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GY6 Cylinder Rebuild Kits Kymlaa 100cc Big Bore Kit for 69mm Valve 49CC 50CC 139QMB Moped Scooter Engine 50mm Bore Upgrade Set with 6pin Racing CDI Ignition Coil Performance Spark Plug Clutch Spring

Based on 225 reviews
Condition: New
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$79.97
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Availability: Only 6 left in stock, order soon!
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Arrives Sunday, Nov 1
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At a glance

Condition
New
Model
KYMLAA-00050-1
Weight
6.6 lb

Features 5

  • This big cylinder kit will upgrade your gy6 50cc 60cc 80cc to 100cc, without EGR, to get more RPM,more power, faster maximum speed.
  • 69mm valve length version
  • Simple Installation
  • With cylinder body kits, cylinder head kits, camshaft, camshaft seat kits, gaskets kits, oil pump and gear, spring sets, copper roller sets, 6pins racing AC CDI, ignition coil and racing 3-electrode spark plug

Description

Size:69mm Valve Length Fitment: Jonway 49cc 50cc 4 stroke scooters like warrior 50 50cc 4 stroke like Agility 50,People S50 4T,Suer 8 50 4T Pagsta mini 49cc Baja 49cc 50cc 4stroke scooters like motorsports SC-50 sun city,primo,DR50,Dirt Runner 49 Baotian BT49QT-2,BT49QT-7,BT49QT-9,BT50QT-9,BT50QT-11 Dotera 50QT-11 Eton 49cc 50cc 4stroke like Sport 50 Fly 49cc 50cc 4-stroke scooters Jalon JL50QT-15,JL50QT-16,JL50QT-18,JL50QT-21,JL50QT-21 Falcon. Jinlun 49cc 50cc 4-stroke scooters Roketa 49cc 50cc 4 stroke scooter such Bahama,Maui,Sicily,Tank,Baotian 50QT-9 Sinski XSJ50QT-6, XSJ50QT-B SSR Lazer 5 Moped Sunl SL50QT-16, SL50QT-18,SL50QT-2,SL50QT-3 Tank 49cc 50cc 4-stroke scooters Taotao 49cc 50cc 4 stroke scooter such as GT5,Fastwind,AMT50-A1,CY50-A,CY50-B,CY50-T3,Funny50,Roman 50,Retro 50,Speedy50,Venus50 Verucci VC50TS-3M VIP future champion 4 stroke Zhong Hu 50cc,Zongshen Metro 50cc Zongshen ZS50QT-4 Many more GY6 4-stroke 49cc 50cc 60cc 80cc from china. engine Specifications: Bore: 50mm Displacement:100cc Valve Length: 69mm Pacakage Included: 1 x Set of 6 Gram Racing Pure Copper Roller Weights 1 x Cylinder Head with 69mm valve with Update Camshaft. 1 x Rocker Arms Assembly 2 x Valve Seals 1 x Oil Pump Assy with Driving Gear 1 x 50mm Bore Cylinder Block 1 x Set of 50mm Piston Assy, Piston, Rings and Wrist Pin 1 x Full Set of Engine Gasket 1 x Set of Intake Manifold and Muffler Bolts, and Exhaust locking hat 1 x 6pins Racing AC CDI 1 x Racing Ignition Coil 1 x Racing 3-electrode A7TC Spark Plug 1 x Set of Clutch Small Racing Spring 1 x Racing Clutch Big Spring

Specs 6

Manufacturer KYMLAA
Brand KYMLAA
Item Weight 6.6 pounds
Package Dimensions 10.31 x 7.24 x 6.18 inches
Item model number KYMLAA-00050-1
Manufacturer Part Number KYMLAA-00050-1

Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Sunday, Nov 1

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

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Top Amazon Reviews


Perfect fit. Perfect install. Way better power. Great product for the price.
If there is a single bad review on this item it was either a fluke or lack of installer experience. This kit came exactly as shown. Was very easy to install, and took 2 hours total and wasn't even rushing. Watch a few YouTube videos and DO NOT RUSH! Everything went together perfect, and smooth. All parts including exhaust studs were absolutely fine and same as stock. Bike started up within a few cranks once gas got back in to the carb. The power is night and day. Have no problem getting my tao 50 pony up to 40-45mph now, and quickly. Pulls wheelies fairly easily now as well. Literally was getting smoked by my buddies mopeds earlier in the day, and went back to his house after install and put bus lengths on his 2 stroke moped. Much more responsive. Keep in mind I already had an upgraded jet (85) and intake and exhaust and a 7/5gram split slider swap. But literally runs perfect as is with only a small idle adjustment. Highly suggest this kit. I haven't even installed the cdi, clutch springs, or big main engine gaskets either. Only complaint I have is the spark plugs that keep coming with these kits and the cdi kits are trash. Use ur stock plug or a new stock one. Other then that we'll worth the money and definitely a good buy. ... show more
Reviewed in the United States on September 4, 2023 by Amazon Customer

100% real deal!
It came and was packaged well and with everything pictured and advertised in the description of what is included. I have not installed it on the bike yet but an billing to get started on it today. So fingers crossed! Right now I have to give 5 stars. So lyk how it goes!! And thank you so much
Reviewed in the United States on September 3, 2026 by Cristina Raines Riffe

Bad cam shaft!!!
I would say this kit is really good. I followed a YouTube video step by step and it was super easy. But yes I am very mechanically inclined. Only bad would be the new cam shaft that was with the kit wasn't good. So I used the oem and it works great starts right up and definitely goes. Definitely worth it!!! ... show more
Reviewed in the United States on May 1, 2025 by Anthony Smock

Awesome kit
I had an issue getting the first one I ordered running they sent a whole replacement and it works perfectly! Runs amazing, pretty fast now.
Reviewed in the United States on July 10, 2026 by Rylee

as described Daughter Happy
Bought a 49CC scooter for my Daughter for Collage, But it took 2 blocks to reach 30mph, any hill it would go from 30mph to 10mph (top speed downhill 35mph) not cool. I deemed it to be too dangerous do to the speeds on the roads near the collage was 35 to 45mph in a hilly area. OK so I installed this kit and a aftermarket Exhaust. Now she out accelerates my wife's car from 0 to 20mph top speed 45mph on the flat, going up a 6% grade hill she holds 35mph So this year we took her to the 2024 Sturgis Motorcycle Rally in Sturgis, South Dakota and she rode her Scooter down Main Street with the Big Bad Harley's and Indian's. My Daughter had a blast over 200 miles on this kit. PS took about 3 hours to install this includes watching the videos on how to do it. Good luck and happy Scootering/Biking ... show more
Reviewed in the United States on August 21, 2024 by Steven Peterson

Decent kit, but has its issues
I bought this and installed it on my Chinese scooter, which wasn’t super difficult. The main gripes i have with it are that the ring gaps are out of spec. They’re bigger than they should be to run at its full potential. The second thing is the valve train. One of the things I noticed right off the bat after getting it running was that the valve train was noisy. It is much louder than it should be, and I adjusted the valve tappets at least two times to no avail. I didn’t end up using any of the cdi, coil, spark plug, or clutch parts, so I don’t know how good quality those were, but the castings were overall pretty decent. I wouldn’t really recommend this kit, I would spend some more on maybe some individual parts from a more reputable company. The customer service was good as I contacted them about the ring gaps and they gave me a partial refund. ... show more
Reviewed in the United States on June 14, 2026 by Jay Anderson

Bore kit
Perfect other than the spark plug cable didn't work
Reviewed in the United States on June 11, 2024 by Glenn

WILL DESTROY YOUR MOTOR!
It was extremely bad quality, there was multiple areas that were chipped causing leakage and the metal was so weak you could literally pick it off metal chunks. I would imagine it would be incredible easy to destroy your motor using this bore kit. These amazon kits are all made by the same company with absolute terrible quality. ... show more
Reviewed in the United States on August 29, 2025 by Jake van
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