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idle/carb problems

3275 Views 3 Replies 3 Participants Last post by  r409z

I posted about 2 wks ago about some carb problems i was having with the overflow trying to leak on one side. I tried to fix it...and it worked for a while, but in the meantime i decided to get a used replacement carb...and some new carb boots. (old ones had cracking)

I have torn the carb apart several times...and have checked and rechecked everything. I did a valve adjustement...but i noticed it was difficult to get the feeler guage in the exhaust valves....so I set one of the intake according to the feeler guage...compared the amount of play allowed in it...(moving it up and down) and set the rest of the valves accordingly to it...w/o use of the feeler guage.

I put the new carb boots on....cleaned the carb really well...(all jets are clean) and i put the carb back on. The back intake boots didn't like to get back on the carb...so i kind of left them hanging there....so i don't have an airtight seal on the back boots and carb...but the front ones seem like they were good and tight.

I started up the motorcycle and it ran horribly! Instead of dripping gas from the overflows...i got bad idle...bad throttle response. Motorcycle didn't even want to start....i got a vacuum guage...and was able to sync the carbs pretty close 4Hg @ 4,000 rpms...both carbs were pretty close.

The motorcycle now idles ok...but still some problems. I played with the air screws and noticed they were 5 turns out....the book says they shoudl be around 2 turns out. I set them to 2 turns out...and i've had all kinds of problems.....especially with backfiring....i can feel the carb move like a sudden shock of energy when it occurs.

I did a compresssion test...and at cold the compression was a little off between cylinders...one was 135 other was 152. When i did a compression test at hot....one cylinder was 148...the other was 153. So that should be good!

Also...now that the carb is messed up....i have seen the engine smoking a lot more.....it's an old motorcycle 81 kawasaki 440 ltd, so a little smoke isn't bad...but it's been smoking both black and white smoke. I did notice that white smoke was comming mostly out of the left cylinder pipe.....but only when the motorcycle was leaning against the kick stand....if i put the motorcycle flat...the smoke cleans up substantially.

I don't know where to start with this thing. I did just have carb problems...and i think most all my problems still lie in the carburetor. Anyone have any suggestions?
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go to the FAQ section of the forum....you will find some helpful info on carbs in there. sounds like an air mixture screw though.
generally main jets are from 7K to redline, needles are mid range and air mixture screws are in the range you are having trouble with
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