Engine Group

Bore-up, camshafts, carburetters..
Tuning parts for Honda, Jincheng, FYM, X-Sport, Madass, Chinese brands...

Help with engine types and specifications

Help with selecting the correct piston type
Help With selecting the correct tuning part for your bike. Contact our technical department:

IMPORTANT NOTE
If you bore-up your engine, you will need to run it on premium fuel. We recommend you also use an octane booster.
For example: Silkolene Pro Boost added at 1.5% ( we cannot send octane booster through the postal system)
If you use low grade fuel your engine could overheat and failure will occur.

Mega Kit
# MEGAKIT
JINCHENG MEGA KIT, Our best selling tune up kit all in one package!
the JMK fitting guide.

Bore Up kits


fitting guide.
Note: Bore up kits require your bike to be geared up to take full advantage of the extra power gained.
To get the most from your bore up kit you can fit a larger carburetter. See our carb kits on the INTAKE section.

49 >> 72 Best Seller!
# MBD72HC1
MBD 72cc High Compression Bore Up kit for 6v 49cc Honda or Jincheng JC50Q-7 (M50). (includes: iron cylinder, domed 47mm piston kit & top end gasket set)
This Bore Up kit uses the original 49cc Jincheng/Honda cylinder head with excellent results. 50mph with 20mm carb kit and 28T rear sprocket.
To fit 6v Honda & Jincheng Monkey £78.00. oversize pistons available.
Don't forget to gear up!

Similar kits for other models. Honda 12v GK4, Madass, Other Chinese brands etc.
Please phone or e-mail for prices.

49 >> 85
# MBD85HC1
MBD 85cc High Compression Bore Up kit for 6v 49cc Honda or Jincheng JC50Q-7 (M50). (includes: iron cylinder, domed 51mm piston kit & top end gasket set)
This Bore Up kit uses the original 49cc cylinder head with excellent results. £98.50
Don't forget to gear up!

Similar kits for other models. Honda 12v GK4, Madass, Other Chinese brands etc.
Please phone or e-mail for prices.

Cam chain & roller wheels
# MBDCC1
Cam chain, 50,70 £12.57

# MBDCC2
Cam chain, 90, 110 £12.57

# MBDCRK
Cam chain roller and sprocket wheel kit. Includes: Cam chain rubber wheel, cam chain tensioner wheel & oil pump sprocket wheel
(fits all 12v engines & Chinese). £6.50

Camshaft, "Fast road".

# MBDUC
Ultra Racing Camshaft for Chinese (WIDE CAM) 110 engines. - Inlet lift = 6.15mm Exhaust lift = 6.00mm - Now available,
makes a real GROWLER out of the Chinese engines. Bearing sizes 35mm/32mm (can be fitted without removing the cylinder head) £98.00

# MBDUC2
Ultra Racing Camshaft for Chinese 50, 72, 90, 100 and 125 engines. GOOD FOR X-SPORT & THUMP STAR. - Inlet lift = 6.15mm Exhaust lift = 6.00mm - Now available
, makes a real GROWLER out of the Chinese engines. (can be fitted without removing the cylinder head) £98.00

# MBDUC3
Ultra Racing camshaft for Honda Cub C90 head, 2 bearing type camshaft (42mm \ 28mm). £45.00 (SPECIAL OFFER)

# MBDUC4
Ultra Racing camshaft for BORED UP HONDA ENGINE OVER 85cc, 2 bearing type camshaft (42mm \ 28mm). £45.00

# MBDUC5
Ultra Racing camshaft for LIFAN and Zongshen 120cc MONSTER engines, 2 bearing type camshaft (42mm \ 28mm).
£98.00 (requires MBDCSS camshaft sprocket. See below)

# MBDCSS
Sprocket to suit Z40 camshaft for LIFAN and Zongshen 120cc MONSTER engines. 2 bolt fixing. £14.50

Clutch.
# MBDCLC-1

Hand clutch conversion kit. 2 plate, £95.00 ** now includes left hand control lever and clutch cable**

to see clutch assembly diagram.


