KZ550 Main Jet Size Advice Needed!

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.

crown_vick wrote:

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.

Thanks loud, your help is much appreciated. I have rebuild kite en route, but will it the shop for the other jets.

Anyone else on here running a similar set up? (Headers and pod filters)

I'm running the same, pods, headers and a slip-on. But i still have the stock jets so it doesn't run too well.

Well, as luck would have it, the stock carb kits I ordered never shipped, so I was refunded via PayPal. So, now I am looking for 550 carb kits with the larger jets. Does anyone know where or who to order the carb kits from?

These don't have the larger jets, but they have the needles.
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

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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=

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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.

Hmm... I'm going to need more info on you drilling them out, specifically what size bit to use. Dont have a small drill index at my disposal

+1 on the drilling procedure. The bike has been sitting for 7 years, so I am doing rebuilds. Luckily, the local bike shop said they would do the ultrasonic cleaner for me, so that is a huge help. I'll go with the stock kits and drill them.

No eBay APP ID and/or Cert ID defined in Kunena configurationHere's the kit I use. (Ignore the bit vise.)



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.

loud,
you're officially the man. Thanks for the help.

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!

tooocool49723 wrote:

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.