Enrichment intermittently working

No idea how this happened, but my enrichment is acting funny right now. I cleaned carbs, bench sync done, valves are in spec, float wet set is good, but enrichment only working when it wants to. When I put everything together after cleaning, enrichment did not work as it should. I had to keep throttle open a little and enrichment open all the way to warm it up. It drained a lot of gas out of tank, but then my engine started to rev as I played with the enrichment. I ran the bike with everything running great, for a day. The next day, I started it up, warmed up with enrichment only and it was fine, until I filled up with gas. Then the enrichment stopped working again. Pulled carbs again to wet set floats and everything was fine. I just don't understand how filling up tank with gas could do this. And also, when I fully engage the enrichment lever, I hear a hissing sound. Does anyone have an idea of what may be going on?

 

Sounds like you have a vacuum leak, spray some carb cleaner in the area of the hissing and if the RPM's increase you found your leak.

 

Try starting the bike with the fuel cap open/removed. You may have a plugged breather port in the cap creating a vacuum situation in the fuel delivery.

Note: You will need to squeeze the slides in on the cap to removed the key.

Ghost

 

Oddly enough, I went out this morning and opened the gas cap and it started right up with enrichment open all the way. After about 20 seconds or so, the rpms started to climb. The enrichment is working again. Now about the vacuum leak. I am going to try and ride for a bit and then shut it off. I will wait for about 20 minutes and see if that changes anything. If it sounds as if I have a leak, i guess I will suspect the intake manifold gaskets, since those are the only things I have not changed. (I didn't want to have the bolts break in the head just yet) It would make since if it leaks there as it expands while heating up.

 

Went back out to the bike and had a hard time starting it. When I first tried, it would die immediately. Then I tried opening the gas cap and starting it. Guess what? It worked. It started and ran like a dream. So I guess you were right Ghost. I have something plugging it up. It sounds about right, since because when I first got the bike, my friend said it sat outside uncovered for almost 2 years. Yes, the bike does not look like much right now, but at least I finally got it running. There was no sign of a vacuum leak, but of course, I am not ruling that out completely. Come this winter, I will finally be changing the gaskets on the manifolds. Thanks a lot for the help. I don't know what I would do without this forum and the many experts.

 

This might help: http://www.xj4ever.com/gas%20cap.pdf

 

Hey thank you very much Fitz. I will be ordering the parts in a little bit.

 

Your whistle noise is from the fuel tank. With the breather plugged in the cap. The tank creates a vacuum. The noise is caused by the air leaking past the cap seal.

Do not mess with the intake boots just yet. Take some RTV sealant, and place a bead of sealant around the boots where they mount to the head. Save the broken bolt removal for the winter.

Ghost

 

Update: I figured out what the problem was. I started another thread for something totally different, but ended up being the same cause for all my problems. One of my cylinders were not firing due to a bad spark plug. This was an intermittent issue. Sometimes it worked and other times it did not. Once I got some new plugs, everything runs great. I will never buy cheap plugs ever again. What was happening was the bad cylinder what just sucking up the gas and flooding. But yeah, the gas cap was an issue. When I took it apart, the seal just crumbled. So, thanks for telling me about the cap. If it wasn't for you all, I would have never checked my gas cap.