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Discussion Starter #1
Working on fine tuning my carb, WOT it goes flat, but if I swing the choke up I can tune out the flat spot as I am riding. Tells me I’m lean, if I understand what Ive read correctly. Problem is the needle clip all the way down it’s so rich it won’t start or idle And if it does start it’s pumping out I burned fuel.

the needle in the carb has markings that appear to say 05303.

in my rebuild kit I purchased the needed is marked D334.

is the needle in the carb now incorrect or are the just different manufacturers marking codes?

thanks all
 

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I haven’t seen a needle marked D334 before so I am assuming it is likely aftermarket. Where did you buy the jet kit from?
 

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Well a google search shows reveals that needle seems to come in quite a few different after market carb rebuild kits. Needles are super easy to swap out. I say run it and if you don’t like simply put he OEM needle back in.
 

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You tune WOT with the main jet, not with your needle and choke. Needle is (mainly) for pickup and middle.
 

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Put your needle back in the middle and buy the next two size mains. Your needle is for mostly for mid range on 4 strokes.
 

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Discussion Starter #7
This is a huge help thanks guys. Explains what I experienced when playing with the needle last night and why I still had the same issue at WOT.

i will go get thee next size jets. Is there a go to source for them that you all use. Mine seems to just press in not screw in like some I have seen.
 

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This is a huge help thanks guys. Explains what I experienced when playing with the needle last night and why I still had the same issue at WOT.

i will go get thee next size jets. Is there a go to source for them that you all use. Mine seems to just press in not screw in like some I have seen.
Press in? thats wild i have never seen that before. If you can find genuine jets for whatever carb it is then thats the best route but if you end up buying from ebay or other sources just make sure you compare the hole sizes to one another by holding them up to a light. I have had ebay and other company's jets that are not scaled the same (ex. Ebay #185 main jet was smaller hole than another company's #175 so i was having wrong results.) Just something to look out for and will save the frustration if it was to happen.
 

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Discussion Starter #9 (Edited)
It appears the K3 and K5 had this style, Keihin 655a, that just have an o-ring around the. You can see it in this picture middle of the screen below the steel colored spring.

272850
 

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Discussion Starter #10
So I have contacted TB, CHP, NEVC and waiting DRATV to respond. I also called Keihin how directed me to SUDCO who said they don’t have them as KEIHIN made these special for Honda. Waiting to hear from JETSRUS but per their site they have none. Seems this was an odd ball carb on the 72-75 and has no support for jets. All the others I can find jets for. May have to buy a jet drill set and drill it out.
 

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Discussion Starter #11
Okay JETSRUS got back to me and they do not have them either. I was able to get a couple of 58s from CSM. No clue on how long that will take to get here so in the meantime no WOT pulls. If that’s not large enough I will have a local shop open up the second 58 or perhaps the 55 that came in my rebuilt.

The Retailers that support the Z50 clearly have a source as all of their rebuild kits come with new 55 main jets, perhaps if they are on here and see this they could work with them on getting a kit made with a 58 and 60 the K3-K5 carbs.
 

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Discussion Starter #13
I have not played with jets in a long time. On my cars I plug the laptop in and tune them that way, same with my road bike. It's like learning all over again and it seems every carb is a little different in how you tune them.
 

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Have you considered using a '80-'99 Z50R or '00-'06 XR/CRF50 carb? They have readily available main jets that thread in, and will look "period correct" for your '72.

You should still be able to use the stock manifold with the 35mm carb mounting holes and the stock airbox with the 1" opening on any of the above mentioned carbs.
 

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Discussion Starter #15
I actually had that in my mind as an option. since I sourced a 58 and I may have just found a 60 I’m going to try these. If the 60 falls through I can have one drilled out a little. If the jets fail to work that may be the way I go For the reasons you mentioned.
 

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Discussion Starter #16
#60 jet came through. Should have that this week. May put that in and see if it is too rich since the #58 is going to be a while.
 

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Discussion Starter #17
#60 jet came today DHL shows my CMS order should be here Monday with my #58 jet. Plan is to pull carb tomorrow, disassemble it and run it in my ultrasonic cleaner for a while. Then monday when the #58 jet comes in put that in and give it a try.
 

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Discussion Starter #18
Ran everything through ultrasonic and came out great. New emulsion tube does not fit in carb. 0.05mm larger than stock so just used stock. decided not to wait and tried the #60 jet and overall bike ran better but now she’s rich up top. I think the #58 is going to be the ticket.
 

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Discussion Starter #19
Just want to close this thread out.

Discovered I was missing the round gasket in the bottom of the float bowl. After putting that in and running through the jets again and playing with needle heights I finally have it running the best it has yet. #60 jet with the clip one down from the center slot. I guess you could call that the second slot from the bottom. This is with a K&N air filter and no stinger pipe in the exhaust.

Appreciate the help from you guys.
 
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