Idles fine, bogs and dies with more than 1/4 idle.

[Corp_T]

Ok, long story short. Bike ran fine 2 weeks ago, rode it around and parked it. Went to start it Monday and if I give it more than 1/4 throttle it almost sounds like it's firing at the wrong time occasionally with a metallic thunk type noise and bogs down and dies almost immediately. Start right back up and idles perfectly. I have noticed there doesn't appear to be the standard high rev warm-up lately but on the other hand it's been sitting in 70-80deg weather.

I've checked the boot, gas, replaced the spark plug, pulled the carb and checked the diaphragm, and given the carb a good once over, tried starting and running with the gas cap off.

I'm completely stumped at this point, any ideas?

 

[stamen]

Guessing this isn't a lightning since you said carb? But my 06 Ss has a similar problem.

 

[Corp_T]

2005 Buell Blast, fully stock. I was wondering just after I posted this, could this be a faulty TPS?

 

[pierce]

I would replace the boot anyways.

Disable clutch safety by flipping center diode and cut and twist/solder wires together that connect with the kickstand safety. They fail often and cause misery.

Do those three things and then report back. A boot tear is often very difficult to detect. They should be replaced often until you have Dans superboot.

 

[Corp_T]

Would the kickstand safety and/or the clutch safety affect it even when not moving? Also, anyone have suggestions for best places to buy Blast parts other than eBay?

 

[Corp_T]

Just ordered the superboot from Dan, anyone else that reads this he has a few more for sale right now on eBay.

 

[pierce]

Yes, they can keep you from starting the bike if they are not working correctly.

 

[Corp_T]

The bike starts fine so I doubt it's that. But, I never thought about it though but I'll probably disable the clutch switch anyways, it's a hassle to hold the clutch while trying to start it when I'm holding everything.

 

[Corp_T]

*Ignore*

 

[Corp_T]

oh the good times....I tore half the bike apart and disabled the TPS to test if it was messing up, nothing. Hooked up a timing light and noticed the light wasn't flashing regularly so I figured must be the coil pack or ignition module. Moved the coil wire out of the way and everything started working perfectly...Bike's been down for over a week because of the spark plug cable.

On the positive side the bike runs great now and the clutch sensor is disabled to let me start it one handed.

 

[pierce]

If it was the ignition you the bike would start to shut down when hot generally.

 

[FIREFIGHT100]

fuel line or fuel filter

 

[pierce]

Blast doesn't have an external fuel filter, but you can try running with the fuel cap cracked open to rule out a clogged vent line. Generally the fuel line itself won't clog, but its common for the vent line to clog and not allow gas to flow freely.

 

[Corp_T]

so, I apparently spoke too soon. I was able to ride it around the neighborhood when I declared it the wire but I replaced it and still nothing. My super boot also came in and I replaced that with no effect. It'll start and idle, but when I give it gas it almost seems to misfire, backfire a little, and almost seem like it's locking up before dying.

At this point I think I'm just going to keep working my way back but I have no earthly idea how to isolate this anymore.

 

[kmp00k]

I am going through he same issue right now new plug the super boot, and it starts but not the normal high idle, then given throttle it dies right out.

 

[ezblast]

Check your tank vent and hose - try riding with gas cap off for a bit - if no problem then the vent and hose are suspect.
EZ

 

[Corp_T]

Ezblast, thanks for the suggestion, I tried with the cap off and it still had the same problem. Also, I was completely unable to ride, any sort of throttle or load caused it to sputter and die.

Short story, runs now.

Long story, I tore half the bike apart, poured out everything I could from the carb hoping maybe there was just some water in it, I also disconnected the TPS and auto-enriching circuit just in case and started her up. Gave the same problems so I tried revving it a bit, sputtered and such as it had been there was a nice pop and it runs fine now. I'm hoping it was just something ridiculous clogging something.

I'm going to run some carb/injector cleaner through the gas and probably next weekend plug the TPS and choke back in and make sure it keeps running just to be sure.

 

[prototech]

FWIW, my brothers blast suffered the same symptoms. We after much chasing found the fuel (ethanol mix) separated in the tank, at first we thought it was water from a leaking cap/gasket, but after replacing both and it recurred. on a lark we lit the "water" on fire and it burned! He started using 100% gasoline and had no problems except when using "gasohol". leaving a partial tank in the bike always led to problems within a few weeks requiring a tank drain when the level of alcohol reached the bottom of the main pickup diluting the fuel to the carb. the only thing we figured is the vent is stuck open and drawing in enough moisture to cause the alcohol to come out of suspension. we live in East TN with miserable high humidity, and we attribute it to this, that's our best explanation after a year of playing with it. i hope it is of some help to someone. He has stopped riding it and we haven't replaced the vent. but a full tank pretty much stopped the issue.