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Discussion Starter · #1 ·
I finally got the '78 back from the shop this week. It needed a safety inspection (last one was done in '83). We did the both front and rear brakes, new plug caps on 1 and 4, and rebuilt the rear master cylinder.

I took it to work today - warmed up fine, and ran great on the 30 minute ride.
3 hours later, I leave for lunch, and have some issues getting it to warm up. Needs full choke, and quite a bit of throttle to keep it from stalling. I finally get'r going, and ride for about 20 minutes until I reach my first stop sign. She dies instantly as soon as I gear down into first and pull the clutch in to stop at the sign. I try cranking it to restart, and can't get it to turn over. The only way I can get it to run, is to fiddle with the idle screw (clockwise). And the choke on again. Then once it runs, I turn the screw back down to ~1600 rpms. Anything lower, and it stalls out. This occurs several times at the next few stops.

Which things should I tackle first? I'm fairly green when it comes to these bikes

The bike was a barn find for me. It had been started and ran each year for the last 15, but not run regularly in about 20. I doubt the carbs have ever been clean. Might I have a vacuum leak?
 

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Discussion Starter · #3 ·
Thanks for the response.
Is there a recommended filter for my bike? It's a 78 kz1000, with 30k on the clock. No mods

I'm also getting a bit of backfiring with letting off the throttle in low gears. Could that be a vacuum leak?

Also, which carbs do I have on my bike?

Thanks
 

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GHOSTRIDER
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Your bike had the Mikuni VM-28mm carbs...A pic would determine whether or not they are the "pumper carbs" (accelerator pump)...Some early KZ-1000's had VM-26mm carbs as well...Use a Vernier Caliper to measure the inside diameter of the carb throat (opening facing the head) to determine which carb size you actually have...Here's a link to Z1-Enterprises and the various inline fuel filter options Fuel Filter Slim-line inline clear 1/4" | KL19-1272-1 | www.z1enterprises.com ...Z1 also has the "carb holders" if you suspect a vacuum leak... Carb Holders w/vacuum plug (4) Z1 KZ900/1000 28mm | IMK16065-028-K | www.z1enterprises.com You really need to get a manual, preferably a "Factory Service Manual"...You'll find them on ebay from time to time and until then, a "Clymer" service manual will do...Z1-Enterprises has those as well...Tell'em "Zoro" sent you...;)
 

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Queasy Rider
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What your describing is clogged pilot circuits...If your not running an inline fuel filter, then GET ONE! It does no good to clean the carbs and then hook them up to a tank full of debris thats going to clog them...
Of coarse you'll have to clean those carbs first. You could try running some "Seafoam" carb cleaner mixed into your gas tank. (available at CTC eh.) Personally, I've never had any luck "running Seafoam" but most people swear by it. It works very well at full strength for manually cleaning carbs.
 

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Queasy Rider
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I actually usually use lacquer thinner and avoid getting it on any o-rings. 'not sure if Berryman's is available around here. I'll keep my eye out for it though.
 

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Discussion Starter · #8 ·
Thanks for the info guys.

I Got them off the bike yesterday, and slowly started pulling them apart. I've got the needles/jets soaking in carb cleaner. I'm ordering new gaskets. I already have those carb holders on the bike, but I think I need a new boot on the air side.

What is the best way to clean the carb bodies? Should I remove the entire carb from the rail? Then remove all the bits (choke plunger, internal guts, etc..)? Soak them in pine sol?

Here is a pic after a quick rinse with carb cleaner before pulling the bowls and covers off.

 

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GHOSTRIDER
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Those are non pumper 28's and NO, DO NOT remove the carbs from the rail! A bogus intake air duct is no big deal...A bogus carb holder is a BIG deal..."Carb holders first!"...They MUST be air tight against the head and at the carb clamps as well...Make sure all the passages in the carbs are clean as well as the Pilot Jets and pilot circuits...Make sure you Bench Synchronize the carbs and check your valve clearances! It does literally NO GOOD at all to try and tune your carbs if you have a tight valve or two...You NEED to get a service manual to understand the procedures...
 

