Major troubles : V-Twin Forum: Harley Davidson Forums

Dad's Bike · 09-17-2009, 12:41 PM

Took my bike for a ride a few weeks back and it was running fine. Went for a ride the other day and began to get carb backfire when shifting between gears and whenever I got on the throttle. The bike began to run really rough/stalled and now it wont even start at all. Battery is good, plugs are brand new. Could a vacuum leak cause the bike not to start at all? it is a 2000 fxst (88 ci with CV stock carb) with a stage one kit. Seems to me like it may be a fuel issue? as it sat for about a year prior to me owning it. Any ideas?

Mr Cujo · 09-17-2009, 02:45 PM

Bad gas, gummed carbs.. That'd be the first place I looked based on your description of sitting for a year

ViennaHog · 09-17-2009, 10:46 PM

does the carb slide open when you give it gas?

BrianK · 09-18-2009, 01:16 AM

Carb farting usually indicates a lean condition. As Mr. Cujo says, that may mean some bad gas has become varnish and plugged some carb circuits. Idle jets are particularly subject to this (smaller the hole, easier to plug, no? No sexual reference intended!)

When it happens, try choking the carbs. Does it improve? If so, lean condition confirmed! Then you gotta figure out why. If it came on all of a sudden, then yes, some sort of leakage into the intake circuit seems likely. Fix that if so! But more likely, as Mr. Cujo says, you've just turned fresh gas into stale varnish and plugged yer dang fuel system.

I'd start with the easy route and run a can or two of SeaFoam through your next couple tanks of gas, maybe 6 oz/tank. Good chance that'll clear up your problem. Won't do you any harm, in any event, 'specially with a bike's thats sat for a while.

Mr. Cujo, do you agree?

Good luck mate. Let us know how you make out!

2006xl1200 · 09-18-2009, 01:40 AM

Quote:

Originally Posted by Dad's Bike

Took my bike for a ride a few weeks back and it was running fine. Went for a ride the other day and began to get carb backfire when shifting between gears and whenever I got on the throttle. The bike began to run really rough/stalled and now it wont even start at all. Battery is good, plugs are brand new. Could a vacuum leak cause the bike not to start at all? it is a 2000 fxst (88 ci with CV stock carb) with a stage one kit. Seems to me like it may be a fuel issue? as it sat for about a year prior to me owning it. Any ideas?

What octane of fuel are you running or have you not put fuel in from when you got it?

To me it sounds like worng jetting or like eveyone else says the carb is gummed up.

kemo · 09-18-2009, 07:24 AM

Mine started doing much the same on a trip coming back home. I had changed the plugs a couple of weeks before trip. Used autolites 4164. When I got home pulled the autolites and put my H/D pugs back in. Bike is running great again. I see that you have new plugs so change them back to H/D plugs.

Dad's Bike · 09-18-2009, 09:48 AM

I took the carb apart last night. The jet is a 45 and it is clean as a whistle as is the float bowl. I think I figured out the problem, when I first got the bike, even with the ignition off I could turn the throttle and get a stream of gas through the jet into the carb. Now I turn the throttle and there is no gas (and yes the petcock is open). When I took my fuel line off last night I did get a nice steady flow of fuel through the line. Therefore I think the problem is that something is clogged between the fuel line and the jet. Any ideas? is the jet supposed to shoot gas without the bike running? Maybe a seal then?

squale147 · 09-18-2009, 10:08 AM

Quote:

Originally Posted by Dad's Bike

I took the carb apart last night. The jet is a 45 and it is clean as a whistle as is the float bowl. I think I figured out the problem, when I first got the bike, even with the ignition off I could turn the throttle and get a stream of gas through the jet into the carb. Now I turn the throttle and there is no gas (and yes the petcock is open). When I took my fuel line off last night I did get a nice steady flow of fuel through the line. Therefore I think the problem is that something is clogged between the fuel line and the jet. Any ideas? is the jet supposed to shoot gas without the bike running? Maybe a seal then?

sounds like the accelerator pump isnt working...

JRPUPINO · 09-18-2009, 10:12 AM

I believe what you are reffering to is the accelerator pump discharge nozzle, and provided there is fuel in the float bowl and nothing clogged passage wise in the carb then yes when you twist the throttle you should see a stream of gas shoot from the nozzle. It sounds like you are having an issue with your float sticking. Are you able to blow through the fuel inlet on the carb?

Dad's Bike · 09-18-2009, 12:12 PM

actually I tried to blow through the fuel inlet last night and it was nearly impossible. I had the float bowl on and I literally couldn't blow through it to save my life. My float however seems to move well and it is clean as a bell. Does anyone have a diagram of the accelerator pump? I was wondering if I maybe put the accelerator pump diaphram in backwards when I reassembled it? Also, is there a little spring that is supposed to be above the needle (in the choke assembly) other than the large spring? I really can't wait to get my bike running again and I know it's just some stupid little thing that is preventing it from running.

Dad's Bike · 09-18-2009, 09:38 PM

things are looking up

I checked over the entire carb and could find nothing wrong but when I took it off I forgot to shut off the fuel petcock and realized wtf there is no fuel leaking out all over the place. I then removed the petcock and a **** load of crud came out when I pulled out the fuel filter.... I allowed the entire tank to drain and the gas was really stagnant and reddish brown. Then I replaced the petcock and replaced the fuel and vacuum lines with new ones. Just waiting for my battery to charge then I'll give er a go... Also I have fuel now when turning the throttle even when the bike isn't running so I think it's all good. I also had a chance to drill out the vacuum hole to 1/8 inch and put a screamin eagle spring in there too. Should run good now as it has mods and I checked the jets .... they are 190 main and 48 slow. I think I'm off to the races and all becasue of the help I got on this site. Thanks all once again.

maddogg4 · 09-18-2009, 10:22 PM

If it is a CV carb the first thing that is suspect is the fact that it sat for a year. The so called gas we buy is only oxygenated to last so long. 87 octane breaks down in only 12 days, and premium cannot see 60 days without breakdown, depending on the brand and where you buy your gas. I could not tell you how many carbs we are rebuilding and or replacing due to the fuel having alcohol in it. Pull the carb, drop the bowl and check the seat, jets and the bottom of the bowl itself for corrosive buildup and or rust. We have to physically remove the buildup because carb cleaner is not enough. Check the pin in the float for wear also as the constant vibration dog ears the body and then you just have to replace the carb. Keep the fuel fresh and only run 93 octane no matter what the owner's manual says. Good Luck

JRPUPINO · 09-19-2009, 10:46 AM

If your'e up and running great, if you still have your carb apart I would still check your float needle and seat, your float can move good and your needle can still be sticking in the seat. Also most oem petcocks have a vacuum check valve and fuel will not flow unless vacuum is applied to the port.

nightrob · 09-19-2009, 12:33 PM

Next time put some stabil in the tak, run it a little and you wont have problems like this