should i buy an bbk for my 50cc scooter? Its 2022 baodiao 50s3? Thanks

So I have a Kymco Like 2 50i with injector and it is painfully slow it barely gets to 27 mph. I was thinking of installing big bore kit, however I am not sure if it would make any difference, due to the injector not supplying enough fuel? Also does the rpms of the engine need to be increased in order for that to work? Currently my max rpms are at 7000. I changed variator weights, opened the rear wheel gearing and it all seems as if its not restricted. However when I drive it the top speed is all the same. I had a bump in top speed to 33 mph when I installed new belt however that was just for 1 ride and then it fell back as previous. I am desperate in making it at least go 35. I am thinking the variator plate could be undersized as when I measured it, the diameter was about 70-80mm I don't exactly remember. I saw a video of a chinese ecu pushing the engine to 10k rpm, however it is incredibly overpriced. The gear ratio of the rear wheel is secondary 12/55 and primary 12/50 with 12 inch tires and the engine is I believe longcase. I am thinking of ordering malossi 2000 variator, because variator must be the only thing restricting that scooter. I would appreciate some input. I also considered reflashing the ECU to bump the rpms because there is no cdi box, however that would be very expensive and needs to be done by motorcycle ecu mapper

What size piston and valves are with this kit? I cant find the details anywhere...

I have a 2018 SYM symply 50 I don't think this kit of compatible but does anyone know what kits / upgrades I can do to my bike o can't find any myself

Will you please do a 50cc to 150cc swap on a Dong Fang 50cc SXR I have a pic if you can't find one by name I cant find anything on them and I wanna do a swap sooo bad

Just what is that valve adjustment tool called? Not seen one before.

I have a Kymco Agility 50, do you need to bore the case for the cylinder jug to fit properly when you go this big?

What was the top speed? Looking to buy

What is the success/fail rate of the stock QMB139 crankshafts with the 90 vs the 80cc BBK's? I think I'll go 80cc since I want the engine to last, I may go all the way and install a Naraku heavy duty crankshaft and upgrade oil pump.

Is this kit available for a 2022 vitacci Denali 50?

I have a DF50SST and mine says qma139. Is it compatible? And what size carburetor would you recommend.? Even a jets size recommendation would be helpful. Thanks in advance

will this fit on a honda squash engine?

How does this big bore kit compare to the 100cc kit from J&J Power Sports?

how fast can you go with this kit?

Does my Kymco super 8 4t 50cc (2018) have the same engine as the agility ?

Will this jeopardize the reliability of my Kymco? I’ve had mine for 2 years now & it starts every time. It’s never given me any issues.

We need a video on a better headlight for scooters

What’s that special tool called?

Awesome

What is the hose he removes at exactly 6:52?

I've done this kit on a kymco agility 50 when it had about 3000KM it worked great now I have 11000KM on it and I can barley get it started it's almost like it has to much compression cause when the piston makes a revelution it sticks if anyone has any pointers let me know

What about the egr valve.... how to delete

Thanks! Set the ring gaps for a Naraku 90cc big bore for my Maddog 50cc... It would have seized if I wouldn't have checked the gaps! Were at .004 needed .008" Just used a drill press vise to hold the ring square and my wife's nail file! Shh

Is it ok to use the stock cam

A 21mm PWK carb works good on this setup nice video I put a wood block under the back wheel can make it easy to get the head off and make sure the arrow is pointing down on the piston.

After every thing done and finish what kind of horsepower is it putting out

Just bought and was installing the kit and realized I have lost the Circlips, anyone know the size and dimensions of these Circlips?

Does intake on piston go on top

Will putting a 100cc big bore kit on a 50cc , cause any long term damage to the crankshaft? And should I put on a higher volume oil pump as well?

Wait.. Did I hear you say the black ring goes on the top of the piston? Unless it's marked, I've always seen the silver ring on top and the black as the ring under it.

can you swap a larger engine into one of these scooter frames will they fit?

I have that same scooter but it is 150cc year 2021, it is compatible with all the gy6 parts? I want to put the new clutch and the 180cc kit..! Plz respond

I have a question I ordered a big bore kit 80cc for my 49cc would I have to change my carburetor or is the stock one fine? Thanks

Nice but I installed a 150cc short case in my kymco agility only issues I have is stock rear rim don't fit replaced it with a 150cc rim with stock tire now tire rubs on inside left side of case and shock any info on fixing that .thank u

Can you adapt a stator for gy6 150 into a 50cc to power fuel injection

do i need to drain the oil from it before working on it ? (asking because i do not have the tool for the bolt to drain it)

I want to upgrade my engine can you send me the link so I can purchase

With all these mods, isn't the exhaust now restrictive? Did you rejet carb?

00.4 intake and 00.4 for exhaust ???

Home does it effect gas mileage. .?

thought you only did HONDA RUCKIS swaps...sweet...

Hey I got a question I got just the 100c piston, but I didn’t get a new head can I still use the stock one ??

What happens if you get the two rings switched the one video the black was in the middle and this one is black on top do i need to tear apart

How many mm is the piston on this kit

I have a 2022 bd50qt-2a let me tell u it does 50mph stock on my gps I got it to 57mph .... I want to do a big bore but stock the reliability is perfect ..... I know a BBK can push my speed and acceleration to better heights but I don't wanna loose the reliability factor only 10w40 valvoline full synthetic since day 1 ........I actually used the oil that came in scooter for a few hundred miles then went full synthetic