Topic: Cleaning slow jets, any risk to damaging the inner bore?

[fizzlebottom]

My bike has the stock Keihin #35 screw-in slow jets. I'm doing a preliminary mid-winter cleaning just cause I let some #$%* gas sit too long. Etc, etc.

I play guitar so I usually just use part of a guitar string to whip through the jets and make sure there's no stuck debris. According to whatever internet sources, Keihin jet sizing would mean that a #35 jet = .35mm = .01377in. The guitar string I used is .013in, measured with digital calipers. There was definitely some resistance going through every jet and even when cleared, the string does not slide effortlessly through each jet. They move, but not on their own accord. I can see daylight through each one, so they are as clear as they can get.

My concern is that pushing the string through each jet may have scratched the ever living heck out of the interior bores. I don't know if that surely is the case, and I don't know if any potential interior damage will change how they operate. In the meantime, I ordered a fresh set of genuine Keihin #35 jets from Jets R Us.

But what are your thoughts around any issues with the original jets?

[grcamna2]

I've used a guitar string before and I lightly file the sharp edges of the guitar string to ease the use of it while I insert it into the small jets.

[Kelly E]

Compared to the soft brass jet the guitar string is very hard. When you cut the guitar string You create a chisel point which will easily enlarge the brass jet.
A carb guy I know has a bin full of jets that were cleaned with a guitar string and are now oversized.

[fizzlebottom]

Compared to the soft brass jet the guitar string is very hard. When you cut the guitar string You create a chisel point which will easily enlarge the brass jet.
A carb guy I know has a bin full of jets that were cleaned with a guitar string and are now oversized.

That matches what I think probably happened with mine. New Keihin brass on the way. I'll keep the originals in a bin in case of ... something.

[BenelliSEI]

Don’t put anything through them. Even a scratch will alter them. Carb cleaner soak and then I put them in a small ultrasonic tank. Blow dry with high pressure air.

[Deltarider]

I've never been tempted to use any material harder than brass. My instrumenet has always been some stranded copper wire, which is supposed to be softer than brass. So far no problems.

[Deltarider]

Warning! Some thought to have seen a 'gauze' or some sort of web inside the bore of the slow jet. There isn't any. Please read: http://www.sohc.co.uk/index.php/topic,22417.msg204301.html#msg204301 and the following replies.

[rotortiller]

Just clean very gently, remember there is a difference between scratching your hole and tearing it apart. 

[dave500]

soak your brass in vinegar,it wont eat it away,itll clear any corrosion and brighten them up nicely,ive left brass for days in the stuff.

[fizzlebottom]

soak your brass in vinegar,it wont eat it away,itll clear any corrosion and brighten them up nicely,ive left brass for days in the stuff.

From now on, yes. No more mechanical object removal. I hadn't seen a cutaway image like shown above either, which really goes to show how dang small the orifice can get.

[rotortiller]

The good thing about the idle (slow or pilot) jets is that they are adjustable through pilot or mixture screws after cleaning. That said makes it less critical to minute damage.

[grcamna2]

The good thing about the idle (slow or pilot) jets is that they are adjustable through pilot or mixture screws after cleaning. That said makes it less critical to minute damage.

Yes indeed ! 

I keep hoping to own/work-on bikes that haven't had their pilot/mixture screws jambed-shut,rather than lightly seated with a gentle hand.    Less is better.
I have removed pilot screw plugs from 80's carburetors which needed to have the blind-plugs which cover them lightly drilled out,then a screw threaded in to the plug(not the screw underneath! be careful)to pull/remove them out with a small pr. of Vise Grips to gain access to adjust them.
I found a number of times,that one pilot screw was completely closed.. From The Factory !!
Pissed me off.

[dave500]

guitar string is fine just take care,gas welding tip cleaners are a big no no though very tempting!

[Hibees32]

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[Don R]

 Hey, you guys been watching me? These are all the things you've been telling me to do for years. HA!