air leak or carb issues?

[hldmichsj]

Hi everyone. I've veiwed this site several times, but just joined and this is my first post. I'm having engine issues with my '03 SJ that I'm hoping someone could give me some advice where to start. This is my second year riding it. It ran perfect all last season. I've been out about 6 times this season. I replace the plugs this spring (was winterized – I live in Michigan). The last couple of times out, I’ve noticed surging and erratic power. I looked at the plugs, and the front plug looked fine, but the rear plug had a dark reddish brown inslutaor, was dry, and had pretty substantial ash build up at electrode and threads. I replace the plugs last night, rode for about ½ hr. with mostly low to mid throttle, and same conditions were developing at plugs. Does this sound like a sudden air leak? If so, what is most probable area of leakage? Why does just the rear cylinder look bad? Could it be a clogged jet or issues with the rear carb from sitting over the winter? Group K did a big bore build on it in '05 and it has not been taken apart since then and does not have that many hours on it. Any help would be greatly appreciated. Thank you very much

 

[WAB]

2 things I would check first are plug wires. Take off the plug boots & electrodes and cut the wires back a little.
If that does not do it, pull the carbs and go thour them. Clean the small internalfilters. Also, check to see if you have corrosion inside the carbs where water has been in the gas.

 

[hldmichsj]

2 things I would check first are plug wires. Take off the plug boots & electrodes and cut the wires back a little.
If that does not do it, pull the carbs and go thour them. Clean the small internalfilters. Also, check to see if you have corrosion inside the carbs where water has been in the gas.

Thanks,
I'll start there. Now that you say that, when I pulled the boot off of the good plug, the spring/electrode inside the boot was disconnected from the boot, stuck on the end of the plug. I may need new wires. Thanks for your help.

 

[WAB]

Thanks,
I'll start there. Now that you say that, when I pulled the boot off of the good plug, the spring/electrode inside the boot was disconnected from the boot, stuck on the end of the plug. I may need new wires. Thanks for your help.

That is a very good possibility then.
Yamaha used 2 different kinds of wire for the plug wires tht I have seen. 1 is actually strands of wire, nice and thick, easy to strip the coating back and recrimp the plug cap. Another kind of wire I have seen is crap, like tiny threads coiled inside the wire coating.

Good luck with it and welcome to the site!

 

[Shonuff]

Drop Yamacat a PM for some new MSD boots.