Fuel screws matter!

So, I've got this hawk, it was getting crappy gas milage, and spitting smoke under acceleration and engine reving. Bad milage like 40 mpg, on a totally stock engine. I'd expect close to 60 mpg under the kind of riding the bike was getting.

The PO told me that it had been "tuned" by a mechanic recently, which made me wonder what he'd "fixed", given that when I got the bike it had scarry old tires and head bearings so tight it didn't steer right at all.

Anyway, I expected to find that he'd shimmed the needles, put in larger idle or main jets, or screwed with the float height, or that the air filter was super clogged.

Nope, nope, nope....

The only thing that wasn't completely stock in this engine was the idle screws. They were way out. so much so that when I turned them back in to 2.0 turns out from seated I had to turn the idle down from 1,700.

The before picture is how the rear left plug looked when I pulled it before doing any work.

The after pic is the same plug less than 40 miles later. I didn't clean the plugs, I just put them back in and rode it.

so, the lesson is, make sure the idle screws are set right.

before
Thu Aug 1 15:44:35 2002
original - 261 kB

after
Thu Aug 1 15:44:21 2002
original - 408 kB
Index created: Thu Aug 1 15:44:58 2002.