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need advice on sputtering engine

6K views 12 replies 6 participants last post by  tereich 
#1 ·
1997 Vulcan 1500 classic. Checked the air filter and crossover for blockages and proper sealing, also checked the spark plugs for corrosion/wetness. the plugs had slight dusting/buildup on them and so I brushed them off and put them back in.

The bike starts fine and idles normally. If I give it throttle while idling, it's fine, makes no strange noises.

Most of the time when I ride its fine, no problems and I can go 100mph for miles with no problem BUT sometimes it starts to sputter/stall around 70mph. If I give it throttle at that point, there is no power and the bike starts to slow down.

After slowing, I can resume riding normally until 65-70mph where it will happen again. When I let go of the throttle, it backfires quite a bit (more than normal).

WHAT IS HAPPENING??!
 
#2 ·
When was the last time the carbs have been drained. You may have some gunk floating around intermittently blocking your jets. I had this happen to me with my Yamaha ATV. I just turned off the fuel and open the drain screw and blasted it with carb and choke cleaner. Then closed it and turned the fuel on and ran fine after that.

May be more involved but we may need to know some more history of the bike.
 
#3 ·
Hey, your idea sounds pretty good, I will look into that. I don;t think its a very serious problem because, as I mentioned, I've put hundreds of miles on the bike and had it up to 100-110mph with no problem for extended rides. It can't be something really serious or I feel like it wouldn't run so well other times
 
#4 ·
Of course I don't know what you're talking about as far as draining the carb ha. The drain screw? Also, I thought it may be getting too much air, thats why I checked the seals around the air covers. One gasket was bad on the crossover side and so I replaced it. The problem went away for a few days but now its back. And when the problem occurs, it will stop if I choke it a little
 
#5 ·
Hope so. I just hope it not something major and you are just seeing some early symptoms.
 
#6 ·
A lot of times when it runs better with the choke it can be too much air caused from a leak but it also can be from not enough fuel and it is bringing your Air/Fuel mixture to a mixture than will burn better.
 
#7 ·
Vn400 1999

I have a problem. open the throttle when cruising and the engine starts to splutter and die. Draining the carb works for a short time but I think they need a thorough clean and an in line filter to stop the crud getting back in.

I have tried for 18 months to get an owners manual and or workshop manual via the Internet, dealers and also Kawasaki but to no avail. Can anyone help me to find these.
 
#8 ·
I have a problem. open the throttle when cruising and the engine starts to splutter and die. Draining the carb works for a short time but I think they need a thorough clean and an in line filter to stop the crud getting back in.

I have tried for 18 months to get an owners manual and or workshop manual via the Internet, dealers and also Kawasaki but to no avail. Can anyone help me to find these.
Are all these symptoms from the same tank of gas? If clearing the carbs fixes it but then it starts up again, it could be debris in the tank or bad gas. Grab a flashlight and see if stuff is floating in the tank!
 
#9 ·
I have a 97 Vulcan 100 Classic as well and mine will do that on occasion but mine is not always at the same speed. Some times it is at in town speed and sometimes on the highway. I can pull the clutch in a gas it a few times over and over for a couple of minutes and then it will be fine. Very Frustrating but fine for the time being. I have had my tank off and cleaned it out. I have not had the carb rebuilt yet but that is my next step. Something I have been having for over a year now.

I found a Clymers manual for mine on EBAY for about $20.00.
 
#10 ·
Have you had the carbs off yet? Some people have reported similar symptoms and have opened it up to find tiny pieces of floating crud in there that intermittently blocks jets.
 
#13 ·
Romans 5:8, I have not had the carbs off yet. I thought that once riding season is done for this year I will send it in and have them rebuilt. My bike has 45,500 miles and I thought it would be good to have them gone through. I am not a carb guy. They scare me a little with all of the little parts. I do allot of things myself but that is not one I have tackled before.

Thanks
 
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