DAYTONA, clutch inspection cover, purple £31.73

# MBDCP1
Clutch friction plates for 12v 4 plate clutch (110 engines etc) £14.00 / set.
# MBDCP2
Clutch friction plates for 12v 2 plate clutch (110 engines etc) £7.00 / set.


Uprated clutch springs.
# MBDHDCS-1
Heavy duty clutch spring set (4) for Hand clutch engines. SS50, Chinese engines, Ex-Sport, Thump Star etc,, £12.00 / set.

# MBDHDCS-2
Heavy duty clutch spring set (4) for Auto clutch engines. C50, Z50, Jincheng M50 etc,, £8.50 / set.

Chrome Clutch Casing (right hand crankcase cover)
# MBDCRHC
Chrome plated clutch casing. Fits all manual clutch on crankshaft type engines. Honda and Chinese engines.

Now in stock 4 speed gear box kits!!

Crankshaft
# MBDRC-52-6v
Racing crank, 52mm stroke, 6v type, (Jincheng JC50Q-7, ER M50, Honda 6v), £146.88

# MBDRC-52-12v
Racing crank, 52mm stroke, 12v type, (HONDA XR50, CRF50, Hongdu, Jincheng Dirt Monkey, Chinese 50, 70) £146.88

The Racing Crank will lengthen the stroke of your 50cc engine which will increase the engine capacity (see the table below) The lightened crank flywheels on the Racing Crank make the engine very "snappy" and responsive. This is a great option if you already have a hand clutch and 4 speed gearbox.
Here's what the Racing Crank will do to your engine:
72cc 47mm bore >> 90cc,
85cc 50mm bore >> 102cc,
88cc 52mm bore >> 112cc
Please phone for advise on which piston to use with this crank.

NEW
For mainland UK customers we now offer a fitting service for the Racing Crank. We can collect your engine from your home or work address, carry out the conversion for you and then return the engine to you ready to go!
All engines are run before we ship them back to you. Please call to discuss this service: 01264 710 074

Cylinders (not bore-up kits)
Note: The 49cc series cylinders are 62.6mm long and the 89cc series (GB5) cylinders are 69.17mm long. Face to face.

49cc series:
# MBD49CYL
49cc (39mm) Iron Cylinder, Honda pattern, £35.00

# MBD72CYL
72cc (47mm) Iron Cylinder, Honda pattern, £44.00

# MBD51CYL
85cc (51mm) Iron Cylinder, Honda pattern, £54.00

# MBD52CYL-A
88cc (52mm) Alloy Cylinder, Honda pattern, £75.20

89cc series (GB5):
# MBD110CYL
110 (52.4mm) Iron Cylinder, GB5 Honda pattern, £59.00 (Requires the crankcase opening machining to 57.00mm Dia.)

# MBD110CYL-A
110 (52.4mm) Alloy Cylinder, GB5, £89.00 (Requires the crankcase opening machining to 57.00mm Dia.)

# MBD110CYL-A-N
110 (52.4mm) Honda Nice pattern Alloy Cylinder, £99.00 Will bore out to 54mm

Cylinder Head (Big Valve Head) Excellent power upgrade for GK4 49cc heads.

# MBD72HEAD
72cc Cylinder head, complete with camshaft, valves and R.H. cover, £85.00
Inlet port - 24mm dia.

Inlet valve - 23mm dia.
Exhaust valve - 20mm dia.

# MBD72HEAD2
72cc Ultra Cylinder head, same as above but with racing camshaft,£169.00
Inlet port - 24mm dia.

Inlet valve - 23mm dia.
Exhaust valve - 20mm dia.
See our piston list for suitability. click here.

Cylinder Head Covers
# MBDLHHC-1
Left hand cylinder head cover with fins £12.00

# MBDLHHC-2
Left hand cylinder head cover polished alloy. £6.00

Cylinder Head Camshaft Covers
# MBDCC-1
Camshaft/rocker head cover £4.25

Valves
# MBDEXV-1
Exhaust valve, 20mm head dia., 4.96mm stem dia., 65mm O/A length £9.50

# MBDINV-1
Inlet valve, 23mm head dia., 4.96mm stem dia., 65mm O/A length £9.50

Gaskets
Gaskets - Top end
# MBDTEGS
All 50/70/90 top end gasket sets £9.50 each. state year/model.

