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KZ550 Main Jet Size Advice Needed!
- crown_vick
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- loudhvx
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Ok, so I bought a 550 at a great deal, and have completely stripped it down to the bone and have been building a cafe from the ground up. It's looking great thus far, but I need your guys help on the gas drinkers. I am running the pod filters on each carb and straight headers. A friend of a friend did the same set up and went from the 92 stock jet to a 130, and said it still ran a little lean. Does anyone have a good formula, or should I go 135 or 140 and keep my fingers crossed? Thanks for any help.
I think he is masking the leanness of the idle jet and needle by going overboard with the main jets.
We're talking about a 550A or 550C, correct? That uses TK-22 carbs.
I would go from 32 idle jet to 37 idle jet. Get adjustable needles and set them to 3rd or 4th clip from the top, and I'd start with 100 or 102 mains.
You can get new idle jets, main jets, and adjustable needles in the K&L rebuild kits. You will have to drill the jets unless you can get some individual jets. The Keihin small-head mains should fit, but I don't know of any source for individual idle jets.
1981 KZ550 D1 gpz.
Kz550 valve train warning.
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- crown_vick
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Anyone else on here running a similar set up? (Headers and pod filters)
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- tooocool49723
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'82 KZ550 "Project"
First bike, 30k miles
Ann Arbor, Mi
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- crown_vick
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- loudhvx
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4 kits will run you just over a hundred. you can search
K&L kit 18-2462. They used ot be on ebay cheap, but not anymore.
www.z1enterprises.com/detail.aspx?ID=476
These are not rebuild kits, but come with larger main jets and different needles. They work really well.
Dynojet kit 2305
www.denniskirk.com/jsp/product_catalog/P...in&skuId=171811&mmy=
If you need carb parts, I'd get the rebuild kits and drill the jets. It's easy and cheap.
If you only need to tune it, then the Dynojet kit may be a better choice.
Or you can just drill the jets you have.
Or you can search for small-head Keihin jets.
But any of those choices won't get you bigger pilot jets which I often find is needed. I drill them myself.
1981 KZ550 D1 gpz.
Kz550 valve train warning.
Other links.
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- tooocool49723
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'82 KZ550 "Project"
First bike, 30k miles
Ann Arbor, Mi
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- crown_vick
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- loudhvx
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Then I use the cheapo "Tool Shop" drill from Menards. It's like $15 or so. It's chuck closes all the way down to zero and there is a really good speed control on it.
I just mount the drill gently in a vise and hold the jet in my fingers. Remember, the hole is already there for the most part. You are just shaving a little more off.
This has worked wonders for idle and off-idle smoothness and popping issues. Drill the pilot jet to 37 (up from 32).
#37 jet is #79 drill bit which is .0145 inch.
That drill kit will only get you up to #99 on the mains, though, so if you want bigger you'll need to source a #60 bit which jet size 102. Or #59 bit which is jet size 104.
#58 is 107. #59 is 109.
1981 KZ550 D1 gpz.
Kz550 valve train warning.
Other links.
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- crown_vick
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you're officially the man. Thanks for the help.
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- tooocool49723
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But they didn't do the primary's. Runs much better at idle and low-throttle now! and I dont have to go around at half-choke anymore! Much improved!
'82 KZ550 "Project"
First bike, 30k miles
Ann Arbor, Mi
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- loudhvx
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Got all my drill bits set, got the carbs off, started going at it only to find that someone had already drilled out my mains!!!
But they didn't do the primary's. Runs much better at idle and low-throttle now! and I dont have to go around at half-choke anymore! Much improved!
Cool. Don't forget to reset the Air screws. If you haven't already, a good starting point is 1-1/4 turn out. You should be somewhere from 1 to 1-1/2 out, I think.
1981 KZ550 D1 gpz.
Kz550 valve train warning.
Other links.
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