This modification requires the slight trimming of the rear Carena fender
If installing the 17.5mm carburetor conversion kit,
first install rubber inlet manifold, and attach 17.5mm carburetor.

If installing airbox conversion onto 14mm carb, first install plastic
adapter flange onto aluminum carb intake flange.

Attach airbox at an angle

…to clear the expansion chamber

Grind a small relief in the rear fender to accommodate the airbox

Finished installation

Source : http://www.midsouthminimoto.com

We receive many tech calls and E-mails about spark plugs, and there seems to be quite a bit of confusion about the difference between long and short plugs, and which plug should go into which engine.  Polini has changed over to using only long plugs now in their engines, but many older bikes still remain in the field, and many have had their plugs replaced with ones incorrect for the application.  New owners of used bikes may not know what plug originally came in their motor when it comes time for replacement.

The tech tip below explains with pictures the differences between a short spark plug tower head and a long spark plug tower head (water-cooled engine examples used for illustration).

The Long and the Short of it…

On the left is a short-tower head (standard mount-style), and its correct standard plug, the L82C

On the right is a long-tower head (rubber mount-style), and its correct standard plug, the N2C

As you can see by the picture, the short plug head (left) has approximately 8 internal threads on it (measuring just over 11 mm), and the long plug head has approximately 12 internal threads (over 17.5 mm).

Good boy, Sparky!

When used with their respective proper sparkplugs, the protrusion depth of the electrode into each combustion chamber is correct.  The electrode is unshrouded and free to easily ignite the mixture, and yet does not protrude too far, endangering the piston.

Bad boy, Sparky!  NO!!!

When the long plug is inserted into the short-tower head (left), the plug protrudes so far into the cylinder that it will easily collide with the piston, doing considerable damage.

When the short plug is inserted into the long-tower head, the electrode is shrouded, and would not be able to easily light off the fuel mixture, resulting in poor flame propagation, and significantly reduced power output.

Source: http://www.midsouthminimoto.com

This is a quick over view / guide to the stock carb for CAG’s.

The two pictures below are – in order – the reed side of the

carby & the airfilter side. You can see the choke plate on the

air filter side.

Pocket Bike Carb

Pocket Bike Carb

Pocket Bike Carb

As you can see above – you can end up with all sorts of dirt and stuff stuck behind that

choke plate – so when you clean up the carb – make sure you clean all that area as well.

picture 2 has the choke closed [up position]for cold starting. picture 3 has the choke

open [down position] when your engine is warm and ready.

This picture below shows the bottom of the carb, this is where the bowl is located.

The two screws on each side hold the bowl to the base of the carby while the middle

screw is a drain screw. So BEFORE you take your carb off – make sure you under this

screw and drain any fuel you have in there. This is also useful to check to make sure

your getting a good fuel flow.

Pocket Bike Carb

Pocket Bike Carb

Below is what you find when you open up the bowl – the most common problem is

that dirt & grit get stuck in this area.

Note the golden forks/prongs – the way the carby works is it fills up the bowl with fuel

- the white thing you see in there is the float – it in basic “floats” up when the bowl is

full of fuel and closes the prongs. However – if something is stuck in between the prongs

valve or something hinders this from happening – you get fuel flowing out the over flow

as the bowl fills up but does not shut off the prongs. It can be as small as a bit of grit. to

remove and clean out this, you must remove the steel pin from the gold prong and out

comes the valve [needle] make sure you blast out the tiny hole with wd-40 where this

needle valve sits The gold bit in the centre is the jet.

Pocket Bike Carb

Pocket Bike Carb

As you can see below I was trying to get a shot of the valve/piston the prongs move

when the float moves up on it. This entire area must be clean – spotless to the point

where you wonder if its the metal or your eyes playing tricks on ya for bits of grit.

the gold screw on the side is the idle screw.

Pocket Bike Carb

Also note the seal I have there stays on the carb – make sure you always check it for

cracks and stuff – if you don’t get the seal right it will leak. Of course unscrewing the

jets and blowing everything out can’t hurt if you have already pulled the carb off and

undone the bowl.

Its really as easy as that. There are other carbys, one of which I will have tomorrow

and I”ll add the pics for those and guide as they are a tad harder. These carbys as you

can see are very easy to pull apart and pul back together again. Remeber to always use

clean rags with carbs. I also like to keep an old paint brush and use fuel to give it a

good going over as well.