TOPIC:

Hi all,

I have decided to look into my carburetors to maximize performance. The carbs have never been re-jetted to a different size. I have needles that came with a kit that have notches in them so I will be putting those in soon. I am not going to replace the pilot jet. My question is what sizes should I look at for the main jets? I will provide information below.

Bike: 1980 Kz 550. Stock pipes, airbox, etc. No modifications.
Altitude: Denver, Colorado (5,280 feet) up to 9,000 ish feet in the mountains.
Stock main Jet: 92
Desire: I would like the bike to run well from the normal elevation up to ~8000 I understand that I will lose performance regardless ascending those higher roads so I am not as concerned about making it run perfect everywhere.
Thought: Order main jet sizes 90 and 87.5 and try them out.

I want to ask y'alls opinions to see if you think I am starting with good sizes or if I should consider even smaller jets. Thanks in advance!

Sorry I don't have much info about running at high altitude. But you should check the Tk22 website to make sure you don't have a counterfeit kit with bad needles. The bad needles run super rich at all clip settings, so that would be the opposite of what you need.

My initial guess would be to run the stock needles and run either of the smaller mains you are thinking of getting. Then simply adjust the air-screws a bit more open as necessary to get a good idle.

You want to introduce the fewest variables possible.

Sorry if I already posted this info below on one of your other threads. It's hard to remember every post.

Here's a link to identifying the bad rebuild kits:
s3.amazonaws.com/gpzweb/TK22mainPage/TK2...TK22rebuildKits.html

This link shows the bad needles in more detail:
s3.amazonaws.com/gpzweb/TK22mainPage/TK2...K22threeNeedles.html

This is the TK22 site's home page:
s3.amazonaws.com/gpzweb/TK22mainPage/TK22mainPage.html

If this bike is new to you, definitely read the valve train warning in my signature before opening the valve cover.

Yes, I have read your timing warning link many times. It is extremely helpful.

Thank you for the information. It is useful per usual.

Here is the kit I am going to buy. I wish I saw this from the beginning but it seems to consolidate everything I need into one kit.

www.z1enterprises.com/keyster-premium-ne...kz550-1980-1983.html

If it really has all those jets, then that is a very comprehensive kit.
I notice it combines the jet holder and needle jet into one piece so it must be a newly designed kit.

The older Keyster kits were of very high quality and the needles were the same taper as stock, were adjustable, and worked well.

Hopefully this new kit is of the same quality. If it is the same company as the old Keyster then I would think it should be.

My only concern, in general, not in your case, is that the pilots take a pretty big jump from 32 to 38. I would have liked to have seen a 35 in there.

K1 claims they are from Keyester am I am inclined to believe them. It seems like an okay risk to me.

You concern is interesting. I am not planning on replacing the pilots so the jump is alright with me.


Also, you seem quite knowledgeable and I am wondering if you have some words of wisdom for using feeler gauges... I just made a new post here
www.kzrider.com/forum/2-engine/612547-using-a-feeler-gauge-help