newbe asking for help for a buddy!

This is my first post and I'm an old Goldwing rider. I have an 1984 aspencade and I love it. I do all my own work on my wing! Anyway...

My buddy has a 1976 KZ900 in his garage and he asked me if I could get it running for him. It had been sitting for seven years sense his son got killed on a motorcycle. Now his wife wants him to ride it or get rid of it.

It sat with fuel in the carbs. I took the carbs off and got the slides to move with a lot of help from spray can chemicals. Got the jets cleaned up and now I sprayed WD-40 in the cylinders to make sure that the rings and cylinders get some lube. I'll do this about three more times before I try to make it start.

If anyone has any other comments to what I should do to make sure it runs please let me know.

The main reason for this post is that one of the O-rings around the plunger for one of the chokes is torn and needs replaced. He needs to replace both throttle cables and the choke cable.

Where is the best place to find these cables for the best price and does anyone know the size of the O-ring he needs. Can he get just the o-ring or will he have to order the complete pump?

Thanks for all the help you can give this old man and you will be helping another old biker to get back on the road!

PS. I have a set of vacuum guages that I use to sinc the four carbs on my wing. How do I sinc the carbs on this bike? Are three carbs adjustable and one not like on my Wing? Also, What would be the best settings for the fuel/air mixture screws on this bike? I kept them set at the setting they were when I took the carbs apart but they were all set differently. Any help would be appreciated.

Post edited by: longhaireddwb, at: 2007/04/02 22:44

welcome to z-jungle!id try z1 enterprises for the throttle cables,choke cable?choke should be a lever on side of carbs unless someone has modified things.might check wiredgeorges site in links section for carb stuffB)

just my 2cents worth, But you might wanna use some thing like Marvel mystry oil on the pistons as well. I think it gives much better penetration around the rings and will cut the rust as well. As to the Parts.. We have many folks here who are either selling parts or are in the bussines of repairing things like carbs,instruments,ETC. Just ask and look arounf inthe fourms

Like Wireman said, Jeff at www.z1enterprises.com/ is the resident Z1 expert, if he can't get the Z1 parts you need, then I doubt anyone can.

Thanks for the fast response guys. I checked out the web site you gave me and you were right. Great prices and he has what we need. I'll pass this along to my buddy today and have him give them a call.

I didn't think about the MMO in the cylinders instead of WD-40 but I'll tell him that today so he can get some and put it in the cylinders.

If you come up with the O-ring size please let me know. Its the one that goes around the plunger that the choke lever moves up and down on the carbs. I didn't see it listed on that web site.

Thanks again for your help and I'll keep you all posted on how it comes out. Jerry...

You obviously don't have a service manual or you wouldn't be asking so let me think about what you need to know...

air mixture screws should be set at 1 3/8 turns out from lightly seated. they are not fussy and don't make a huge difference.

before tuning, replace the jets... you can't really clean them if gas sat in them. You would have to hog them out with a wire cleaning tool which tends to change their size. #115 main jets, #17.5 pilot jet and the 5DL31 jet needles should be clipped to 3rd slot. The 76 carbs are not all that fussy if you add pods... just go up two sizes on MAIN jets to #120s. The other stuff will still work fine.

To sync, put the four hoses on the four ports on the carb holders AFTER warming the bike where it holds a smooth idle. You CAN NOT set the idle accurately using the bike tach as they are not very accurate. Should be just below 1500 rpm on most bikes which will translate into about 1100-1200 rpm on a shop tach. Bend the tabs of the mechanical lock washer (it is an hourglass shaped piece of aluminum) off the flat blade screw on the engine side and loosen this screw about 3 turns. Loosen the locknuts on the sync screw just behind it (8mm open box wrench works best). Start the bike... the mercury in your manometer or the vacuum in your vacuum gauge should be between 20 and 25 on whatever scale they use. Tweek the four adjusters so that all four are the same. Blip the throttle and after the idle settles, re-tweek to ensure they are still the same. There is no REFERENCE carb as on your GW assembly. Each of the four carbs is hung from a common throttle slide rod and affects the others when changed. Once you have all four slides the same height, make sure you can adjust the idle speed UP and DOWN. If you can't, then we will have to go over the "BENCH SYNC" proceedure. If you can adjust the idle up and down, then shut the bike off. TIGHTEN the four flat blade screws in front of the adjusters. Take a screwdriver and bend the tab back up and tap it using a small hammer so that the tab will keep the screw from loosening from engine vibration. Hold the sync adjust screws with a screwdriver so they don't turn and then tighten up the locknuts on the sync adjusters. If there is a lot of old paint on the adjusters (paint was used as threadlock), it often makes the nuts hard to tighten without moving the sync screws so some pre-cleaning with a wire brush prior to sync is always a good idea. Don't forget to put the rubber caps back on the vacuum ports on the carb holders... btw: in MOST cases, new carb holders are a REAL GOOD IDEA... they seldom seal well when old even if they appear perfect. ANY sign of a crack and they should definitely go.

Hello Weired George,
Is this the same sync procedure for a 1980 kz750e? Also is the Morgan carbtune a good purchase for syncing these carbs?
Thanks for any info....

P.S. Welcome back to biking...to longhaireddbw,s buddy


1973 Z1 900
1980 KZ 750
1975 CB 360
1994 FXDL 1340

oldbikemike wrote:

....Also is the Morgan carbtune a good purchase for syncing these carbs?...

