Xt550 Build

Alright Guys, this is my official thread for my Xt350 build with the kz550 engine. Hopefully it is a fairly simple build. I will be documenting it as I go. Starting with my into in this Youtube Video ()

Welcome aboard. It looks like a huge project to me, so take your time. Consider the fact that the weight of the whole XT350 bike was originally about 265 pounds and the KZ550 engine you plan to install weighs about 155 pounds; this would suggest that some frame bracing and suspension changes might be prudent.

The brass tubes on the carb holders are vacuum ports. These are the attachment points for vacuum gauges when synchronizing the 4 carbs. During normal operation they need to have rubber vacuum caps over them to prevent vacuum leaks. Speaking of carbs, since you plan to use pods rather than an airbox on those CV carbs you will need to go through the tedious drill of trying to find the magic formula for re-jetting the carbs. I suggest you use the "search" function on this site - just key in the word "pods" and you'll find 860 postings for the past 12 months and 6,813 earlier postings on the subject. There's a lot to learn, so prepare to become a carb expert.

Good luck with your project. Ed

It depends on which 1982 motor you have, as to what carbs you can run.

If the motor says Kz550A....... then the motor will use the Tk22 carbs, which are manual slide, and tune well without an airbox. That is what the motor looks like. You have a set of TK22 carbs on the bench, upper left side in the video. The pod filters for those will be smaller than the ones for the other, CV carbs you have there.

If the motor says Kz550D...... then it is a Gpz motor and uses Tk26 CV carbs. But the motor would have been all black and had a more angular look similar to your Spectre. (Also would have had oil cooler.)

You can't put Tk26 or Tk27 CV carbs on the earlier motors which came with the Tk22 carbs because the manifold bolt spacing is too tight.

My signature has links to Tk22 info, and a lot of Kz550 info. Read the valve train warning before doing anything with the valve covers.

@650 Thank you for the carb info. Have done the carbs on the 750 many times, if it comes down to it I will buy a jet kit and go hog wild As for the suspension, I know the rear spring on the monoshock is adjustable, would stiffening that be enough do you think? I am a fairly avg. rider weight at 165 lbs if that factors in at all.

@hvx I have looked at some of your stuff in the past few days, I am confident in my clymer manual and the communities knowledge, The biggest fear I have at this point is going to be the wiring. I am good with the engine mounts because i can cnc plamsa cut some at my school (home of the first high school chopper class). Frame bracing is going to be another issue for me, the only issue is going to be where to brace it at? I really don't feel like putting my mind on making the force vector charts to do so, that would be a lot of trig and with my class/work load i am pretty stretched thin.

I looked and the motor is the kz550 A motor. I do have a question though, I have once IC ignitor, I am missing the ignition control unit (I believe) Unless it is the Ic Ignitor. Then I am fine. Will I have any issue with editing out certain functions? (I.E. hazzards)

Racewayelko wrote: I looked and the motor is the kz750 A motor. I do have a question though, I have once IC ignitor, I am missing the ignition control unit (I believe) Unless it is the Ic Ignitor. Then I am fine. Will I have any issue with editing out certain functions? (I.E. hazzards)

What's a 750 A? Ed

650ed wrote:

Racewayelko wrote: I looked and the motor is the kz750 A motor. I do have a question though, I have once IC ignitor, I am missing the ignition control unit (I believe) Unless it is the Ic Ignitor. Then I am fine. Will I have any issue with editing out certain functions? (I.E. hazzards)

What's a 750 A? Ed

bwahaha sorry about that :facepalm: long day at work It is the 550 a motor I am so used to typing kz550-n1 from my spectre that it is muscle memory. you think I will have an issue with those slide carbs? I suppose I will have to play with the a/f mix. I do know from previous owner that he was having trouble with the #1 cyl. something to look at when I get it running though

The IC ignitor controls the ignition.

I don't think the KZ550A has a hazard function, but if it does, it won't be related to the ignition.

The slide carbs will work fine once they are jetted properly. If the motor had issues, you will want to do a compression test and leakdown test, and check the valve lash.

What do you guess I will have to go up on jets? 5 sizes over stock or is that a bit much?

Also, is there a kickstart that I could put on? I trust my legs more than I do the electrical lol I like riding in cold weather and I can kick longer than the battery can turn the starter CHeers

Racewayelko wrote: What do you guess I will have to go up on jets? 5 sizes over stock or is that a bit much?

Also, is there a kickstart that I could put on? I trust my legs more than I do the electrical lol I like riding in cold weather and I can kick longer than the battery can turn the starter CHeers

I don't think there was ever a kickstart option on the Kz400-4 / Kz500 / Kz550 / Zx550 / Zr550 line of motors. They are pretty easy to bumpstart, though.

Stock jetting had 92 mains, 32 pilots, and the needle was clipped at the equivalent of the second groove down from the top on the adjustable needles. You can get adjustable needles in most rebuild kits.

With pods and a 4-into-1 pipe, I would start with
96 mains. Might go up to 98.
34 pilots. Will likely go up to 37.
4D93 needles at 3rd clip (middle clip).
Air screws at 1-1/2 out.

Okay.. So I have some major decisions. my soon to be step father is the one who gave the motor to me has the original bike the motor came with that he stuck a gpz550 motor in that is known to run but has a carb issue with the #1 cyl. I checked and the pod filters are made for the gpz carbs so it would work better with this project. Found out the Kz550 engine has a knock and I have the head open anyways so I checked and they are all within clearance so it will be a bottom end knock. Is there anything that is known to go with these motors? I also notices that the top caps (from front and right to left) go 1, 2, 3, 4,
6, 5, 7, 8,
So I don't know what that is about you would think they would go in order. But back to the meaning on this post, should I put the gpz motor in xt frame and return the kz550 to stock and fix the motor from there? Everyones thoughts?

Those cam caps should be in order. Notice 4 out of 8 have thrust surfaces. Those keep the camshafts aligned with the chain. With the caps in the wrong order, the cam can move where it's not suppoed to.

Also, you can't mix and match caps from motor to motor. they are machined in place on one motor, and should stay with that motor in the correct position. If you are lucky, sometimes you can find ones from another motor that will work. basically you put the caps in place without the camshaft and try to feel if there is a ridge where the caps meet the head, in the opening where the cam journal would be.