Isolating YICS = Lower Idle RPM?

After bench synching the carb by using 1/4 inch strips of business card and installing it back on, the bike rpm was way up in 4000-6000 range until I had to turn the idle knob several times down to 1200 as per manual (remember, mine is 550). It ran beautifully.

However, when I installed a homemade YICS tool into the port, the idle rpm went down about 200-300 rpm below 1000. Barely running.

I had hard time making transition between vacuum tubes using one vacuum gauge. The engine kept stalling on me.

I'm not sure if this is normal whenever the YICS passages are isolated from each other or my YICS tool isn't sealing properly?

Am I supposed to see drip in idle RPM when isolating the passages or was I doing it wrong?

I will try a poor man's YICS tool, aka a soaked rag stuffed into the passage.

 

Could happen cause you've just isolated the carbs that aren't set up correctly.
Just crank the idle up with the YICS tool in place, do your adjustments, remove the tool, and make final adjustments to the idle if needed.

 

Normal.

With the YICS Blocked -- RPM's should fall.

Once you get 'er all dialed-in, nice ... and remove the YICS Tool ... the revs should pop-up some ... and, you just lower the Idle with the Idle Adjust Rod.

Do all the Syncing and Mixture settings with the Tool IN ... Then, when you are ready for people ... pull-out the Tool (or improvised Tool) and make a final adjustment to the Idle with the Idle Rod.

 

Ok, will try those and post the result here...

Thanks

 

Ugh... Just tried the soaked rag thing... Messy!

The rag on the end kept ripping off the coat hanger wire that I used to reel it through. I used the mechanic red rag soaked with olive oil...

Guess somebody will come along and tell me I used the wrong material. Probably a softer cotton or something like that might work better?

Will try again with the homemade YICS tool later... It's in the drawer of my tool cabinet 150 miles away.

 

I think you'd get better results with the tighter weave of a strip of old t-shirt.

Tough to push in with coat hanger. Grab the ramrod off your muzzle loader. Use that.

What? You don't have a muzzle loader? Ok, use a piece of 1/8" threaded rod . Careful using wooden dowel rods, if one of those snaps you could do some serious damage to your hand and/or eyes.

 

T-shirt.
Long thin strip square knotted together.
Best to have and assistant help you.
Stuff to the middle of the passage from both sides.

It's for those who Don't have a YICS Tool and are desperate to get tuned-up.

I never said it wouldn't make a mess.

A Guy from the other site tried it using water. He said it worked fine with water soaked T-shirt.

 

Noted.

The bike runs ok but when in the first gear, it would surge then bounce back in power then repeat the cycle. But once cruising, it rides ok.

Also, when downshifting from high gear (coasting to stop) the rpm would remain at 3000. Even after engaging the clutch and blipping the throttle, it wouldn't come back down.

So I assume all those are due to carbs not being synched.

I am planning on a 300 miles round trip on the bike this weekend. Will riding the bike in this condition harm it?

If so, I will refrain from riding this long and just limit myself to local trips.

Thanks

 

You have a Linkage Problem or your Diaphragm Pistons aren't coming down.

Use the Cable Slack adjuster on the Throttle Cable up near the Handlebar Control and give yourself some slack on that cable.

Check that the Linkage isn't binding.

Check that the Diaphragm Pistons are actually closing when the Throttle is Closed.