| Author | Message | ||
     00green |
Once again I don't know the history of this bike but this has been an issue since I first got it. Cleaned the carb replaced manifold seals, no farting during cold start and while warming it up like there was. Now it farts while at and below 3k +/- when throttle and speed are steady. It did this prior but rarely, it seems a little worse now. Pulling the choke does eliminate the farting so it would seem that it has to be fuel/air related. The mixture screw was backed out 1/2 turn at a time and is at 3 1/2 now. I re-checked for manifold leaks using propane and then ether and I'm confident there are none. I have a 48 pilot to try, other than that I could shim the needle and go back through the carb to be sure there isn't any trash in a passage. The carb was actually quite clean inside. Anyone have any other suggestions? Any comments? | ||
| 00green |
I should ad that the bike has what looks like stock header, V&H can, a 5" round K&N, a 45 pilot jet, and a 195 main. | ||
| Scm2 |
Put the 48 in it. If it runs good when the choke is pulled out that is due to the air/fuel mixture being richer than when in. the 48 should lear up your issue. I run a 48 pilot and a 195 main and runs good | ||
| Daveswan |
If you have to turn out the mixture screw more than 3 turns then up the pilot. Ditto with Scm2 - I run a 48 and a 195 main. | ||
| Daveswan |
... shouldn't be getting worse if things remain the same so if it's not the intake gaskets then to your point -- maybe "checking those tiny passages". I had something happen suddenly but more dramatic. The bike suddenly wouldn't run unless I pulled the choke. Ran fine on the way to work! Pulled the carb, looked ok inside but I took it all apart and blew out the tiny passages and made sure I felt air at each exit. More attention to the slow speed passages. Out it back together and all is wonderful again! | ||
| 00green |
I'vbe been working out of town these days and only home on the weekends so bike time has been limited. I went through the carb again and found it clean inside, nothing in any of the passages. I did to my surprise find the float at 5.1 using my digital calipers and reset it to 4.25. Changed the pilot jet to a 48. Still running the mixture at 2 1/2 but it really doesn't to be as sensitive to adjustments as i would have thought. Took it for a test ride. A very positive improvement. Only once the the entire ride it farted out the carb. It does seem to pop more out the tail pipe when i chop the throttle while down shifting. I'm considering putting the 45 pilot back in and shimming the needle up as the float may have the problem the whole time. Comments or suggestions? | ||
| Daveswan |
sounds like you're getting close... I would leave the 48 in for now especially since it seems to be better. I'd check that needle and shim it. It's lean within that cruising range. There is some overlap with each of the circuits. The pilot jet took care of idle and some of the transition. When you shim the needle it will take care of the midrange. You may have to adjust the mixture screw again but you may be just back to 2 – 2 1/4 turns out. | ||
| 00green |
Dave, That all makes sense but what about the popping on de-cel? | ||
| Buellistic |
Exhaust system leak ??? | ||
| Daveswan |
In general, backfiring on deceleration (as opposed to acceleration) is generally caused by a lean condition. The mixture leans out enough to where is fails to ignite consistently. That allows some unburned fuel to get into the exhaust pipes. Then, when the engine does fire, the unburned gasses ignite in the exhaust pipe, causing the backfire. So shim the needle and see what happens... I'm thinking you might not have to turn the pilot screw in at least for now leave it at the 2 1/2 you have it. | ||
| 00green |
Sounds good, tuning is on hold again, the tank went to the painters tonight. I hope to have it primed and blocked out by tomorrow eve and then painted mid week. Next weekend I'll start back on the carb. | ||
| Captainkirk |
Just buy the HSR42 Quick kit and be done with it. Best purchase I've made.... | ||
| 00green |
The tank came back, finally (long story). Bumping the pilot to a 48 has taken care of the carb fart. I can only guess the bike was never jetted right after the air cleaner and pipe were installed. Thanks to all for your input. Dave (Message edited by 00green on October 16, 2011) |
