High-pitched chirpping sound

[madjack56]

Ok. So my 1976 XS650C runs like a Swiss watch. Mike's XS big fin cylinders and pistons, electronic ignition, new electrical system, everything. Plenty of power and starts and runs beautifully. It has the stock Mikuni carbs with new sliders and diaphragms, new needles/seats, and new jets. Tuned and jetted perfectly for this altitude (5,000 ft +). Only thing is, I have a chirpping sound coming from the area of the RH carb. I know that sounds crazy, but I swear that it's coming from that spot. I can find no air leaks and everything mechanical appears fine. Anyone out there ever experienced this before?

 

[NONclow]

Does it chirp only at idle, or elsewhere? How are the carb boots? How many miles on your rebuild? Have you retorqued the head nuts/bolts?

Check this thread out: http://www.xs650.com/forum/showthread.php?t=23162

 

[retiredgentleman]

You have air inleakage around the carb area. They are hard to find sometimes. It could be the seals on the throttle plate shaft (butterflys). It also could be a loose screw on the side of the carbs.

It may be the intake boots. I had bought intake boots from Mikesxs, but found they were a very poor fit, allowing an air leak. Put my 35 year old original boots back in and they work perfect. Mikesxs rubber boots are not made to the correct size, whereas the stock boots are precision sized.

There are many threads on this topic. Use Google Search .............upper left corner.

 

[madjack56]

I'll look for an intake leak. I thought this might be the culprit. Only 1500 miles on the engine since rebuild.

 

[madjack56]

So, I started her up and let her get good and warm. The chirp was still there in the area of the RH carb. I sprayed a little Simple Green around the joint between the carb and the rubber intake manifold and the chirp immediately stopped. I repositioned the clamp and screwed it down tight. No more chirp!

 

[coughing skunk]

I had the same issue. Mine was due to the tubing that connected my carbs to my billet carb holders. The vibrations from the motor were making the carb shake up and down just enough to make the tube move and chirp. I greased the inside of the tube and stuck her back on and the chirp went away.

Note that your chirp will likely come back as the Simple Green only wetted the surface that was chirping for the time being.