My Carburetor Story - Kawasaki Motorcycle Forums
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post #1 of 11 (permalink) Old 03-25-2017, 09:18 PM Thread Starter
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My Carburetor Story

85 Kawasaki ZN700 Keihin carbs, 4k miles on the odometer
When the battery died, I let it sit for about a year and like a big dummy I didn't drain the carbs. Finally installed a new battery. I had a leaky fuel valve so I removed the gas tank, dumped it and washed the rust particles out with gasoline and rebuilt the fuel valve. The screen was good and I made sure my fuel filter was clear. I had to use starter fluid to get it started. It ran really ragged on two cylinders. So, I poured a half bottle of Gumout for high mileage engines into about a gallon of gas and I have been starting it and running it for a few minutes and letting it sit for several weeks. It ran better every time I started it. Yesterday is the first day it fired on all four cylinders. It runs good at idle but still is not quite right. It doesn't accelerate well so I'm hoping the cleaner didn't destroy the diaphragms in the carbs. Anyhow, I'll keep you updated so you can decide if you'd like to try Gumout (with PEA) in your gas to clean up carbs. PEA polyetheramine is supposed to be th best fuel injector cleaner. Chevron techron may have been the first to use it. Today I rode it about 3 miles and it didn't bog as bad as it did yesterday so the Gumout appears to be still working for me. Monday, I will get it inspected, tag updated and will ride the heck out of it and see if the bog completely goes away.

By the way, I bought an infrared thermometer from Autozone and I love it! I used it to check the exhaust pipes temperatures and could tell which cylinders were firing and how well they were firing compared to the hottest temp! I highly recommend this tool!

1985 Kawasaki ZN700 Shaft, 4cyl
1989 Yamaha Venture Royale
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post #2 of 11 (permalink) Old 03-27-2017, 07:44 AM
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I heard that putting half a can of seafoam in the gas tank can also clean things out
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post #3 of 11 (permalink) Old 05-06-2017, 09:43 PM Thread Starter
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Update on my ZN700 carburetor story. I thought the Gumout was going to finish the job but no it didn't. It was starting great, idling great and the bogging upon acceleration was getting better. Then, one of the idle circuits plugged again. So, I decided to take the carbs off and clean them. Is there a trick to disconnecting the throttle cables or is it just a huge pita? It seems to be so hard to do that I feel like I must be missing something.

1985 Kawasaki ZN700 Shaft, 4cyl
1989 Yamaha Venture Royale
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post #4 of 11 (permalink) Old 05-13-2017, 09:46 PM Thread Starter
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The latest saga is after spraying carb cleaner and running wire from a welding tip cleaner through all the jets and orifices, I've reassembled the carbs with the exception of those plastic plugs that plug one of the jets that is held in by the o-ring around the plug. The are really hard to stuff back in with the fat o-ring in place. I'm considering threading the hole and use a screw-in plug instead of the plastic plug with o-ring. Has anyone else done this? It seems to me to be a much better idea than the plastic plug. At any rate, I hope to have it running great by Monday.

1985 Kawasaki ZN700 Shaft, 4cyl
1989 Yamaha Venture Royale
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post #5 of 11 (permalink) Old 05-15-2017, 10:40 PM Thread Starter
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Ok, the final saga of this story I hope. I was trying to insert those plastic plugs back in with some o-rings I bought from ACE hardware. They were too fat to allow the plug to be inserted. So, I ordered the proper o-rings from partzilla to the tune of $8.40 apiece. They came today and the plugs popped right back in. easy peasy. Reinstalled the carbs and the bike runs great. The 74hp is back!

The reason I didn't pull the carbs long before is that I wanted to know if the Gumout would do the total job given enough time. Not this time.

1985 Kawasaki ZN700 Shaft, 4cyl
1989 Yamaha Venture Royale

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post #6 of 11 (permalink) Old 05-16-2017, 08:48 AM
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By any chance did you measure the o-rings? I'm wondering if a metric nitrile o-ring kit would have the size or something close. My HF kit doesn't seem to have anything to match the o-ring in the photo at partzilla, but another kit might. maybe.

Also & this is something I've wondered about, what keeps the plugs from loosening & coming out? Thanks.





....

1981 KZ650-CSR. Competition, Sports & Road.
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post #7 of 11 (permalink) Old 05-16-2017, 09:03 AM Thread Starter
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Actually, I have one o-ring left over because I could not get one of the plastic plugs out. I realized that I would destroy it if I put enough force on it to remove it. A previous owner or mechanic may have glued it in or something. I almost did destroy it and they are not available any more. The hole that the plug is inserted into has an enlarged area for the o-ring it appears and the o-ring is what holds the plug in. I'll see if I can measure the o-ring left over and post the info later.

1985 Kawasaki ZN700 Shaft, 4cyl
1989 Yamaha Venture Royale
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post #8 of 11 (permalink) Old 05-16-2017, 10:56 AM
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Thanks. If the old o-rings are in poor shape, the measurements will probably be off. might still be useful, though.
When doing my carburetors, the new HF o-rings didn't really match the old ones as they were deformed.






....

1981 KZ650-CSR. Competition, Sports & Road.
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post #9 of 11 (permalink) Old 05-16-2017, 08:48 PM Thread Starter
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Since I couldn't get one of the plastic plugs out, I have a new genuine Kawasaki $8.40 o-ring left over. I'm not sure exactly how to measure the diameter but I'll try. I probably need a micrometer.

Today I rode the bike about 75 miles to and from a retiree luncheon and it ran super! Tomorrow I plan to ride it about 65 miles each way to North Myrtle Beach to meet some venturerider.org members. It is bike week at Myrtle Beach.

1985 Kawasaki ZN700 Shaft, 4cyl
1989 Yamaha Venture Royale
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post #10 of 11 (permalink) Old 05-17-2017, 08:06 PM Thread Starter
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I rode the ZN700 to and from N. Myrtle Beach today, about 130 miles total and it ran great! Yesterday and today it's getting 50 mpg on the road. When I got back home I checked the exhaust pipes temperature with my infrared thermometer and all 4 pipes about 6" from the engine were all about 260 degrees indicating the cylinders are all doing the same amout of work. So, I'm very pleased with the end result.

1985 Kawasaki ZN700 Shaft, 4cyl
1989 Yamaha Venture Royale
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