Gaskets - Full set
# MBDFGS
All 50/70/90 full gasket sets £12.00 each. state year/model.

Gaskets - Cylinder Head
# MBD47HG
47.00mm (72cc) Cylinder head gasket, £4.25

# MBD52.4HG
52.4mm (108cc) Cylinder head gasket, £4.50

#9022B-IA24-0000
54.00mm (124cc) Cylinder head gasket, £5.25 (for Chinese 125 engines)

Gaskets - Cylinder Base
# MBD47BG
47.00mm (72cc) Cylinder base gasket, for Honda £2.00

#100033
49cc & 72cc Cylinder base gasket for Jincheng M50, Panda Fun Runner, £2.00

# MBD52.4BG
52.4mm (108cc) Cylinder base gasket, £2.00

Gaskets - Cam cover
# MBDCCG
Cam cover gasket (all models) £0.75

Gaskets - Crankcase to Crankcase,
# MBDCRCG
R.Crankcase to L.Crankcase gasket (all models) £2.15

Gaskets - Camshaft sprocket cover
# MBDCSCG
Camshaft sprocket cover gasket (all models) £0.75

Gaskets - Right hand head cover
# MBDRHCYLG
Right hand cylinder head cover gasket (20.5mm camshaft hole) £0.75

Gaskets - R/H engine
# MBDRHCG
Right hand engine case gasket, (all models) £2.15

Gaskets - Inlet
# MBDIPG
Inlet pipe to cylinder head gasket, (45mm screw hole centres) £0.75

Gaskets - Exhaust
# MBDEXG
All Exhaust gaskets, (all models 50,70,90,100,110,125) £1.95

Gearbox
# MBD4SGB-1
4 speed gearbox cluster to suit Jincheng etc. £65.00

Oil Cooler Kit
# MBDOKM
MBD Oil Cooler matrix only, bolts onto horn mounting hole, £ask

# MBDOCP
MBD Oil Cooler plate (all Honda, Jincheng & Jialing OHC) £ask

# MBDOKK
MBD Oil Cooler Kit £149.00 (all Honda, Jincheng & Jialing OHC) bolts on to the Monkey horn mounting hole. )

Oil Catch Tank Kit

Oil Pump (HV)
# MBDHPOP
High volume oil pump (requires oil hole in crankcase opening to 1.64mm) £29.95

Oil Seals
# MBDOSS1
Oil Seal Set, (Jincheng & Honda)
(kick shaft, gear shaft, sprocket shaft, large magneto 'O' ring, mag screw 'O' rings x2 ), £9.95 set.

Piston Kits (not bore-up kits)

Crown height measuring information.
rings fitting guide.
Help with selecting the correct piston type

We have pistons to fit most applications.39mm, 47mm, 50mm, 52mm, 52.4mm, 54mm
This section of our web page is currently being revised. Thank you for your patience.

Piston ring sets
# MBD39RS
39mm (49cc) Piston ring set £12.00

# MBD47RS
47mm (72cc) Piston ring set £14.00

# MBD52.4RS
52.4mm (110cc) Piston ring set £16.00

Rocker Caps

# MBDRC-2
Rocker caps, finned, chromed aluminium with "O" ring seal £9.95 each.

Back in stock!
Alloy rocker box cap with breather spout. £14.10 each.

Screw Sets (engine case - coloured)
# MBDHBA
Hyperbolt anodised alloy screw sets, auto clutch Monkey & Dax, £19.50

# MBDHBH
Hyperbolt anodised alloy screw sets, hand clutch Monkey & Dax, £19.50

Spark plug
# CR7HS
NGK CR7HS "R" plug. To suit: Monkey, Dax, Cub 50, Cub 70, Cub 90 £2.75