Carb Question

[Chaharly]

Ok guys so this time i've actually got a few questions.

 

The first one is. If you have a stuck slide (lets say its not out so its closed) the bike should be able to idle fine? I've been told that these bikes have an idle circuit and a throttle circuit. I do have a terrible memory though so i could be wrong.

 

My problem is my bike isnt firing on the back left cylinder at idle. I dont know how to tell if its running under throttle though. The bike seems to have alot of power. so how do i tell if its running under throttle?

 

I know i have good spark because if i spray WD-40 into the port the idle perks up quite a bit. Tried adusting the pilot screw but i dont think that did anything. And the carbs are freshly synced. Carbs are recently cleaned so I'm not UNWILLING to take them off just UNWANTING

 

So where do I go from here.

 

Any help will be really really appreciated!!! If you're within like 500 miles I'll even come and buy you lunch!!!!

[cowpuc]

Hi Cha, the easiest way to see if its firing on four is spit checking it,, like checking a hot iron - after the bike has been sitting running for a couple minutes, lick your finger and touch the header pipes one at a time, the runners will sizzle - the dead will be cold.. Best way I know of for finding a stuck slide is to look thru the air box and watch em but - I have no idea if that is possible with a Gen 2?

If the slide is stuck in the closed position,, hmmm,, I am not so sure it would idle.. The reason I say that is that is cause of these being CV carbs.. Unlike non cv's - the slide is seperate from the throttle plate that is hooked to the throttle cable and the slides probably find their idle position strickly from vacuum.. My guess would be,, if you spit test and find you have a dead cylinder and that jug is the one that has a stuck slide - you found your issue...

[Chaharly]

Youre right puc You can see the slides without the air box on. Im going to work on it tonight. Starting by trying to clean and blow out that pilot jet.

 

Ive been doing the feel test as you've described. I think I could get away with murder cuz I don't think I've got much for prints left .

 

I'll start with the pilot jet and if still nothing off with the air box we go. Doing research on this site is helping me aLOT!!! When you really think about it there is only really so much that can cause a lack of idle. Either pilot jet, diaphragm slides, no fuel getting to that carb, no spark or low compression. So I'm gonna work my way through it slowly. I don't think I missed anything. I'll keep You updated

 

Thanks again and shoot now I guess I owe You lunch LOL

[BlueSky]

When I bought my 85 ZN700 Kawasaki 5 years ago, it only had 1K miles on it. The owner passed and his 55 yr old nephew tried to get it running right and ride it. He cleaned the carbs and it still ran ragged so he sold it to me. It was running ragged on 3 cylinders. I checked the spark by putting a conductor in the plug wire cap and touching it to the block. All 4 had spark. I put a bottle of Valvoline Complete Fuel System Cleaner in the tank and ran it through. Afterwards it ran smooth on 3 cylinders. I finally swapped 2 spark plugs and the dead cylinder moved with the #2 plug. It was a dead spark plug, something I've never heard of before. Runs strong now!!

 

So, don't rule out a dead spark plug. It fooled me for a good while.

[BlueSky]

If you have a vacuum leak on that cylinder, it may be running too lean to fire.

[Chaharly]

When I bought my 85 ZN700 Kawasaki 5 years ago, it only had 1K miles on it. The owner passed and his 55 yr old nephew tried to get it running right and ride it. He cleaned the carbs and it still ran ragged so he sold it to me. It was running ragged on 3 cylinders. I checked the spark by putting a conductor in the plug wire cap and touching it to the block. All 4 had spark. I put a bottle of Valvoline Complete Fuel System Cleaner in the tank and ran it through. Afterwards it ran smooth on 3 cylinders. I finally swapped 2 spark plugs and the dead cylinder moved with the #2 plug. It was a dead spark plug, something I've never heard of before. Runs strong now!!

 

So, don't rule out a dead spark plug. It fooled me for a good while.

 

Thinking it could be spark related too but when I sprayed wd 40 in the port it started firing immediately on that cylinder. I'll swap the plugs around tonight and see what happens.

[Chaharly]

If you have a vacuum leak on that cylinder, it may be running too lean to fire.

Per your suggestion step number one will be to put the carb tune on it to find any leaks Thanks!

[Yammer Dan]

These things are hard on plugs. Trying a new one might be a cure.

[turtle]

Instead of spit test use a wet rag i too like my finger prints or even an ice cube.

[Prairiehammer]

Instead of spit test use a wet rag i too like my finger prints or even an ice cube.

 

Another trick I use to determine exhaust pipe temp is to touch the exhaust pipe with a crayon. One can even determine relative differences in temperature. The crayon may melt instantly and even smoke a bit if touched to a good cylinder pipe and may melt slightly slower on a not so good cylinder. The key is to touch each exhaust pipe in the same position relative to the head.

[BlueSky]

Or if you have about $20, Radio Shack sells an infrared temperature sensor. Just focus it on the part and it will tell you what the temp is.

[BlueSky]

If the diaphragm on the slider has a hole, that would cause a vacuum leak? correct?

[Seaking]

I had a situation like that a while ago on a road trip where as on the highway on with throttle applied, the cylinder would fire but not at idle.. A short visit to the nearest Yamaha dealer sorted it out real quick.. The tech said he couldn't take the bike in for a week, they were so busy but offered to do a quick check of draining the float bowl.. and wow, that did the trick.. If I remember correctly, he said that this won't work every time but in my case, there was something in the bowl sucking up into the idle circuit and blocking it. I'm not familiar enough with the carbs to know exactly what he meant at the time, but suffice to say it did the trick for my bike..

 

The symptoms I experienced for that problem was that when ever I came off throttle on the highway it would backfire horribly and loud.. (scatters the tailgating cagers real quick) The next morning when warming up the bike to continue the trip and find a repair shop is when I noticed the exhausts fumes not looking right.. and found the left rear cylindre was cold.. but it would warm up as I throttled up the bike..

[Chaharly]

Another trick I use to determine exhaust pipe temp is to touch the exhaust pipe with a crayon. One can even determine relative differences in temperature. The crayon may melt instantly and even smoke a bit if touched to a good cylinder pipe and may melt slightly slower on a not so good cylinder. The key is to touch each exhaust pipe in the same position relative to the head.

 

Really liking this idea! Will do that from now on!

[Chaharly]

Ok guys here was the solution. I'm feeling kind of dumb for doing this actually. Basically what the problem was my pilot jet settings. There were two actually that were turned out an est. 5 turns and one on another cylinder was running way too rich and didnt make any adjustment until I totally closed the jet. AFter letting it run dry for a minute i turned the jet out 3 turns and it runs.

 

Pulled the airboxes off to reroute a few lines and while I had it off I checked the slides. All are operating smoothly and equally, even with the bike cold. Double checked the carb sync and after that It runs like a dream

 

I'm going to try to post a video.

 

Now That I'm done fiddling with it its time to get fresh clean plugs!

 

Edited January 27, 2015 by Chaharly
Clarification.

[BlueSky]

Congratulations! A fix that doesn't cost a lot is a great thing!