Topic: 71 CB500 carb kit slow jet

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Hello,

I need some help. I purchased 4 new carb kits for my 71 cb500 four and the replacment slow jet, though stilll a 40, is about 1cm shorter than the one that was in the bike. This is from the KL kit for the CB500... I havent fired her up yet but I'm curious if anyone else has run into this. I'm not sure given the float height that the "new" jet will be long enuough to pick up fuel.

Anyone else run into this?

Thanks,
C

[Scott S]

 YES! And it was a major pain in the ....

 I have a thread on here somewhere about a hanging idle problem. I had cleaned the carbs multiple times, synched them over and over, had a pro take a look at them, etc., etc.
 Then, one day I pulled a set of parts carbs out of the junk yard. In it were the stock Keihin jets. I immediately noticed a difference.



 Installed the stock Keihin jets and all my issues went away. Not only are the aftermarket jest shorter, but the emulsion holes are in a different pattern and of a different size.
 You can re-use jets. They rarely, if ever, wear out unless someone's been mucking with them. You can use the gaskets, needle valves and O-rings from the rebuilt kits, but I HIGHLY recommend using the factory jets.

[:c:]

Scott,

This is awful news.. the factory ones are clogged shut and no amount of caustic goop cleaner will get them clean.

Im thinking I'm going to solder a brass extension tube to the end of the jet.

I'll post how things turn out.

Thanks for the info,
C

[Scott S]

 I would try soaking them in some Berrymans carb cleaner and use a guitar string or tip cleaner (like welders use) to try to clear them. I can't imagine that there's build up in there that can't be removed.

 Maybe try a 50/50 mix of Simple Green and boiling water in a small tupperware container. Drop in the jets and let them soak, then try pushing a small wire through them.

[TwoTired]

The old jets can be cleaned.  I've yet to find one that couldn't.  Just use something softer than the brass material to hog out the hole.  The "hogging device"  needs to have a smaller diameter than the .4 mm jet orifice.

I think I read that someone used propane torch to clean them.   But, it will help to be familiar with heat limits to avoid melting the jet. Hot enough to make the deposit crispy, but still below distortion temp.

I have a small crock pot filled with anti freeze the cooks engine deposits off my model airplane engines.  I wonder if it would work on fuel jets, too?

I wouldn't use acidic or basic type cleaners to soak brass (such as simple green), as they remove metal once the surface deposits are gone.  Hard to imagine actually wanting to remove metal from the machine.

[:c:]

I would try soaking them in some Berrymans carb cleaner and use a guitar string or tip cleaner (like welders use) to try to clear them. I can't imagine that there's build up in there that can't be removed.

 Maybe try a 50/50 mix of Simple Green and boiling water in a small tupperware container. Drop in the jets and let them soak, then try pushing a small wire through them.

Good call on the guitar string. I managed 3 of the four this way. I'm a bit worried they aren't 40 anymore but they will be clean. The last one wouldn't give it up so I agitated with the string and they are spending the night in the carbcleaner bath... I will try simple green if this doesnt work.

So did I just buy the wrong set or do they not know the jets don't fit? Also, the inside of the carbs are mangled, pieces chipped off, edges worn, etc... Is this normal or did a monkey rebuild these last time? Does the material become brittle over time?

[Scott S]

 It's not uncommon for the posts the main jets press into to be corroded. As long as the o-ring seats, they should be fine. I'd re-use the stock main jet, too.

 You can see two different aftermarket jets in my pic. One was in the carbs when I got them, the other came in a kit. Even they don't match each other. I didn't know they were wrong until I stumbled upon the Keihin jets.

[:c:]

Flipping thru the pictures it looks like the only slow jet available today is the short one.

I managed to clean the last jet this morning and I'll install them today.

[Scott S]

 Keihin jets are available if you look around. You can also find members from time to time that are parting out carbs.

[Danno]

I use a strand of copper wire and carb clean and a lot of patience you just keep twisting the wire with the jet full of carb clean and it will eventually work through the gunk also copper is softer than steel guitar strings which can damage the jet if you are not careful so can tip reamers that welders use but if you had to choose one use the reamers they are softer than the guitar string

[dave500]

Flipping thru the pictures it looks like the only slow jet available today is the short one.

I managed to clean the last jet this morning and I'll install them today.

the keyster slow jet is the same length as the stock one,dont trust their accuracy though.

[:c:]

Got it rebuilt last night but the float drain orings (probably supposed to be gaskets no?) disintegrated when I pulled the drain plugs. Not in the kit

Anyway here are some pics of the process and showing the mangled insides.

[:c:]

Installed some nitrile o rings on the drains but the bowl gasket from the kit aren't  sealing. I think they are too narrow.

I'm pretty unhappy with the kl carb kit at this point.

I have ordered some liquid gasket to help the seal.

Also discovered that those fat black fuel lines kink no matter how much I trim them.

[TwoTired]

Why don't you use the Honda gasket kits and the proper 5mm Fuel line?

[:c:]

Didn't think it would make a difference. Lesson learned.