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TOPIC: Prinzy carb help

Prinzy carb help 13 Jun 2019 22:03 #21

  • Mothersbaugh
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That was my determination. Thanks for the second. And the third.

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Prinzy carb help 14 Jun 2019 05:26 #22

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Wow you’ve been busy. Thank you. So what’s the deal with the different pilot jets? That part was confusing me. It had that long one in it from the beginning then I open the kit n see this little one what gives generic kit or something?

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Prinzy carb help 14 Jun 2019 05:46 #23

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I have no idea what the PO was thinking when (s)he put that huge pilot in there. It is a #45, and the manual calls for a #25...nearly twice as big as it needs/wants. The #25 is standard, and that is the proper size (small, medium, large) that that carb uses. If the carb works for you when it gets back, great. If not, I'd get a real Yamaha/Mukuni jet in that size (#25), No. 1 in this diagram.
www.partzilla.com/catalog/yamaha/motorcycle/1973/ct3/carburetor
The nozzle (No. 4 in the diagram) in your carb is correct, but the needle (No. 14 in the diagram) is not correct in your carb, nor is the needle from the carb kit. I'd buy a new needle as well, if the bike doesn't run well.
Real parts from Yamaha and Mikuni are the way to go; the Keyster kits...you never know what's in them.
I sent it off yesterday. Should be there Monday. Hopefully, you'll be in business.

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Prinzy carb help 24 Jun 2019 21:07 #24

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The continuing saga of Prinzy's carb. He reports back:
Well I got it on and the issue of leaning it from side to side and dying is gone but it won’t idle without choke and if I try to give it any gas at all it dies if I slam it to wide open it runs good but when it comes down I’ll just die no matter what I do. Pilot circuit plugged with a loose piece of crap from the cleaning you think?

My answer:
No. I think the needle is the problem. Neither the original nor the Keyster replacement was the right one. The correct needle is part number 152-14116-10-00 ( www.partzilla.com/catalog/yamaha/motorcycle/1973/ct3/carburetor ), #14 in the diagram, and it's still available from Yamaha. If it runs well slammed WOT, then the main must be good. Did you adjust the carb idle screw and the air screw after you mounted it? Let it warm up enough to get the engine up to temperature? It may run enough if up to temp to adjust those two screws. But when you start to open the throttle, the needle is what's coming on next, until the main comes on much higher up in the throttle opening. The pilot (25) that's in it should allow you to get it to idle with those two screws, even if the needle is wrong, I would think. Maybe MarkT can help us out, here.

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Last Edit: by Mothersbaugh.

Prinzy carb help 25 Jun 2019 00:04 #25

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JetsRus has complete (for my type169 on 250 and about all others as well) needle jets chart of rich to lean, and specific locations to measure needles, very good info. My Kyster kit's needle measured perfectly to the 5DP7 (3 stage) needle I needed to go with the N-8 NJ I ordered to up date a '70 spec carb to DT3 (motor on my DT1c) spec. NJ was 16 bucks & 6.99 ship fee, came a day late @ 4days. Will install tomorrow, got it todays mail. The site is very usefull, I used a similar site years ago to fine tune shit when I had the time & energy to do so. Gettin' older ain't for pussys (a girlfriends mother told me!

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