Would using these forstner bits work without damaging the screw?

http://www.harborfreight.com/7-piece-3-8-eighth-inch-shank-1-4-quarter-inch-t...

I would prefer to do it without buying anything if that's possible.  I'm on a tight budget, so if there's a different way to do this, i would love to hear it!  Thanks!

sexombob wrote on 12/10/10 at 00:27:15:

These bits are made for use in a drill press or milling machine only. And depending on the quality, they are probably made for wood only.

Bummer, but what routy said can be true. I was helping my brother with his savage over thanksgiving. we pulled the brass plug and discovered that his screw was ALL the way in. No adjustment clockwise at all! whenever we turned it ccw it would start backfiring like crazy...even 1/4 turn out. performance was slightly better but the backfire was terrible when you shut the thottle down. A friend of his said he thought someone was shooting squirrls in the park...

Anyway, everyon's different. he lives at 700 ft elevation in humid Missouri. you may not need to adjust that screw at all depending on what it's doing

Thanks guys, i'll try the drill again.  

The reason i am doing this is to get rid of the backfiring and get better idling.

Bubba wrote on 12/10/10 at 07:40:24:


I don't think the engine should run at all with the idle mixture screw turned all the way in.  The typical setting is 2 1/2 turns to 3 turns.  My bike backfired a bit at 2 1/2, but this stopped when I went to 3.

I have a 2001 LS650, 7000 miles, OEM air cleaner and muffler.  Fortunately the brass plug had already been removed by a previous owner.  And they did a good job too.  Nice and clean.

I've heard that Suzuki put loctite on the idle mixture screw after adjusting it at the factory, then they put the brass cover plug over it.  Maybe your bro's idle mixture screw just needs some exercise to get it moving freely?    Be careful:  Don't overtighten it and don't mess up the slot in the brass screw.  Turn it counterclockwise first.  Then turn it clockwise until you feel resistance.  Turn it back and forth several time.  Maybe this will loosen it up.
 
The idle mixture screw in my bike turns very freely.  Perhaps too freely?  I am more than a little bit concerned that vibration will make it rotate all by itself, maybe even loosen up and fall out?

If the idle mixture screw really is all the way against the stop, could it be that the petcock on you bro's bike is leaking through the vacuum hose, resulting in a very rich mixture?

According to other posts here, there shouldn't be any traces of fuel in the vacuum hose at all.  This is the smaller of the two rubber hoses that go from the petcock to the carb:

Small hose:  Vacuum source to turn on the fuel while engine is running

Big hose:  Fuel supply to carb.

Have you checked the spark plug color?  If it's totally black then you have too much fuel (over rich mixture).

I'm not sure about the backfiring, perhaps either too lean or too rich can cause it?

As for my bike, with the mixture screw at 3 I rarely get a backfire, and when it does happen, it's always on de-acceleration in 2nd or 3rd with the throttle shut.  Also, my bike often gives one little "putt" in the muffler after I shut off the ignition.  This happens AFTER the motor stops rotating.  Question for the board?  How common is this?

Just an update on my particular issue.

I'm waiting to borrow a better drill.  My old Skil drill starts to smoke when i go slow pushing the drill against the brass plug.

It's possible your friend has a defective idle jet.

I'd swap it out and see if it improves.

Second possibility, if the idle speed was set to high to begin with, it might never get to the idle circuit.