Air leak in carb?

cyclepro101 · #1 05-20-2009, 02:32 AM

I have got a Z80 and it runs fine. I have done most of the mods including opening up the muffler, putting a larger jet in the carb, using a NGK leak and cap and going to the hotter NGK plug. I am waiting for the 36 tooth sprocket to arrive but I have a question in relation to the carb.
I have read that a stray leak in the carb can cause the engine to run lean and blow up. So ....why then do people drill extra holes in the black plastic air filter cover? I have drilled one extra one in, right in the centre and it appears to make the motor go much better down low. So how is doing this different from having a leak somewhere else? like a missing idle screw or similar.

Steve

**2door** · #2 05-20-2009, 02:11 PM

Drilling extra holes in the air cleaner cover is not the same as having air enter through an opening in the intake manifold or other areas. Too much air being drawn into the engine downsteam of the carb makes for a lean condition, (too much air to fuel mix) and can eventually damage an engine. Opening up the air cleaner cover will, supposedly, allow more air, or at least reduce the restriction imposed by the cover. To be honest I tried holes in the cover and could tell no difference in engine performance whatsoever. The engine can only take in so much air, as dictated by carb throat size, crankcase design and vacuum and cylinder effeciency, so extra holes will not give you added performance.
Port matching, ei, exhaust flange to cylinder and intake manifold flange to cylinder is one way to gain a little power but don't expect wheel standing performance gains. Hope this helps a little.
Tom

cyclepro101 · #3 05-20-2009, 09:43 PM

Thanks Tom.

Cabinfever1977 · #4 05-22-2009, 05:57 PM

actually it will go faster without the aircleaner.

**Norman** · #5 05-23-2009, 01:49 PM

It will also eat more dirt and wear out quicker with no air filter for everyday use I recommend an air
cleaner.
You guys can run with or with out an air cleaner just letting you know. the stock breather isn't much it will keep the big chunks out. Have fun. Wear them out the Chinese need the cash. I wonder if in China, do they use these engines much? I did see one mounted on a garden tiller on one of the posts I thought that was slick.
Norman