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Queasy Rider
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I wouldn't use Pine-sol to clean the carbs. I use lacquer thinner but if fumes are a problem you can use the over priced "Seafoam". Or as Zoro reccomends, Berryman's B-12 Chemtool. (I'm not sure if it is available in Canada) Yes and get a "Service Manual" . If you can't find one on ebay there is a website called manuals.com or something simular. I bought a photo-copied manual from them once. It was pretty decent. Some of the photos are not quite as clear as an original but still worth it if you can't find a decent original.
 

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Discussion Starter · #11 ·
I'm only soaking the covers and bowls in pinesol. It works much better than the carb cleaner I've got. Jets and needles are soaking in carb cleaner.

What should I use to clean the carb bodies? Does laquer thinner harm seals? What should I use to clean the choke plunger? I've got several cans of sea foam handy. I will order a manual when I get a chance.

Where's the best (cheapest) place to order valve shims? And the tool?


Thanks again folks!
 

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Discussion Starter · #12 ·
I'm only soaking the covers and bowls in pinesol. It works much better than the carb cleaner I've got. Jets and needles are soaking in carb cleaner.

What should I use to clean the carb bodies? Does laquer thinner harm seals? What should I use to clean the choke plunger? I've got several cans of sea foam handy. I will order a manual when I get a chance.

Where's the best (cheapest) place to order valve shims? And the tool?


Thanks again folks!
 

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GHOSTRIDER
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Z1-Enterprises...The only time I buy elsewhere is because Z1-E dont have it or cant get it...Jeff Saunders (the owner) is a very personable fellow and is very helpful on the phone...They also have the lowest prices on hard to find Vintage Japanese Motorcycle parts and accessories...Tell'em "Zoro" sent you...;)
 

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Queasy Rider
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Does laquer thinner harm seals?
Where's the best (cheapest) place to order valve shims? And the tool?


Thanks again folks!
I would by only OEM shims for this reason; Blank Page
Find who has the cheapest OEM shims. I'm not much of a gambling man.

I've heard that lacquer thinner can harm some 0-rings and it sounds possible. I avoid getting it on any o-rings to be safe. If you've already got lots of Seafoam then you may as well use that. I just put some in a small closeable container, drop in the jets and let them soak awhile. Then just for added fun, I shake the container in a stirring motion before removing the jets. If you have access to compressed air, it's a good idea to blow them out after they have soaked. TIP: I like to do one carb at a time. It allows me to keep track of where all the little pieces go and if I really get stuck, I can use one of the other carbs as a guide.

P.S. Don't forget to set up your float heights!
 

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Discussion Starter · #16 ·
Thanks again for all the help. After I soaked the jets, seems as though the pilot jets won't clean up very well. I can't see any light when I look from end-to-end. The main jets cleaned up fine. I need some new o-rings, and new gaskets so I figured I might as well just buy some rebuild kits.

Is this the kit that I would need?



But I have no clue how to get the jet needle out. I'm assuming its attached to the throttle bracket, but I'm not certain I know how to get that out of the carb body without sliding the body off the rail.
 

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well if you have the rebuild kit u won't need cleaning the pilot jets - in my case they were clogged as well and I used set of needles (sewing) to be sure they are cleaned properly;

have you broke the carbs apart (the needle should come out from the top) together with the ``piston''. I see your kit has also new jet needles.

I wouldn't remove the carbs from the rail unless necessary. Wish I could get one of those 1000 cc's ...
 

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Discussion Starter · #18 ·
I can't figure out how to get all the top bits out. There a hinge in the throttle bracket that I cat seem to get apart
 

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Discussion Starter · #20 ·
So the carbs have been rebuilt. Floats have been adjusted. New filter put inline from petcock.

I got it all back on the bike, and it fired up right away. Had it idle for 20 minutes or so. Then shut it off. 10 minutes later, fired it back up, no issues. Took it for an hour long rip around my local roads. Bike obviously performed better with the new carb bits. It was great.

Towards the end of the ride, the same issue popped up. After its warm, when it returns back to idle, it dies out. Then I'm having a hard time getting it to run again. I often have to turn the idle adjustment in order to get it fired up, then cut it back, as it races to 4-5k rpms.

Once I limped it home, I tinkered around with it while it was running. I could get it to idle low, but as I pull the throttle, it races again, then won't return back to a normal idle until I tinker with the idle adjustment.

I notice that my throttle cable has some slack in it, and my throttle doesn't snap back completely. There isn't much play in it, but could that be contributing to part of my issues?
 
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