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,

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

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!

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.

Glad someone of your caliber is showing more chinese scooters.

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 😎😎😎🤙

Thanks just got 80 cylinder installed no issues

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

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

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.

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

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.

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

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..

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?

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

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

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

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.

We need a video on a better headlight for scooters

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.

those 3 tiny pistons are cute

Do you leave the EGR port open?

Does this use 64mm or 69mm valves

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

Some qmb139 will require case boring... some 80cc -100cc big bore kits have the thicker cylinder walls that wont fit into the 50cc cases

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

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

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

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

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

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.

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

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

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!

What did you use to scrape the old gasket off?

The thing around your clutch I see them changhing four plugesand they put four bots in it and puu

I need tools like digital torque wrench, impact tool, all sorts of socket box spanners, Latchets, Tee spanners, just mention afew. Thanks.

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

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.

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?

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

What tools do I need to change the crank shaft

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

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?

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

Awesome video

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.

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

Thank you

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

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!

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

Whats the actual size of the piston

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

What size carb do you recommend with a BBK

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

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?

It turns on but the wheel dosnt spin anymore the engine only revs

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

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.

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

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!!

My engine isn’t positioned up that high the cylinder is down more so when I do this big bore kit I’m hoping I don’t have to remove the engine off the bike

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

What’s that special tool called?

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

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!!

Exhaust was 05 right? You didn’t say anything

Is that fit peugeot kisbee 50cc 139 qmb-e

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

The beggining of the outro song sounded like ph

How many mm is the piston on this kit

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

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

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

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

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

How many miles can you do with this 90cc bigbore kit ? No chance to crack the engine base or the crank itself ?

both of the exhaust valves were at .004? I thought top one was .003 and bottom was .004. does that matter? should I change mine?

Awesome

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

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

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

I've had a few people tell me that the arrow goes up so I put it in the wrong?

Followed your tutorial but I am hearing a quiet scrape or noise when turning crank by hand exhaust and intake are off spark plug is in. Is this normal? It turns over and only has resistance where it needs to

Is it ok to use the stock cam

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

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

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

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

Does intake on piston go on top

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

I just put a 100cc big bore kit on my 50cc scooter and I hooked everything up right but my scooter isnt wanting to crank like it's trying but it cant

Is this kit available for a 2022 vitacci Denali 50?

So the exhaust valve is a 4 too?

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

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.