YICS Passage clean out

OK. I used the stainless wire brush I got from Chacal. After running it in and out of each of the passage sides about 10 times, it was pretty clean. Still had a few specs in the passage so I used compressed air to blow it out. The passage sealing bolt on the opposite side was removed so the air could blow the specs out the other side. It worked well. Put the new sealing washers on and torqued the bolts to specs. Now I have a low to midrange miss until the engine gets good and hot. And then if I drop the rpm's down below 4K, it will miss some climbing back up. I'm wondering if some of the air blew back toward the carbs and maybe took some debris with it. I guess I'm going to have to pull the carbs tonight and tear them down to see if I can find anything wrong. I did pull the plugs. #1 & #2 were fine, #3 & #4 were looking a little rich. All plugs were great and bike ran fine before passage cleaning.

Valves adjusted 2 weeks ago and YICS passaage blocking tool used during synchronizing after the passage was cleaned.

Any thoughts on this problem?

 

The passage has holes that go up to the intake runners. Maybe some carbon got stuck in one or two of those. I don't like to advise to pull the carb manifolds but not sure how else you could get at them.

MN

 

Why not pull a vacuum from one side of the YICS port?
You could use your YICS tool to block off 3, to pull a vacuum on 1 of the end ports, then back it out enough to pull on 2 from one side then flip it to the other side and repeat the process. You should be able to pull most anything out you may have blown up into the ports.

 

The vacuum idea sounds like a good one. I pulled the #1 intake manifold off to try to see where the small hole is going to the passage, but was unable to find it. I have one of those small dental mirrors that I might be able to use to see down around the bend going towards the valve stem.

I dissasembled # 3 and #4 carbs to see if any debris went back into the carbs, but found nothing.

Thanks again guys