Ultrasonic Cleaner Q's

Hey everybody. I'm rebuilding my carbs and I bought an ultrasonic cleaner to help me in the process. I split open the rack of carbs and stripped everything down to the carb bodies EXCEPT the throttle shafts and butterfly valves and I put one carb body in the cleaner with a simple a simple diluter degreaser for 20 minutes. You wouldn't believe how black that water was afterwards, there's a lot of dirt in these old carbs but man those carbs look really clean. Firstly, is it okay that I left the throttle shaft and butterfly seals on the carb bodies? Secondly, should I continue to use the ultrasonic cleaner on each carb body until the water stays crystal clear or is the murky, black water a by product of ultrasonic cleaning? What temperature should I set the ultrasonic cleaner to. Thanks in advance.

 

What did you use for a solvent?

 

Butyl Carbitol is one of the ingredients in that. Get new throttle shaft seals.

 

Does that mean I have to take the throttle shafts out? What would you suggest I use?

 

The throttle shafts do have to come out.
As to the second question I need more specifics. Are you talking about the solvent, tools, or seals?
In all honesty the throttle shaft seals are good for about 10 years of daily riding. Replacing them on a used bike is prudent regardless of their condition.

 

I've tried taking the screws out connecting the butterfly valve to the throttle shaft and it looks rather weird behind the screw. Like it was smashed. In any case, I can't get those things out. Any suggestions?

 

The screws were peened over at the factory so they would not come loose. Take a file to the backside and cut the peening away.

 

Stuff a pice of wood in the opening to hold the butterflies open while filling.

 

Ugh! This is going to be the never ending carb rebuild. Thanks guys.

 

To my surprise it was pretty easy filing down the screws holding the butterfly valves to the throttle shaft and with a little penetrating fluid and some persuasion the screws came right out. Also surprising was how intact the throttle shaft seals were. They were still flexible and soft. I wasn't having any leaking problems before. Should I just take a chance and not worry about the other 3?

 

Since you have the carburettors stripped down better to replace them now I think.

 

Do it right , do it once .

 

Ok. Another question. Even though they're filed down can I reuse the same butterfly valve screws and use Loctite on them or will I have to buy new screws?

 

I have a few questions about float height differences. In the first pic there are three different floats. The shiny one is from the new carb kit. The one in the middle is from an '86 FJ that I was working on and the third is the original float from the xj900 that I can only assume is the stock float. When I put the float needle in them the the FJ and NEW float have a rubber tip needle in them while the xj900 has the original bare tip needle in it. I want to change the floats to either the new one or the FJ because the xj900 float is all chewed up inside but as you can see they all have different heights. Am I splitting hairs here or do I have to use the same height as the original xj900 float seat and needle?

 

That’s like asking 10 people how to use a cast iron pan, you’ll get 12 responses.

Personally I reuse and loctite them unless damaged or head is stripped.

 

That's exactly what I did and it's fine.

 

Those are the float needle seats. The floats are the big foam things that...well they float.

Use the best set of float needls seats that you have. Use the best set of float needles that you have. Use new o-rings.
After setting the float height you are going to set the fuel level anyway, so the overall length of the float needles won't matter much. You'll be tweaking the float tab anyway.
Setting the fuel levels

 

Hot water aids in Ultrasonic cleaning, maybe 120f or there abouts. I also bought my ultrasonic cleaner specifically for carburetors nothing better IMO.
Simple green is a popular solution. The ultrasonic cleans gun parts very well. mechanical clocks, jewelry, anything requiring detail cleaning. One part Mr. Clean, one part ammonia. and hot water. works well and cheap.
Cheers, 50gary

 

I need help. I have two carburetors that sometimes leaks and sometimes doesn't. I was wet setting all the float heights today getting the level right in that sweet spot and the first three carbs went perfect. I come to the fourth one and I couldn't get the carb to stop leaking. And then all of a sudden the 1st carb starts leaking and the 4th is fine. So, I open them up and can't find a single problem. So I go for it and put them on the bike and now both carbs are leaking and then after I ran them on the carbs they both stop leaking. Why am I getting this on again off again leak problem?

 

I share your frustration, seen similar stubborn floats.
You can try tapping the bowls as you fill them.
Shut off the fuel source and drain the bowls each time.
Try raising the fuel source to increase head pressure on the floats.

 

the tab on the float can't have any nicks or scratches on it or the pin on the needle might get stuck on it sometimes

 

Before putting the carbs back on the bike I checked all four carbs for leaks and all were fine. I put them on the bike and now there's leaks galore! The 1, 3, an4 carb all leak and I wasn't even having an issue with the 3rd carb at all. For such a simple system it causes me more problems. It seems like this is something that should work 99% of the time. Ugh. I'm hoping at this point that if I ride the bike all the bumps in the road will wiggle those floats enough to keep them working properly.

 

One other thought is the replacement float needle valves need to be the same length as the original or it changes the geometry between the needle valve and float tang, which results in side pressure on the float needle valve and intermittent operation.

 

Rooster, please look at a couple posts back where I asked about this very thing. I posted pics with the different measurements of the valve seats with the needle valve in it. I would love to hear your thoughts.

 

Which ones did you go with? They look really close, I think the issues were with float needle valves that were approximately 1mm longer.

 

I went with the shiny new ones. If you'll notice the shiny new ones are 19.41mm and the original xj900 float seat and needle is 19.14. Do you think 0.27mm would make that much of a difference?