Brass Ball(s)

[LC Cnd]

Does one replace both brass balls or just the 4.5mm one to properly clean the passages?

IMG_4144.JPG (115.62 KiB) Viewed 1946 times

[wolfeman28]

Big one. Small one is simply the plug for the pilot airway machined hole

[JonW]

http://www.aircooledrdclub.com/smf/inde ... ic=53917.0

[tacky1]

I reuse the brass ball. Just drill it half way and use a stud extractor or a coarse screw to pull it out. Reuse with a little thread lock

[kobra]

So this passage is only for the air screw passage, correct? Where is the other end of the hole?

[RZ350Street]

I drilled one of my carbs out last night. The large brass ball hides a passageway with a few outlets. First it meets a passageway to the vent line on the side of the carb. Past that it goes through a brass "jet" that restricts airflow and it has an opening into the top of the float bowl. Finally, it feeds air to the emulsion tube above the main jet. I attached a diagram to try and convey it better because the wording is difficult.

The small brass ball covers the passageway where the pilot air screw ends. Air flows in via the open hole, past the pilot air screw into the passageway behind the small brass ball. From there I'm a little hazy on the routing but it connects to the small holes in the bottom of the carb venturi on the engine side of the throttle slide. The pilot jet passage also 'T's in there.

Kevin

[LC Cnd]

Appreciate the diagram Kevin. So, just squirt a little carb cleaner past were the large brass ball sits to clear the passages should do it correct? Heard that marine carbs (perhaps Yamaha) use brass balls - hopefully ck a local marine shop will have the 4.5mm balls in stock or can order them. Don't fancy having to purchase 50 pair on Ebay.

[RZ350Street]

Honestly, I would try blowing through the passageway by mouth before I removed the ball. I only drilled out one carb, once I understood what was going on I was able to test the second by blowing through it.

This is what I would do:
Remove carb from bike.
Remove main and needle jet.
Plug the opening where the needle jet opens into the venturi and blow into where the main jet would normally be.
You should get air coming out two places, 1. A hole in the top of the float bowl chamber near the 'tower' where the needle jet lives. 2. The external vent on the side of the carb.
It takes a bit of finger work but you should be able to alternately plug each of the holes and make sure air flows out of each of them. If air flow resistance is the same on both carbs I wouldn't pull the balls myself.

I worked in aircraft maintenance for a bit, and drilling these balls out without a clear need is a risk for "maintenance induced failure". I was concerned about damaging the carb body while drilling the ball, and mine was not nearly as easy to remove as others made it sound. Also, I had introduced a bunch of little brass drill shavings that I then fought for a bit to ensure they were clear of all the little nooks and crannies.

Kevin

[LC Cnd]

Sound advise Kevin - be doing that test tonight! Gotta admire someone willing to drive an RD/RZ in your neighbourhood - suspect you're scrapping the helmet visor/headlight of pesky bugs every time you ride day or night. Of course if you drive in circles the expansion chambers will help lol. Cheers Scott.

[tacky1]

I don’t know how you found it so difficult. I have drilled multiple sets of carbs, drill in a couple of mm and pull out the ball. Simple. Reuse the ball so you don’t need to buy 50 of them.
Some of the carbs I drilled were clear, some were solid blocked. Had to “poke” them to clear them.

All we are doing here is trying to get your bike running properly and this air circuit is usually a running problem on the LC.

[RZ350Street]

How did you pull them?

My experience was definitely not that smooth. I tried to drill in a couple mm and remove the ball using screw extractors.

Unfortunately, that ball was solidly wedged in there and the screw extractor just mushed the soft brass. I ended up having to drill all the way through and fortunately the drill bit grabbed at the end and spun the ball, breaking the bond and allowing me to pull it out.

Kevin

[wolfeman28]

Mine came out by drilling a tiny pilot hole, then fitted an extractor with about a quarter turn and it pulled out instantly. Did it like that on 2 sets of carbs.

I also do not replace the balls. I have noticed no difference with them out, other than easier access to clean them.

[pdxjim]

Lots of info here: http://rdlccrazy.proboards.com/thread/4 ... dification

But on further reflection, maybe this is a totally different issue regarding the 4L0-00 carbs only.

[LC Cnd]

Completed the air test as suggested. Noted one of the passages/vents (blocked by the screws) barely allowed air through. Would it be advisable to squirt carb cleaner into the restricted vent 1st before attempting to remove the brass ball?

[LC Cnd]

Took the carb to a Yamaha mechanic (working on 2strokes since 1980) today for guidance. He advised that the inside top hole that is open is the one closest to the side vent - the opposite hole is block/undrilled as Kevin mentioned. He also advised to spray wd40 down the pilot jet (after removal) to see if that passage ways were block (2 holes closest to hole where the carb needle extends into the carb) - did, not blocked so the all the passages are clear. The mechanic advised H2O/wd40 or breath test 1st, ultra-sonic clean the carb 2nd and drill the brass ball as a last resort. Interestingly ck'd a Canadian brass ball bearing on line company wanted $12 per bearing. Don't think so. You can get 100 for $7 from Asia which is a bit much volume wise. Imagine a form member has extra for sale if needed.