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Discussion Starter · #1 ·
Hey All, I've been reading here for the past couple of weeks after deciding to ignore my better judgement and make a vintage KZ my first bike. Anyhow, I've just pulled the trigger and bought an '80 KZ750 twin for $700. The carbs seem to be pretty gunked and the tank is a bit rusty, but its only got 13k miles on it (and it runs). Its in the shop at present getting the carbs cleaned and a little tune-up (I'm not really capable just yet), but I'll post pictures when I get it back.

Just wondering: are there any significant safety issues with regard to this bike? In particular, I've heard some nasty things about the starter clutch... What is best practice? Thanks so much, and I look forward talking with you all in the coming months.

-Josh
 

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I've had several 750 twins over the past few years, and I've been active in 750 twin discussions on other forums, and I'm aware of only one case of the starter clutch causing the motor to lock up, and one case where a bolt backed out far enough to make noise as it hit the case.

It's common for the starter clutch to fail to work though, and in that case you use the kick start lever :)

I have two 80 KZ750G twins, and a 79 KZ750B, at the moment.
 

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Discussion Starter · #3 ·
Well, I'm glad to hear someone out there likes these bikes!

Anyhow, my electric starter is broke (the problem seems electrical: absolutely nothing happens when you push the button). But that's definitely not on the priority list to fix. Do you have any suggestions for startup procedures when kickstarting (choke, throttle, technique)? Thanks for the reply.
 

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just to make myself sound stupid . I bought an 80 kz650 2 years ago( my first bike in 25 years) and was having the same problem turns out all I had to do was pull the clutch in and it worked fine , took me 4 months to figure that out and I felt really dumb
 

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Discussion Starter · #8 ·
BS38 carbs

Hey, so I just found a pair of BS38s from a '78 KZ750 on CL. I'm thinking about buying them just to take play around with (or maybe pass along to someone around here who needs 'em). Sounds like they are set up a little differently than the BS38s on the '80 twin, though, so I guess I couldn't swap them in (without some extra work). Anyhow, they're $40. Worthwhile?
 

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The 78 BS38's will swap on your bike with no mods, and carb kits are actually available for the 78, while "not" being available for the 80 BS38's.

Buy them and slap them on your bike.
 

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Discussion Starter · #10 ·

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Does your bike have individual filters and 2 into 1 exhaust? If not then I don't know why you would want to change the jets on the 78 carbs. The only difference between the 78 motor and the 80 motor is the carbs, the 80 carbs were only used on the 80 750G, and the carb kits for the 750B won't work on the 750G.

The following info was posted by wiredgeorge at the site linked below:

The Keyster carb kits work for the 1976-79 BS38. In 1980, Kaw changed the needle jet and jet needle as well as the pilot jet. Since the kits contain the jet needle and pilot jet, they will work fine for the 1980 BS38 if you reuse your old jet needles and use a #40 pilot jet type Mikuni BS30/96. In 1981, they started using BS34 carbs probably because the set is about 90 lbs lighter than the BS38s. Specs:

Type BS38 1976-1979
Main jet 125
Main Air Jet 1.0
Needle Jet Badge # Z-4 or Z-4
Jet Needle 4JN19-4 or 4HL12-3
Pilot Jet 45 or 40
Pilot Screw 11/2 + - 1/2t turns out
Starter Jet 110
Fuel level (from bore center) 31 ± 1 mm
Fuel Level 4.5mm ~ 6.5mm

BS38 1980 KZ750B4 and 1980 KZ750G1 models
Main jet, 125
Needle Jet Badge Y3,
Needle Jet 4HL14
Pilot Jet 40
starter jet 45
Service Fuel and Design Fuel Level the same, pilot screw -blank
main air jet 1.0

Posted on the Kawasaki Twins board.

THE KAWASAKI TWIN OWNERS FORUM :: Index
 

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retro rider
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...wondering: are there any significant safety issues with regard to this bike? In particular, I've heard some nasty things about the starter clutch... What is best practice? -Josh
I think the saftey issue you are refering to is a failure of the starter clutch that will lock up the engine.

The best practice in this case is to pull in the clutch as-fast-as-possible. :shock:

Jokes aside, the best thing to do is pull the starter clutch and check the 3 alen bolts, if they are loose, remove them, apply a thread lock and re-tighten them. If you do not pull the starter clutch you will never know. If you do this check/fix you should have nothing to worry about.

I ride mine most every day

 

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retro rider
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Mines a 79, but not as shiny as your 80 :)
Actually your engine looks much nicer than mine... while my paint looks good in the photo, I am learning hard lessons on using a modern laquer on a commute bike. I have done some bad gas damage to the tank.

Here's my 79. Unrestored not running with 7,000 mile on it.

 

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itching to ride
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They are all fine species that have endured the test of time.
I was wanting more a standard version bike but could not pass up the deal I got. No cash just some trading. But have spent money to get her running. Guesstimate 400-500 duckies.
 
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