Persistence pays off!

So, I spent the last week trying to "dial in" my bike. We (my son and I) just rebuilt the carbs (complete except floats), checked the valves (all in spec), set the cam chain tension, wet set, bench synch, and dynamic synched the bike. The only thing that was left to dial in was the air/fuel mixtures. We set the bench mixtures at 2 3/4 turns out initially. Well, no matter what I did I couldn't get rid of (a) a bit of loping and (b) rich plug in #3. So, I broke down and bought a ColorTune. #1 went well; #2 went well; but, when I got to #3 I had to turn the pilot screw almost all the way in (1/4 turn out) to get it to lean out enough!!! At first, I thought that maybe I botched the wet set and #3 was flooding - but that didn't make sense as there were no other signs of that. I knew the air box was fresh and clear (part of work we did). So, I thought that maybe when my son put in the new pilot screws that he didn't get the old o-ring or washer out - or, maybe he put them in the wrong order. Sooo... I pulled the pilot screw out (which is a chore in-and-of itself when the rack in mounted - ended up grinding down a pair of needle nose to do the trick). ANYWAY, this is what came out. Eureka - problem found!

 

Is the fine tip of the screw stuck down in the carb?

 

Please explain for the carb tuning novices........like me.

 

Take a look at an undamaged pilot screw (has a red line drawn around the components in the first pic...)

http://xjbikes.com/Forums/viewtopic/t=31061.html

 

RE: where was the tip

So you may have read that when you bottom out the pilot screws (before then backing them out 3 turns) that you should no overtighten. I believe it is usually written like this:

DO NOT OVERTIGHTEN!!!!

These pilot screws are made from soft metal. It does not take much force to shear off the tip. So, apparently when either I or my son bench set the pilot screws one of us tightened it down to far - which caused the tip to shear off.

I had to remove the rack to get the tip out of the bore. I then replaced the pilot screw and now I am tuned up beautifully!!

 

hmmm. looks like you're missing a little something!