CRF 70 Air Screw Help

My 2006 crf 70 is running SUPER lean and when I went down to the carburetor to turn the air mixture screw, this is what I saw. ImageUploadedByThumper Talk1425511148.626842.jpg

There's no way to turn the screw!!!

If anyone has any suggestions I would greatly appreciate it.

My 2006 crf 70 is running SUPER lean and when I went down to the carburetor to turn the air mixture screw, this is what I saw. attachicon.gifImageUploadedByThumper Talk1425511148.626842.jpg

There's no way to turn the screw!!!

If anyone has any suggestions I would greatly appreciate it.

I recently discovered the same issue on my son's 2009 CRF70.  I took a dremel tool with a small cutting wheel and cut a slot right into the head of the brass screw.  I cut thru the carb housing material around the screw in the process but no harm done there.  Alternatively you may be able to use a small screwdriver to back out and remove the screw, then file a notch or cut one with a hack saw for a flat screwdriver blade to fit.  I read of someone else who made a "D" shaped tool to turn it.  Honda may make a tool and maybe your local shop has one.

Pull out the throttle slide and if you are lucky the needle can be raised by lowering the c-clip a notch or two.  My 2009 had a fixed needle but I bought an adjustable that fit an older machine.  Not sure when they changed to fixed.

I put a power tip on the exhaust and a pod filter so I had to install larger jets or it would run too lean.

Take note, that IS an air screw, not a fuel screw.

 

Always a good idea to check valve clearance as well.

Edited by HondaRacer37

I recently discovered the same issue on my son's 2009 CRF70. I took a dremel tool with a small cutting wheel and cut a slot right into the head of the brass screw. I cut thru the carb housing material around the screw in the process but no harm done there. Alternatively you may be able to use a small screwdriver to back out and remove the screw, then file a notch or cut one with a hack saw for a flat screwdriver blade to fit. I read of someone else who made a "D" shaped tool to turn it. Honda may make a tool and maybe your local shop has one.

Pull out the throttle slide and if you are lucky the needle can be raised by lowering the c-clip a notch or two. My 2009 had a fixed needle but I bought an adjustable that fit an older machine. Not sure when they changed to fixed.

I put a power tip on the exhaust and a pod filter so I had to install larger jets or it would run too lean.

Take note, that IS an air screw, not a fuel screw.

Always a good idea to check valve clearance as well.

I looked at it today and I tried to get some needle nose pliers in there to get it out but I couldn't get it to budge. So is it okay to just cut through to the screw or how does that work?

Take note, that IS an air screw, not a fuel screw.

Always a good idea to check valve clearance as well.

Are you sure it's an air screw? Engine side almost always means fuel screw.

That bike is the easiest bike on earth to adjust valves on, takes like 5 min tops

I would recommend same as Hondaracer, dremel disc cut a slot and if you slot into the surrounding carb body - no real harm.  Don't drill it out, that will be a huge mess and the carb body  is too soft.

 

Cut the slot, spray some liquid wrench or similar in there to loosen, and try to back it out.

 

Also, very typically a lean scenario on these 70s is not resolved with air screw adjustment.  (unless it's radically out of place).  These motors seem to be insensitive to air screw position.  I'd also agree that valve adjustment is something to confirm.  Then, of course air cleaner clean.  Check for correct plug type/heat range. Check if fuel filter, that its not clogged. Leak in rubber boot can cause lean condition. If lean is more on the bottom end (like stumbles off idle),  pilot is more suspect.

 

I know, pretty common stuff but I can't tell you how many times I jump to my conclusion of the problem before checking the fundamentals.

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