Valve cover has vaccum line hook up that is not on new head is this vaccum need?

[Kimcofan]

There is a vaccum line on valve cover that the new head does not have the hookup on my new kit, Is this needed or can i just cap this off? It looks like an emmision control vaccum I dont think i need this but not sure, anyone know what im talking about.  I also used the old valve lifters and cam on my new head do the valve lifters need to be adjusted more or less, they line up on the head fine just need to know what kind of adjustments need to be made if any?  Also what kind of adjustments do i have to make to the carb after everything is back together.  One more thing there is a white plastic gear in the moter what is this gears function?

[zombie]

It's not actually a vacuum line but a breather for crank case venting. You will have to make sure you have the new head vented. If not pressure builds up inside the engine causing oil to pass thru rings, valves,seals, and all sorts of other places. It is a simple job to drill, and tap for a "barb" fitting to re connect your hose.

[Kimcofan]

I do not have a drill press to drill and tap is there another solution? Also what about the other questions? Also can i just drill a hole in the top of the valve cover and stuff it with exaust mesh?

[Shaka]

Contact the place you got the kit from.  They should be able to provide definitive answers.  That way if something doesn't work, it's on them!  Zombie is right, there is typically a breather on the head to allow pressure be released.  I would assume that you will need to adjust the valve clearance if you took them apart.  As for the carb, you will typically need to go with a bigger main jet.  Only plug chops will tell for sure!  I'm not certain what the white plastic gear is.  Some engines use a plastic gear to run the oil pump.

[Kimcofan]

What is the valve clearance supposed to be set at with the 72cc kit?

[Shaka]

Not sure, that would be a good question for the place you got the kit.  I know Wordslinger has been setting his stock cylinder to .04mm intake and .03mm exhaust with excellent results if I'm not mistaken.

[Kimcofan]

yeah but he does not have the big bore kit he also has a 2 stroke while i have a 4 stroke

[Shaka]

Wordslingers is a 4 stroke, 2 strokes don't use valves, much simpler!   He does not have the big bore though, that is why it may be different clearance.  I would really consult the people you got the kit from.  Otherwise, you might try posting on scooterinvasion.net.  The guys there are into some serious performance tuning and may be able to give you a quick answer.

[Kimcofan]

I called the supplier and they told me they get that question frequantly that its fine to seal that vent off, it wont be a problem

[Shaka]

Nice to hear your supplier was helpful!

[zombie]

WRONG!!! You HAVE to vent the crankcase!!! Maybe there is a vent built into the head? There MUST be a vent somewhere!

[Kimcofan]

I dont know I asked the supplier if i would blow out the gaskets and he said I wouldnt maybe there is one built into the head I was just going to use the old head it looked like it was almost exactly the same.  My buddy said that vent actually goes to the petcock which has a diaphram in it that regulates fuel so i guess im going to have to research more

[Shaka]

The vacuum that operates your petcock either attaches to the carb or the intake manifold.  The one that attaches to the head is just a breather to allow for the expansion of the oil and moving parts inside.

[wordslinger]

...valve cover vent needs to be in place...your buddy was maybe confusing it with another hose...if you remember, the other end ofthe hose on your original was open to atmosphere...