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Discussion Starter #1
Was riding to work and the engine started acting up. Thought I may have been out of gas, but when I switched to my aux tank, the same thing. I was able to ride 10 miles to home, but sputtering and popping all the way. Did notice the front of the engine was oily and dirty, but until this happened I had no troubles with it. Idles fine. When I rev it up the sputtering starts. I changed plugs and tightened battery post. No help. It's a 2002 with 35K miles. Any thoughts. (please don't say get a new bike)
 

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Was riding to work and the engine started acting up. Thought I may have been out of gas, but when I switched to my aux tank, the same thing. I was able to ride 10 miles to home, but sputtering and popping all the way. Did notice the front of the engine was oily and dirty, but until this happened I had no troubles with it. Idles fine. When I rev it up the sputtering starts. I changed plugs and tightened battery post. No help. It's a 2002 with 35K miles. Any thoughts. (please don't say get a new bike)
I doubt you need to get a new bike...

Did this start all-of-a-sudden? That's what it sounds like from your description. Was the front of the engine dirty/oily before, or is that new?

I have two thoughts to check:

1) The "all of a sudden" factor makes me suspect your fuel system, and particularly the filter perhaps? Maybe some crud from the tank got in there and/or one of the lines, and is starving the engine for fuel?

2) OTOH, the front of engine oily/dirty - if that's a new development too - makes me suspect your front exhaust valve/cover. To me, #1 reason for oily/dirty front of engine developing quickly would be that cover leaking/getting loose... Though I'm not sure a loose valve cover alone would cause the sputtering unless you'd also got the valve clearances outta whack and/or crud got in there...?

Just my 2c...
 

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When is the last time the carbs were cleaned on the bike? A number of things could cause this issue but I doubt replacing the bike will be needed :) Something is restricting fuel by the sounds of it, or your air or fuel filter is disgusting and completely clogged. You'll need to check the filters, check the plugs for signs of running too rich or lean, and then start running through the fuel system. Does it idle smoothly or is it sputtering constantly even when idle and in neutral? Might also want to run some seafoam fuel treatment. Also, is the oily front new and all of a sudden or was it already all dirty? You can have road grime on the front, but there should be oil all over it.

As CJ says, the "All of a sudden" aspect is suspect, need more details on the oil on the front aspect.

Good luck!
Dan
 

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Discussion Starter #4
yes, the sputter started all of a sudden 10 miles into my 12 mile ride to work. I had notice a small oil leak a while ago, but i could never tell from where. The oil would collect on the frame and a couple of drops would fall off the frame after a ride.
The fuel filter sounds like an easy and inexpensive first step, and I'll take a look at that. But the strange thing is it seems to idle fine. Thanks again!
 

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When I'm troubleshooting my bike, I always take the "cheapest/easiest fix first" approach... i.e. start with the fuel filter before you start ripping the works apart.

Having said that, I'll ditto the recommendation to run a seafoam-spiked tank through her.

KC
 

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yes, the sputter started all of a sudden 10 miles into my 12 mile ride to work. I had notice a small oil leak a while ago, but i could never tell from where. The oil would collect on the frame and a couple of drops would fall off the frame after a ride.
The fuel filter sounds like an easy and inexpensive first step, and I'll take a look at that. But the strange thing is it seems to idle fine. Thanks again!
Well the bike requires much less fuel and air when idling, so it's a restriction problem. You should definitely figure out where that oil leak is coming from and as you said, start with the fuel and air filters and go from there and run the seafoam. As Casey says, start with the cheap easy stuff and go from there...

By the way, for anyone else suffering from this problem and recent cleaned and recharged their K&N filter, severely oversaturating the filter with the oil can cause these same symptoms.
 

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Well the bike requires much less fuel and air when idling, so it's a restriction problem..
Not necessarily. The idle circuit and needle circuits on Mikuni carbs are separate. It could easily be a popped needle or other internal carb issue. I'm not sure what V Star we are even talking about here...so its hard to be very exact with any recommendations.
 

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Check inside condition of the tank. Flush old gas out.
Change the fuel filter. Try again. See if anything has improved.

If no change you will need to pull the bowls off the carbs.
Cleaning of the main and pilot jets is fairly easy to do and reassemble.
You only have to remove the gas tank to gain access.

I feel the fuel system is where the problem lies.


Mine had very similar issues and this fixed the popping and sputtering issue.
 

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While I agree with the previous posters as far as the dirty fuel system, one thing hasn't been mentioned. When did you last refuel? Is it possible you simply got some bad gas? Maybe it has water in it? I know that's rare these days but it does still happen.
 

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Not necessarily. The idle circuit and needle circuits on Mikuni carbs are separate. It could easily be a popped needle or other internal carb issue. I'm not sure what V Star we are even talking about here...so its hard to be very exact with any recommendations.
Good point, you're correct.
 

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Sounds similar to a problem I had on my bike. I thought maybe it was bad gas at first. Ended up being the carb needle set and the throttle valve that needed replacing. The carb needle broke and 2 of the plastic retainers in the throttle valve also broke. Might be worth checking to see if you have a similar issue.
 

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Excuse me but why does everyone blame it on fuel?
I thought by now most owners realize that the 02s and other models like to foul spark plugs, I always had a spare plug just in case.
Try new plugs first.
 

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Because popping and backfiring means the plugs are working fine.

Fuel delivery causes these issues. Fluctuations between lean and the correct mixture are what makes the popping, bucking, and misfiring.

My bike did exactly to the letter what the OP said was going on.

Fixed all of it with only carb related repair. Same plugs I have now
were in the heads then. Raped ape running now w/ narry a miss.
 

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It's usually a lean condition at idle that causes backfire through the exhaust....

After that it is vacuum leaks......

then ignition.....
 

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Discussion Starter #18
Thanks to everybody who responded. I drained the tank and removed it. That's when I heard a metallic rattling on the inside. Turns out there were 3 springs, a screw and a ball bearing in there. Maybe the gas cap fell apart on the previous owner. Anyway, with the help of a magnetic screwdriver, I'm back on the road!
 

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Thats great to hear.... Just know that because the main fuel supply comes from a tube in the petcock that reaches into the fuel level.
Hence- This is what makes the level go from main supply to reserve supply.

The reserve pulls fuel all the way from the lowest portion of the tank
at the bottom of the petcock assembly.

So any parts that would be rolling around in the bottom of the tank and possibly get stuck around the petcock would only hinder fuel flow when the Reserve position is used...
 
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