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Discussion Starter #1
Can anybody help me with a problem I'm having. My 1999 750 has developed a REALLY TERRIBLE sputtering and hesistation problem. It wont stay running at stops and at low RPM's it sputters like crazy. I was using 85 Octane all summer and have a feeling that the MTBE they use in Colorado gasoline during wintertime might be a cause. I replace the stock Champion plugs with NGK's and about 2 weeks later---BAM, hell broke loose. I've cleaned them many times and a spark test shows plenty of fire. I've tried bumping up fuel grade, but to no avail. I've drained the tank completely. Went back to go back to 85 octane. Ran great for 2 days!!!! Then I filled up with the premium, and the bull&^%$ happened again.

Need some help--Also what is recommended for winterizing the Ducks???

Thanks,
Marcus
 

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First, stop using premium. It's not the answer to your problem and it's causing other problems. Put 87 octane in it, give your plugs a good cleaning and keep using 87.

I'm assuming you have stock compression in the engine. Hi comp mods would justify higher octane.

Second, I'll bet your rough running problem is carb icing. I had my first icing of the season last night. I find that when it's in the 40s, my bike starts and idles just fine. But after I've ridden at any kind of speed for ten minutes or so, I experience the symptoms you describe: popping, sputtering, roug running and refusal to idle. It sucks! I'm afraid that I've found no solution.

There are apparently two carb heater kits which may or may not be available. One ran current through the float bowls to generate some heat. The other diverted the engine oil from the oil cooler (which you don't need or even want when it's colt) through the carbs. Sounds messy to me!

I'm told the other solution is Keinin FCR Flatslides: the slides rattle around preventing any ice buildup. They reportedly DON'T ice.

I'm a little surprised to hear a report of icing in Denver. I would have expected your humidity to be substantially lower than ours here which should minimize the occurance.

Of course it could be something else entirely, but it sounds too much like my bike to be coincidence!
 

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the electric heaters do almost nothing. if you go for a carb heat kit go for oil. is it really in the low 40's in Denver?

try draining your carb bowls to see if there is any water. i doubt the winter fuel is your problem unless this is your bike's first year in Denver. in that case, i would look for a lean condition.
 

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Hi
If it is an icing problem, there is one thing I have done on cars that helps and that is to remove the crank breathing that goes into the air filter.
One way to check if its ice, run the bike untill it starts to misbehave then stop the engine for a couple of minutes alllowing the carbs to warm up. Then start it up again and if your bike is running good now (for a while ) there is a big possibility that ice is your problem.

DVC Keld
 

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what about while the bike is being stored for the winter? should the gas and oil be drained?-- yes this is actually a serious question :p
 

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If you're experienced carb icing, it should go away after five minutes of being stopped. Even with the engine off, the heat should melt any ice, but with the engine running (blipping the throttle, or whatever), it should go away fairly quickly. My bike has never taken more than about two minutes to return to normal. I just have to remember when riding in the winter that the first time I come to a stop after riding a few miles the engine is likely to die unless I work the throttle a bit.

As for preparing for winter storage, there is an excellent FAQ on this site (it was the very first one) explaining more than you ever wanted to know on the subject. Check it out.
 
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Discussion Starter #7
I have since ruled out the carb "icing" problem. I have ridden on cold night here in the rockies and have had no problems. Then other times when the weather is warm, the bike starts doing that sputtering and hesistation thing again. So, I gotta beleive that icing cant be a problem. besides, I have dribbled a little "Heet" into the fuel to absorb any water in the fuel. So, no water=No ice, right???!!!

But, Now I have a new question--Has anyone ever had a problem with AIR in the fuel system. The transparent green fuel lines on my '99 750 has shown a bit of free space in them. so, I'm thinking maybe I'm having a fuel delivery problem. Can anyone shed any light on this???


Thanks,
Marcus
 

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Rainman - carb icing is from moisture in the air and tends to happen at about 40 degees F. when it gets real cold, there is not enough moisture to freeze. don't put any more stuff in your fuel. you might be right on fuel delivery. are the bubbles before or after the fuel pump? can you describe the symptoms a little more? oxygenated fuel will affect your bike, but not that badly.

tonyj - fill with fuel using stabil according to instructions, run bike, change oil and filter, leave oil in, fog cylinders. or do what i do. ride and freeze.
 

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I've had similar problems with my wife's M750 but never with my S4. Fouled plugs, running on one cylinder, one failed plug. Don't know what the solution is though so if you find out share the knowledge. I'm also in Denver and it's not icing, happens in the summer too. Ihave found that NOT using the choke helps.
 
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Discussion Starter #10
This goes along with my first post-I was curious to know the symtoms of a "lean" condition.

Yesterday-in order to solve my sputtering problem, I shot some carb+choke cleaner through the carbs while it was running. Every now and then it would shoot a flame about 4-5 inches long out of the Two Brothers pipes. When I shut it down I looked inside one of the pipes and about a quarter of the packing was glowing red. Funny thing is, since I've done that The Duck has been running well. No sputtering at all.

I didn't think carbs could get that dirty since the gas I put in it never has the chance to get bad or gummy. I always burn it off too quick.

So-I just need to know the characteristics of a lean running bike.

Thanks,
marcus
 
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Discussion Starter #11
Re: Winterizing -wood or tar?

The only time my bike, ( also 99 750) ran like that was on early Spring Sunday mornings went Iit was "dewey" out, 35-45 F, and the ride was only about 5 miles of city driving.

I found if I took a longer route that started with a few miles of 50mph+ it helped. Also this may sound stupid, but make sure your spark plugs are in tight. I was a victim of a cruel joke once...

Ok I read the FAQs but still have a questions about storage. I used to always park my bike on the piece of press board to keep it off the cement garage floor. This year I'm parked in my friends garage, and her floor is basically an extension of the tarred driveway. Do I still need to get a piece of wood under the tires?

tanks,
odd
 
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