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Starts choked only, wont stay running, kills if throttled.

28K views 4 replies 5 participants last post by  drdata 
#1 ·
I'm not sure if any of you all remember me, but I'm Nate. I've been a member of HSN since around 2004 or 2005. I was very intereasted in getting the bike going before I left for basic training, but life's been a blur. I am now graduated from my high school, and currently awaiting my 6 months of training at Fort Sam Houston. I'd like to get the bike running correctly before I go...


History of the bike is as follows... The bike was bought in 1995 with about 1 mile on it. The first owner got about that far from the dealership before he lowsided it. My dad bought it in 1996 for very cheap, and had it mostly fixed. It still needs a right side mirror, and there's some scratches on the right side turn signal. The pipes were ruined in the crash, cobra shotguns were put on. Un baffeled GOODNESS. The bike is very loud. The bike ran, and he put about 250 miles on it. The pipes were starting to blue, so he was apparently adjusting the carbs or something, and riding it short distances. He passed away in 1997, and I miss him dearly. It was parked after that. In 2002 it was brought to our house, where I detailed it, changed the oil, and let it sit (covered in my shed). I changed the oil again in 2005, when I bought a battery box for it and replaced the battery (old one rusted tight...)
I also por-15'd the tank. The tank screen was full of varnished fuel, but I cleaned it.

Anyways after I got back (2007) I bought another new battery, and have been trying to get it running since.

It will start if I turn the choke full to 3/4 of the way on, and do not touch the throttle. It will stay running for about 4-9 seconds, and then kill. It will immediatly restart, but the same condition percists. If you dont have the choke on, it wont start. If you have the throttle open, it will not start (with the choke on, or off...)

Right now i've got the seat off, because I replaced the air filter (small amounts of old mouse debris) It will stay running with the choke on, and if I'm letting the gas from a propane torch into the intake. It runs with the same condition if I spray carb cleaner down the carbs, with the tank removed and the line empty...


With it running with full choke, and the propane going, the cylinder closest to the rear is not getting enough fuel to fire. It does have spark. The exhaust from that pipe is lukewarm, and it tries to suck your hand in every other firing. The exhaust from the other pipe is hot, and there is no sucking action.

I've taken the air intake off, and sprayed lots of carb cleaner down that carb with it running, and it appears that some gets to the combustion chamber because it effects the idle (too much kills it, just a little bit brings the rpm's up)

So far I'm at a loss, and suspect a fuel problem, mainly from varnished fuel. I drained the gas tank and filled it with a 50/50 mix of 91 octain (is it supposed to be 87?) and sea foam. I started it, and let it run for a min, then shut it off. I'll start it in the morning and see if it's better in any way.
Any ideas on where to start with fixing the problem? I've got about a week and a half before I leave again (for 6 months)
Any opinions on what I could do?
Thank you for your time

~Nate
 
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#2 ·
If it's been sitting like that, then your only real option is to take the carbs off and clean them out. There's not "quick solution" for this problem. They're gummed up, and the idle and/or pilot jets are plugged up. (Especially if you need propane to get it to run!)

Use the "Jetology" sticky to guide you. Your bike will be a bit different, but it will help you.

Use a digital camera to take pictures of things before you take them apart. This way you'll be able to reference where all the tubes and things went when you're putting it back together.

Do one carb at a time, so you won't swap parts between carbs.

They are complicated, but if you take your time, you can get this job done right in a few evenings.

Good luck, and welcome back!

--Justin
 
#3 ·
I had the same exact problem on my 02 spirit vt1100. It sat for awhile and the fuel tank got gummed up really bad.

I cleaned the tank really good and the carbs. It still did the same thing though, it wouldnt start with the idle on, and if I gave it gas, it was just die.

Then I replaced the fuel filter. Ffollow the gas line to under the bike and you cant miss it. I took that off and the same stuff that was in my tank was caked into the filter. It was like a magic trick and the bikes been running good ever since.
 
#4 ·
Agreed

One of the many problems with Gasoline is its tendency to varnish so severely and so quickly in an unused motor. It is really a very dirty fuel in that regard.

I totally agree with the two posts above. The ONLY way to get this motor running is a full carb rebuild. Keep your carbs together mechanically so you dont have to re-synch them, but work on one at a time so you dont mix up internal parts.

Also, If you are really careful you might get away with doing it without a carb kit and re-use most of your gaskets. I would use a very soft solvent to begin with (ethanol, isopropyl, WD-40, simple green) then move up to the harder stuff (gasoline, carb cleaner, choke cleaner, seafoam, berryman, parts washer solution) to get the really bad parts cleaned.

Areas I would pay really particular attention to:

1. Float bowl movement and float pin movement. Make sure they both move very freely and the pin is not stuck. A stuck float bowl pin is typically the first thing in a varnished carburator to gum up.

2. Needles - both pilot and main. Make sure they and their passages are clean and shiny. If you have to pull the needle jet out and manually clean it with emery cloth or 2000 grit sandpaper, it is worth it to make sure it has a near-mirror finish on it. (if this does prove necessary, simple take a small piece of very high grit sandpaper in one hand and simply twist the pin ever so GENTLY back and forth in a blanket of this sand paper. Wet paper works best for this.)

3. And finally your main jets. Everyone worries the most about their main jets, but they really are the least likely thing to gum up in a carburator. Clean them really well. Many people recommend NOT putting anything through the hole in them (wire brush bristle, small copper wire) but personally I have never had a problem doing this as long as you are really careful (25 years of rebuilding racing carburators on cars and never damaged a jet yet :))

Basically go slow and use common sense. Dont force anything clean. Use soft bristle brushes (nylon, toothbrush, etc) if you use any brushes at all.

A few final thoughts on carburator rebuild:

Location - Personally my favorite place to rebuild a carburator is the kitchen table. I do this for two reasons. #1 it forces me to be especially clean and organized which is really critical when it comes to keeping track of all the parts. and #2 sitting down and watching TV while rebuilding a carburator sets a perfect pace for such a delicate job. Slow and easy is really important. It is actually very much like cleaning a gun "You need to clean every single surface on every single part, but you also have to be absolutely careful at the same time."

And final thought - make really sure you do not mess with the little brass/copper tab on the back edge of the float bowl. This is really soft metal and bends very easily. Even a slight adjustment can make a carburator flood or lean out when it should otherwise work perfectly fine.

Sorry for the rambling, but I hope this helps :)
 
#5 ·
Bike won't start

I primarily comute to work which is a short distance. Then before long the carb starts to get clogged up. The engine starts cutting out when throttling and have to choke to get started and dies when you stop at an intersection. I started adding 2-3 ounces STP Carb Cleaner about every 4-6 fillups. I have not a problem since.
 
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