Won't idle / Hard to Start / Blue Smoke - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 50 (permalink) Old 05-30-2009, 02:03 PM Thread Starter
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Exclamation Won't idle / Hard to Start / Blue Smoke

Alright, this might be a little long, but I just want to make sure not to forget anything...even the stuff that seems irrelevant...

Did an oil change the other day. Switched to Mobil-1 Full Synthetic 10-W40 High Mileage. Bike ran very smooth for a few days.

Yesterday I put about 90 interstate miles on it at around 75-85mph. Got to my destination, ate, and was heading back home. The wind changed direction and picked up a little, so I figured I would break off onto a slower state highway instead of fight the wind on the interstate. I pulled off and the bike died when I pulled up to the stop sign at the end of the ramp. Still had a little less than half a tank of gas according to the fuel gauge. Tried to get it started again, but it was VERY hard to start. I think I had to hold the starter in with full throttle for 4-5 seconds before it slowly sputtered into life, only to die again within a few seconds. Temp gauge showed normal operating temperature (just to the left of the symbol in the middle). Switched to reserve, just in case, and same thing. Hard to start, won't idle. At some point I figure out that if I keep the RPM's up, it stays running. Eventually got the bike into the nearest gas station (across the street) and when I pull up to the pump it dies again. Fill it up, just in case it thinks it's still thirsty. 2 gallons. Won't start, same as before. Get it pulled up into a parking spot under a tree, figuring I would let it cool down. 30 minutes later, same thing. Hard to start and won't stay running unless the RPMs are over 3k. Figuring this is the best I'm going to get, I drive the rest of the 40 miles home. I run through what appears to be about 2 gallons of fuel during this 40 miles - the fuel gauge is back down to where it was when it died originally.

So I park it, and go out for the night after putting about 1/4 can of seafoam in the tank and letting it run a little to distribute through the carbs, etc...

Go outside this morning to start it up and get a massive backfire, followed by tons of blue smoke coming out of the pipes. But, it idles just fine...for a while, then it dies. Then It's hard to start, then it dies...etc, etc, etc... Blue smoke all the while. I know the bike will put out some smoke right when it starts up, and I"m used to seeing that occasionally, but this was something else...constant stream of light blue smoke, and when I hit the throttle it was like a fog machine going off...

So, I'm appealing to the best knowledge base I know of, which is this forum. Any ideas?
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post #2 of 50 (permalink) Old 05-30-2009, 02:18 PM
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How many miles on the engine and what oil were you using before??
It sounds like a fuel problem, but excess fuel is ussually black smoke.
I am thinking that the syn oil has cleaned up the inside of the engine and is causing oil to go past the rings.
There will be more idea from others.

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post #3 of 50 (permalink) Old 05-30-2009, 02:38 PM Thread Starter
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Engine has 18k on it. it's a '97. I was running some generic Pronto-brand 10-w40 previously.

Also, I forgot to mention that on the way home from the gas station (the last 40 miles) the throttle response was very poor. If I hit the throttle I wouldn't get a response for maybe a second, then it would sputter and kick in.
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post #4 of 50 (permalink) Old 05-30-2009, 02:40 PM
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Pull the spark plugs, clean if needed and see if it runs better.

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post #5 of 50 (permalink) Old 05-30-2009, 04:20 PM Thread Starter
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Okay. Pulled the plugs, cleaned them and put them back in. They were fairly dirty, in my not-so expert opinion. Checked the air filters. Looked fine to me. Checked the oil level and it was over the H line. Drained some oil and started her up. Had to adjust the idle control, but I got it idling at around 1200rpm for about 10 minutes without any intervention. The blue smoke had diminished greatly. After the first few minutes it was only belching the smoke when I hit the throttle. It stopped nearly completely before I took it out for a ride.

It started out clunky and sputtery from the line, but once I got going it was fine. Died one time at the first stop sign but ran great for a mile or so and a few stops in between after that but was always a little sputtery off the line. Pull it into the garage and it dies. Then it starts hard but dies after 5-10 seconds even if I'm giving it throttle.

I'm not sure what to do now other than yell at it. Maybe stomp around a bit.

thanks for your suggestions
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post #6 of 50 (permalink) Old 05-30-2009, 07:02 PM
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blue smoke sound like oil is getting in to the cylinder. also the fouled plugs seem to indicate that too. the bad running seems to suggest that there is a compression leak and oil is getting sucked up. see if you can get a hold of a gauge and pull a plug and see if you have compression on both cylinders. wish i could tell you more.

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post #7 of 50 (permalink) Old 05-30-2009, 08:32 PM
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check the floats and see if they are sticking. normally the only way to make the oil level rise is to introduce another fluid I.E. gas. Most of the symptoms point to to much fuel diluting the oil and letting it blow past the rings

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post #8 of 50 (permalink) Old 05-30-2009, 09:29 PM
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In the opening post you mention pouring in a 1/4 can of Seafoam into a half tank of gas. Some of the Seafoam videos on youtube show a lot of smoke with heavy use of Seafoam. Could there be a connection here?


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post #9 of 50 (permalink) Old 06-01-2009, 12:03 PM
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Could there be a problem with the hoses going to the carb? I had a similar problem to this once and the culprit turned out to be a loose hose at the carb (that really wide and short hose). MPGs died, power was sluggish, and I had to keep it revved up to keep the engine running.
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post #10 of 50 (permalink) Old 06-01-2009, 12:33 PM Thread Starter
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Put some fresh gas in her this morning and started her up. Started just fine and idled for about 5 minutes with full choke, no problems. Got on and rode up the block and back. Slow and sputtery off the line again. Turned off the choke, and same.

Will check the carb hoses and floats when I get home. Had the idle screw replaced a week or two ago. Maybe something wasn't tightened back properly and shook loose...

Is there an easy way to check the floats or do I basically have to remove the carbs?
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