Guide: Preparing a block for a Big bore cylinder (part 1)

Malossi Big Bore 87cc
The kit will not fit without processing the block to fit the cylinder skirt.
Many are excessively afraid to process block..
You do not need to point out that with a CNC milling machine makes the job more accurately, it is obvious
But I will prove that you can do the work "good enough" with simple tools


Check out the youtubeclip att the end



picture 01
The Malossi Big Bore cylinder


picture 02
The hole in the engine block is about 51.5 mm


picture 03
The diameter of the cylinder skirt is about 55.5 mm


picture 04
The drawing from Malossis the hole should be 56.7 mm (tolerance +0.1 mm) and depth 21mm


picture 05
I use the cylinder basegasket as a template


picture 06
Tip
It helps if you screw the gasket with studs


picture 07
Since I use a scribe to mark the edges


picture 08
A carbidecutter does the job


picture 09
Follow the edge counterclockwise
Tip
Save the "line" you scribed (do not cut it out) and measure while you work
let the cutter work dont press i hard


picture 10
Try to get the hole vertically and at least 21mm deep


picture 11
I finish of with a "sand disc"


picture 12
Then I take the two corresponding sides in the same way
(cutter first sanding disc afterwards)


picture 13
Measure the diameter of the hole


picture 14
Tolerance is 56.7 to 56.8 mm


picture 15
and 21mm deep


picture 16
I check that the cylinder goes on without jamming
Looks good so far!


picture 17
Later i will cut out the channels marked with black

Continue to follow my work to fit a Malossi 87cc Big bore kit on my Aerox

 

Looks awesome thanks for this video, may help me in future.

 

if you look he has 4 page thread on here http://www.scootershack.co.uk/threads/aerox-malossi-big-bore-87cc.27196/

 

Yes that's where i got the link from

 

great guide mate

 

As much as I would still never do it manually (good enough isn't an option for me ) I really liked how you added detailed info on how to do it!

Can't wait to see your beast!