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Rev. Dr.
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33 Posts
Discussion Starter #1
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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Old Truck Junkie
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4,133 Posts
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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Rev. Dr.
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33 Posts
Discussion Starter #3
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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Rev. Dr.
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33 Posts
Discussion Starter #5
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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Premium Member
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812 Posts
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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Premium Member
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508 Posts
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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Linkmeister Supreme
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7,960 Posts
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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Registered
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178 Posts
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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Rev. Dr.
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33 Posts
Discussion Starter #10
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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Premium Member
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4,054 Posts
Oil smoke is pretty easy to distinguish from the rich black unburned fuel smoke. Oil smoke smells like burning oil, and the black fuel smoke smells like fuel. You said you pulled your plugs. What did they look like? Black and wet with fuel, or black and crusty and dry? Tan? Oily? If you are sure you hadn't overfilled your oil and suddenly it was over full, then I believe you are losing gas down into the crank case. This is really bad to leave in there for several reasons. My gut feeling without enough information to go on is that your floats are stuck and possibly have been letting too much gas boil over and into your cyl when the bike was sitting still, causing the oil burning smoke, and a really rich condition when running. But I'm really guessing. Your battery could cause a rich condition because a weak spark will do that, but that doesn't explain the blue smoke and overfilled oil situation. Your petcock should be stopping any fuel from draining from your tank when the engine isn't running, so that's suspicious too. For the time being, I would turn off the petcock when you park the bike until you figure out what else might be going on.

By the way, seafoam in really heavy doses, like pure seafoam straight into your intake will cause white smoke. Hope this helps. Give us more info if you can!
 

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Rev. Dr.
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33 Posts
Discussion Starter #13
Oil smoke is pretty easy to distinguish from the rich black unburned fuel smoke. Oil smoke smells like burning oil, and the black fuel smoke smells like fuel.
Definitely oil smoke.

You said you pulled your plugs. What did they look like? Black and wet with fuel, or black and crusty and dry? Tan? Oily?
Coated black. Looked like oil.

If you are sure you hadn't overfilled your oil and suddenly it was over full, then I believe you are losing gas down into the crank case. This is really bad to leave in there for several reasons.
I'm not really sure that I didn't put too much oil in. I checked it, but I was in a hurry. Don't have a center stand, so I just balance it as well as I can and read the window (yes, I have long arms).

My gut feeling without enough information to go on is that your floats are stuck and possibly have been letting too much gas boil over and into your cyl when the bike was sitting still, causing the oil burning smoke, and a really rich condition when running. But I'm really guessing.
I would guess another oil change is in order, then? Would that be a useful troubleshooting procedure?

Your petcock should be stopping any fuel from draining from your tank when the engine isn't running, so that's suspicious too. For the time being, I would turn off the petcock when you park the bike until you figure out what else might be going on.
Will do, thanks for the tip.

Give us more info if you can!
Stay tuned... :)
 

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Premium Member
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4,054 Posts
I would guess another oil change is in order, then? Would that be a useful troubleshooting procedure?
Yep, I wouldn't run the engine until I changed the oil. You might be able to tell if there's fuel in the oil when you change it. It would definitely thin it out and smell like gasoline. Keep talking... We'll figure this out!
 

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Rev. Dr.
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33 Posts
Discussion Starter #15
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.
What kind of gauge are you talking about? Sorry, I can tear down and build up any manner of computer with my eyes closed and 6 fingers tied behind my back, but this automotive stuff is still a new thing for me...
 

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Rev. Dr.
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33 Posts
Discussion Starter #16
Well, the bike is draining it's oil out in the garage, and guess what? It reeks of gasoline. Tastes like it, too ;)

So I guess this means I have to pull the carbs and check the floats? Man, it would be totally awesome if I knew how to do that... :) I have the Clymer book for it somewhere, and have actually tried to remove the carbs before. I got all the way up to the part where it says "Remove the RH Carb from the right side of the frame" (or maybe it was LH from the left...), but it just wouldn't budge. I tried for a few hours and gave up. Couldn't figure out where it was still connected to anything...Re-assembled the thing and took it to the mechanic...even he said it was a pain in the ass to get them off.

Any suggestions for the newbie?
 

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Rev. Dr.
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33 Posts
Discussion Starter #17
So, I replaced the oil/filter and ran the carbs dry with the petcock 'off'. I guess I'm going to pull the carbs and check the floats when I get home again in a couple hours unless someone has a less painful suggestion :)
 

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Premium Member
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4,054 Posts
Its going to be hard to figure out if the floats are hanging up without going through filling them up again. It could just be a piece of crud stuck in one of the float valves. The float its self floats on the gas in the bowl and when the level gets high enough, it operates a set of float needle valves that are supposed to close off the gas flow when the bowls are full. If some crud gets in there it can block the valve from closing off and the bowl can overfill. Thank God, I have never had to pull my carbs, so someone else will have to tell you the procedure. Usually we tell who ever to tap on the side of the bowl with the rubber end of a screwdriver to try to un-hang the float, but in your case you may have to remove the carbs. It is interesting that your bike ran fine on the way and then parked for a while then ran like this on the way back. Did you fill up with gas before heading back?
 

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Registered
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96 Posts
My Self, ... Thinking I might would do a compression check before pulling the carbs....start with the simple things first ( of course if you dont have compression on one or both cylinders ... its not so easy ... rebuild more than likely)... if good compression then next the petcock and then the carbs ... just my opionion.:smiley_th
 

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Rev. Dr.
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33 Posts
Discussion Starter #20
Usually we tell who ever to tap on the side of the bowl with the rubber end of a screwdriver to try to un-hang the float, but in your case you may have to remove the carbs.
Bang on something? Now that's my kind of repair! :)

It is interesting that your bike ran fine on the way and then parked for a while then ran like this on the way back. Did you fill up with gas before heading back?
I filled up about 30 miles away from my destination and the bike started acting up about 50 miles into the return trip.

Thanks for the info on the carbs. I'll try the banging trick just on the outside chance it might work.
 
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