50cc upgrade kit for Blata Rep

[ALDOS]

Anyone installed a 50cc kit for a blata rep yet? Are they any good? Any info is appreciated.

[Maylands Performance]

We have a couple of Big Bore 50cc kits for B1 bikes and are in the process of fitting 1 to a customers bike .The quality of the kits is very good aand contains everything required to fit ie.[Big bore cyl,50cc piston,Piston ring,Cylinder head ass.,gudgeon pin,circlips,Gaskets,O'rings]Hopefully the customers bike will race on Saturday so we can give some decent feedback on the kits performance on the track.

[akim21]

hhmm i would be very interested in it how much are these kits?

[ALDOS]

Thanks Maylands, Keep us informed on how the bike performs. Sounds like a great cheap upgrade, and I guess you don't have to split the cases to do it!

[punkrock86]

i'll be installing one of these kits shortly too paired with 19mm dell and a rebuild with decent bearings, seals etc hoping for 12 hp

[Dazza]

With the new 50cc Blata Replica top end kits, I have been told that a new crank should be used with every instalation.
Oz Minimoto should have the full kits within 2 - 3 weeks.
We will be fitting one of these kits asap when they arrive, the out come of this kit will be documented and posted on this site.
Pricing of the top end kit has been priced at $179.00 on another forum and with another dealer at $195.00.
I haven't worked out the total price I will sell these with crankshaft yet?
This will follow when they arrive to me.

The diameter of the bore will increase from 37mm (39cc) to 39.5mm (50cc).
Stroke I am unsure of at this stage.

With ruling of what class will these race in?
This is how you may read the rules under the different clubs.

PBAA Ruling:

Class 3. STANDARD CHINESE WATERCOOLED (Junior and Senior)

3.1 Capacity: Maximum 50 cc
3.2 Crankcase: Standard Chinese origin
3.3 Crankshaft: Standard Chinese origin
3.4 Seals, Bearings, Gaskets: Open
3.5 Head/Barrel: Standard Chinese
3.6 Coil: Standard only
3.7 Timing key: Open
3.8 Flywheel: Standard without modification
3.9 Spark Plug: Open
3.10 Clutch: Standard as originally supplied
3.11 Carburettor: Open
3.12 Air filter: Open
3.13 Reed block: Standard
3.14 Reeds: Standard
3.15 Exhaust system: Open.
3.16 Tyres: Smooth or grooved Chinese manufactured tyres only.
3.17 Gear ratios: Open.
3.18 Machining: No porting, Machining (including polishing) of Barrel/head,
Crankcase, Crankshaft, Conrod, Piston or flywheel is permitted.

So I would read this as:
Yes, they can race in the stanadard class.
Because they are a standard Chinese barrel on some new Blata Reps avaliable.

MMMCI rules:
CLASS 4: CHINESE BASIC WATERCOOLED SENIORS AND JUNIORS.

• Capacity: Maximum 52 cc
• Crankcase: Chinese.
• Crankshaft: Chinese.
• Seals, Bearings, Gaskets: Open
• Barrel / Head: Standard Chinese for that model.
• Coil: Standard Chinese.
• Timing key: Standard Chinese.
• Flywheel: Original Chinese
• Spark Plug: Open
• Clutch: Standard Chinese, material open.
• Carburettor: Standard Chinese for that model.
• Air filter: Open
• Reed block: Standard Chinese.
• Reeds: Material open
• Exhaust system: Standard Chinese for that model.
• Tyres: Smooth or grooved Chinese manufactured tyres only.
• Gear ratios: Open
• Machining: No porting, Machining (including polishing) of Barrel/head, Crankcase, Crankshaft, Conrod, Piston or flywheel is permitted.

So again I read this again as:
Yes, they can race in the stanadard class.
Because they are a standard Chinese barrel on some new Blata Reps avaliable.

I don't know if this clarifies anything or just stirs it up!

[Maylands Performance]

Hi Dazza.We have fitted a Big Bore kit to a customers bike and found it nescessary to grind /relieve the crankcase on the Exhaust side to allow for piston clearance at BDC.The crankshaft would not rotate 360' without this grinding/porting .I am not sure if this applies to all B1 crankcases out there as the Chinese love making small changes to all their castings as we well know.!!!.It is possible this nesc. clearancing work may contravene the rules under which you race in Vic !!!??

[Maylands Performance]

The customers bike we fitted the B1 big bore kit to raced in W/C Elite here in SA today,and the owner was more than happy with the extra power the kit produced even grabbing himself a Win in one race,beating Polini50cc powered bikes and a Z1.Unfortunately the bike ate its reed valves [fitted by the cust] in the next race and it was all over for the day for our customer.Hopefully we will carry out some porting on the Big Bore Cyl in the next week or so & see what H/P we can get out of it !!!

[Dazza]

Thanks Maylands Performance,
Great report!
Sound like these kits fitted right will be a winner.

As with the machining work, yes this will put it up in the
Open Chinese Class 5 with the MMMCI racing.
This machining work maybe not needed with the new crank being used?

Please keep us informed.

[Maylands Performance]

Hi Dazza.The B1 Big Bore Kit piston to crankcase clearance situation would not unfortunately be remidied by crankshaft replacement,if a longer stroke crank was fitted the interference problem would actually be magnified.However the fitting of a new crank would be a good move if your existing 40cc engine has done a fair amount of hard work,or if you like replace it just to be on the safe side.[A new crank is cheap anyway !!!]
Regards Brian