I have a Morgan. It is awesome. It is also very expensive. I bought mine just before the currency exhange with teh U.K. got out of hand so it was what I consider to be reasonable at the time, for such a precision tool with no mercury. Am I biased? Yes. Just wanted to throw in an endorsement...


By the way, there are a million posts in the forum here on how to make a carb balance tool out of spit and bailing twine (I'm kidding, but close), but you didn't ask about that specifically....

I don't have first hand experience with the Morgan but those that own one always rave about it. Of course, since it is expensive, they would tend to rave about it anyway otherwise their purchase would make their judgement suspect bwhahaha Honestly, BT can tell you more about the Morgan Carbtune. I am a K&L Supply dealer so I use one of their professional shop tool type gauges. I get a decent price. The main benefit with this tool is that is has very precise vacuum restriction which keeps the gauges from bouncing and they give you a zillion adapters and a neat metal case to carry the tool in. I never use the adapters by the way. Retail, this tool will cost quite a bit more than a Morgan Carbtune.

Some of the most accurate are the mercury type stick gauges... these are inexpensive but the mercury is getting harder to find if you need to refill. Anyone with mercury experience knows that this stuff has a mind of its own and looks for dark corners of a shop to hide in. The home made gauges MAY work but most folks fail to use restrictors so I would worry about media bouncing in the tubes as the engine vacuum pulses it plus the media will be higher level and easily sucked into an engine. I would take care using a home made system to avoid these issues.

The sync procedure for an 80 750E is a bit different...

Bench sync on a CV carb helps but isn't critical for setting the idle into the center of the idle screw range since the slide height doesn't control idle as much as the idle butterflies which close. If you bench sync, you can get all four butterflies to open/close at the same time and this makes it far easier to do the sync on the bike. To bench sync, open the butterflies so that the last one to open, is just barely open. The bench sync procedure is different from this point as you adjust carbs as pairs. If the last one to open is #4 carb, use the sync screw between #3 and #4 to even those two butterflies. Now even out the butterflies on #1 and #2. Last use the center adjust to even out 1 and 2 with 3 and 4. There are only three adjusters on most CV carb assemblies and this is the way to bench sync.

To sync, warm the bike and set the idle so it is smooth and below 1500 rpm... perhaps 1300 rpm but since the tach on most KZs is really inaccurate, just do it for a smooth idle. With a manometer hooked up to the vacuum ports on the carbs, adjust the pair of carbs (1 and 2 are a pair AND 3 and 4 are a pair) where there is the greatest difference between the vacuum levels on the gauge. THEN do the 2nd pair the same way. You will likely have to readjust a couple times. Then, use the center adjuster to bring both pairs to the same level. Don't forget to reinstall vacuum plugs on any vacuum port that isn't being used and tighten up the locknuts on adjusters, if they are so equipped. Most newer CV carbs don't use locknut/adjuster but just have spring loaded adjusters where the spring tension keeps the adjuster from moving... My Keihins on my Voyager are this way as well as the Mikunis on my Bandit.

Thanks wiredgeorge! You are right about me not having the book. Thank you for the info. I printed it out so I'll have it when I go back over to his house to work on it this weekend.

I'll see if I can get him to buy the new jets. I agree about cleaning them, you can never get them completely clean and if you do then there probably not the same size as when you started. He will probably want to make it run first then when it don't run perfect then I'll get him to get new jets.

The carb holders do have some fine cracks in them and he has already put individual air filters on each carb but I don't think he changed to a larger main jet.

As far as the bench sync, are you talking about using a drill bit stuffed under the slide and making them all the same? I think I heard someone else talking about that. If this is what you mean then what size of bit should I use?

He thinks that cleaning the carbs is going to make it run like a raped ape but I don't think so sense it sat for SEVEN YEARS!

Thanks again for your help on this and I'll keep checking back to see what you say about the bench sync. Jerry...

The drill bit trick is really not a great idea. The point of the bench sync is to ensure that the idle screw is in the center of its range when the slides are open just a smidge so that the idle screw can both open and close the slides so that idle can be adjusted. While sticking drill bits in will ensure all slides are about the same gap, it doesn't really address the issue of the idle.

On the 76 KZ900 carbs, they have to be bench sync'd prior to installing in this manner:

first, bend back the flat metal washer that provides a mechanical lock for the hex head screw in front of the sync screw.

loosen the hex head screw (with the slot)

loosen the locknut on the sync screw

shut the slides using the idle adjust screw. Then tighten the screw a few turns so that the slides are just opened.

adjust all four slides to the same height by eye using the sync screws.

shut the slides using the idle screw so only an eyelash of opening is visible and readjust using sync screw and then reopen them about 1.5mm

This 1.5mm opening will give you about the correct idle speed; note that you can open and close the slides using the idle knob. If you use a big drill bit, it isn't likely that you will be able to close the slides sufficiently after making the leveling adjustments.

BTW: If you see cracks in the carb holders, GET RID OF THEM... You WILL hole a piston if air leaks through any cracks and you can bet the seal isn't good. DO NOT try and repair them. They ain't that expensive especially compared to a new piston. I KNOW THIS FROM PERSONAL EXPERIENCE... The carb holders are almost tune up items... expendable supplies and should be replaced every few years. Any that have cracked are likely the originals.

Thanks again wiredgeorge!

I'll check out the way they are set and compair it to what you said. You sure have enlightened me on this and everything else that I needed to know. I'll let you know how it comes out. It may be a couple weeks before I'm able to get the parts needed and the time to do it.

Thanks again and always keep the shinny side up!