View Full Version : Thumper will idle all day long, any throttle and she dies.

05-11-2013, 06:00 PM
Ok. so i have been through the forums the last three weeks, on this site and another trying to get SOMEWHERE with my thumper.

short story: no luck

It will start and idle fine, with any throttle she will try to die, release the throttle and will go back to its happy idle.
if i give just a tiny amount of throttle (and stop before it tries to die) RPM will continue to rise, and once i get RPM high enough i can snap the throttle wide open and it will respond, but will spit fuel out of the carb.

now i know the usual suspect, the boot, however i just got dan's superboot delivered today, and installed with no difference in what it has been doing at all.
i have also put a new plug in, with proper gap.
new plug wire (i am getting consistent spark)
new diaphragm/slide
new intake manifold gasket/o ring
i have cleaned the jets (165 and 45 it has a vance n hines pipe)
i have drilled out the idle air screws plug, and tinkered with that.
i have reset the float (which i will be testing to see if it helps after work tomorrow)
the gas was not premium, but it was fresh gas, so i dont see any issues being cause by separation in the tank.
i have checked the voltage on my TPS, and that is at .6v and aside from one small jump (from 1.4v to 1.6v) it is smooth the rest of the way, and i do have a new tps ordered, should be in next week.
EDIT: i have also tried running with the gas tank lid off with no difference either way.

at this point im just at a loss. any help, any ideas would be much appreciated. im just starting to get discouraged that i might have put this money into it without much posibility of finding the issue...

05-13-2013, 12:59 PM
How did you clean your carb?
I had very similar issue and I did followings.

1. new battery
2. new boot (not super boot, regular das boot)
3. drained the gas tank -> 1/3 can of seafoam in the gas tank -> put half of gas back in
4. seaform directly into intake (just a little bit)
5. seaform on carb's vacuum hold and fuel hose.
6. using compressed air to make sure the holes are not clogged (be careful, and use goggle)
7. visibly check idle jet is not clogged & make sure carb slide's sound is ok (... hard to explain... )
8. put everything back together
9. and it finally worked.

After each step, and I had no luck and similar thing or worse things happened.
At some point the bike won't even start.
But after cleaning the carb (yes, I know you said you cleaned it), mine started, idles, and runs fine now.

While fixing my bike, I searched many forums, and I found one guy saying he cleaned his carb, and he ended up buying a new carb on ebay and it worked fine.

Another posting suggested to make sure your carb's butterfly is not sticky.

05-16-2013, 09:02 PM
When i found out what the issue was, i was kicking myself in the ass all week long.
if you take the main jet out of the carb, underneath it sits a small silver sleeve that should come up into the throat of the carb, it will go in either way you want to put it in, but only one way works. the sleeve has a small offset ring around it, and the longer end should go up into the throat of the carb, while the shorter end is towards the jet.
i had this in the other way around.
all because i had taken the carb apart last fall, before i had learned much about our carbs. and put that in the wrong way. so i had done all of this work for something my dumbass had done, and had forgotten about till i went through the carb again this spring and found that upside down.

its running now, but i still need a timing module for it. i know that those rarely go bad, but it sat for 4 years and some of that time it was outside in winter under a bike cover. i had lost the cover for the module before i let it sit and i can see cracks in the plastic on it, and when it gets hot it just dies and stops givin spark, if i tap it it will keep goin.

but anyway, i cleaned the carb by taking it apart piece by piece and cleaning with spray carb cleaner. inspected each part before putting it back together and ran some of the carb cleaner right into the gas inlet line to clean anything that might be sitting in there.