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fourex

KT 250 Needle and Needle Jet.

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Hi All,  I would like to replace what I believe is the original 43 yo needle and needle jet in my KT, I have found a NOS needle (5D1/part#16009-066) on ebay but cannot find a needle jet (series 172 O/8 or maybe 0/8) part #16017-087, hard to tell if it's a "O" or "0".

I can see from various Mikuni websites that the outer dimensions of the readily available series 182 needle jet are the same as the Kwaka's series 172 jet, but I don't know if the internal dimensions the same.  IE: Does series 172 O/8 or 0/8 = series 182 O/8 ?

I also realise that if I find a modern day Mikuni Needle Jet that matches the old version that I will also need to upgrade the MJ to a newer style hex type to suit, I believe that the old round 85 MJ is about a 120MJ in the hex version, does this all sound about right ?

Lots of questions I know but I'm in a quandary.

In essence, what have others done in recent years when needing to replace needle and needle jet on these old carbs ?  Cheers.

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There's a reference chart somewhere that gives the hole diameters for Mikuni needle jets. I'll see if I've still got it

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image.png.3dd8c7b51c83d1e97745c77f467cce04.png

Looks like an O is an O for any Mikuni needle jet

Edited by feetupfun
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To answer your other question, the KT carby on my KT is still doing great service. Haven't had to do replace anything in it the 20 years I've been using it.

I'm also running a KT250 carby on my 250 OSSA trials bike and did have to lift the needle a groove compared with standard KT settings to get it to run right.

Edited by feetupfun

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2 hours ago, feetupfun said:

image.png.3dd8c7b51c83d1e97745c77f467cce04.png

Looks like an O is an O for any Mikuni needle jet

Thanks Encyclopaedic Dave, that's useful information that I couldn't previously find but I'm still curious what others have used as substitutes when they couldn't find NOS jetting.

My KT was restored by a previous owner  many years ago and I have kept it in storage since I purchased it about 2 years ago, I only give it a run every few months but lately when it was running rough and then wouldn't start I pulled the carb apart to find the cork style bowl gasket had disintegrated and was clogging everything, just thought whilst it's apart lets replace what I can, new float needle and seat on its way from Robert in NZ but he does not have Jet Needle and Needle Jet. 

I'm thinking I will sell it once it's running properly, previous owner has done a stellar job on the restoration, it's too nice to ride and scratch for my liking. Keep an eye out on Trials Australia and Gumtree Australia in the future if anyone is interested. Pic attached from last week.

 

004.jpg

Edited by fourex
missed a word.
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Hi, the only thing I've done to my Carb is strip and clean, and make a new bowel gasket. My bike had been sitting outside before I got it in 1989, rode it a few times before storing it until 2014. Found some ali corrosion in the airways. bit of a mission to clear but got there. Since cleaning and putting motor in the new frame (see projects) its been faultless. Original bike was pretty rough

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Possibly, take a look at the Sudco companies info or Jets R Us.  The items you are asking about, I would suspect are still available in tne aftermarket

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