Hey guys new to the harley lifestyle since Oct of 07. I bought my first bike which was a harley and i love it. I upgraded the Pipes to Big Growl Shraight shooters and added samson baffles. Also I increased the air cleaner to the Screaming Eagle Stage 1 Kit, with back plate and k&n air filter and re-routed the breathers. My problem is that at idle the bike runs great. When I give ease the throttle on it runs well. If i am riding on the road and i jump on it the bike with have a small burp and take off. I have the air cleaner off and when this happens gas comes out of the carb. At first i thought not enough back pressure but many guys i know run straight no baffles, no problems. If the jet was to large at stock application before I had a soaked paper filter. So increasing the air flow and the exit speed should take care of that. I have called local harley shops and i get the ole bring it in well take care of you for 70$ an hour run around. I guess my question is that could it be backpressure, To large or small of jet, Or a bad dyafram ? ? Any help would be greatly appreciated.


Thank you for any helpI can get

Chris

 

Hay... a friend of mine is having nearly the same problem.... and guess what, it all started after he put baffles in his drag pipes.. Tried just about everything to solve the problem... even removed the baffles but the bike is still causing problems... Just a note: He had no problems when running just straight drags (at least he says)..

I (we) believe that something happened to the carb when it started caughing so much.... ruptured the diaphram or sucked dirt into the jet...

We finally gave up... bike is going to the shop next week for a complet carb cleaning, adjustment, jet kit etc... even at 70.00 an hour this kid wants a good running bike....

Hope you can get your problem solved before you are tempted to throw in the towel... good luck

OH BTW.....WELCOME TO THE FORUM.... Hope you enjoy the topics and advise from time to time.... Share your knowledge and experiences!!

 

Seen it happen a few ways.......

first possibility - remember the stock setup on the bike is generally very lean, timing set accordingly, restrictive exhaust (lots of back pressure) - you do a typical "Stage 1" and you change most of that but not the timing and depending upon the exhaust setup (is it right for your exact configuration ? Every bike is going to be different !), so timing vs. whether or not the complete charge is making it into the combustion chamber, could just need more tuning and / or could be the ECM

second possibility - stuck float.... If the gas was on and was not running at more than an idle, gas would come out of the air cleaner - I have seen people (I have done it myself - not on my bike.......but) smack the side of the carb with the handle of a screwdriver....I can completely rebuild a carb if needed, so this was mentioned as a TRY AT YOUR OWN RISK type thing, if ya whack it too hard, you will damage something - NOT A GOOD THING

third possibility - the diaphragm (being a CV carb) might be floating (not dropping as quick as it should) - needs to taken apart, rebuilt or repaired / maybe a new diaphragm

forth possibility - the accelerator pump is dorked up and / or just not seated in the little rubber boot

or it could be something I have not mentioned here.......??????????

Good Luck !

 

Given the mods you made your problem is likely nothing more than running too lean. You simply need to rejet and adjust the mixture screw. Your lean mixture is causing the backfire when you roll on the throttle and that backfire is causing the incomming fuel mixture to be spit back out of the carb throat.

Assuming this problem started when you added the Stage 1 upgrades and the bike was running OK prior, you can likely eliminate ignition timing (it's not adjustable anyway), and if the float was stuck the motor wouldn't be running so great at idle.

Rejet first.

 

Thanks guys for all your help and the welcoming knowledge that youve giving me. After doing even more thinking. Im pretty sure its the carb area if not jets. When i changed my pipes there was a screaming eagle gasket in there already. Im making a general guess but i would say comming from the factory that is not the gasket used. If so someone had to of changed the pipes and got the carb set for those ones. When traded in put the stock pipes on with the screamin eagle mufflers. So it makes me belive that my carb is set for a completly differnt set of pipes. I am planning on having the dealership re-jet so when they do and set the idle and such maybe it will cure the problem. It makes me believe that the jet currently in there is to large so that it floods the carb when i give it a quick twist, burns off and catches up with it self. If any of this makes sense please let me know again thanks for all of you help thats been offered so far its helping me get closer

chris

 

Changing the pipes only on your bike, typically does not require that the carb. be rejetted so I wouldn't assume that that was done. It's likely the increased air flow from the SE A/C you added and as a result a lean mixture, that's causing the problem. But, it sounds like you are going to let the dealer figure it out anyway.

 

hey guys i gave in an took it to the dealer to get some work done on it. I found out when they went to put it on the dyno to set the carb they did not have a jet big enough to get enough fuel into the carb. Turns out it was running very lean. They replaced the fuel valvetake care of that problem. Also the intake seals were out so they replaced them as well 150.00 later i got a bike that runs like a raped ape. The sputter that i would get if i got on it quick is gone, as well the gas out the carb, and does not run lean anymore. Thanks for all of your help but this one was a little to weird for me to tackle. Hopefully this may help another member down the road

 

boy i do got to say that cHarley is very helpful to this forum,to the the ones that listin.
anyway just wanted to Thank You cHarley, you are good
[sm=smiley20.gif]

 

First thanks for a great info page. So
i rebuilt my CV carb. I stepped the Jets up 2 sizes. Both main and piolet. I'm having the same problem. Before rebuild be was stock ran good but not great. Sparkplugs were white ashy covered. Before reading forum I was gonna down size my Jets. Because it is spitting out gas through air cleaner.
After reading I guess I'm going to keep up sizing my Jets.......... Do you fellow Harley riders agree....... Thanks in advance ..... Popster

 

check for intake manifold leaks first removal of carb may have caused a leak. very common from them to leak just out of the blue as well