Rigid_EVO Big bang, detonation !

[sportsterdoc]

It looks/sounds like a typical carb back pop from a lean condition.
Although there is no heading for it, check out all the carb related issues on this link:
http://www.nightrider.com/biketech/c...leshooting.htm

[wedge]

Originally Posted by sportsterdoc

It looks/sounds like a typical carb back pop from a lean condition.
Although there is no heading for it, check out all the carb related issues on this link:
http://www.nightrider.com/biketech/c...leshooting.htm

+1, does sound like a lean condition. Could definitely be an air leak. Check your vac line to the petcock if it still has a vac petcock on it, and if not, check any plug on that port of the carb (my plug cracks and falls apart about every 6 months and it makes the bike sound just like this). Also do the usual tests like blowing propane around the intake mainfold with the bike idling. But also the carb could be just dirty, so if no leaks found, then take that carb apart and clean it good.

Since it ran good before, then there is no reason to look at jetting or tuning at all right now.

Still a bad pick-up for the ignition could do this, so you can't rule it out, but like sportsterdoc said it sure does sound like carb farts though.

[sportsterdoc]

I am thinking along the same lines as Wedge: Vacuum leak is the first possibility to check
When the carb was put back into the rubber intake manifold was it first wetted (water, spit or whatever) so that it would slip in well?

[tara]

Originally Posted by sportsterdoc

I am thinking along the same lines as Wedge: Vacuum leak is the first possibility to check
When the carb was put back into the rubber intake manifold was it first wetted (water, spit or whatever) so that it would slip in well?

i always put oil with my finger on the intake seal for the carb to fit well

[sportsterdoc]

OK, so it was lubed when inserted. I prefer water, as it evaporates and leaves the carb snug, but I would not expect oil to be an issue.

Not ruling out your coil concerns, but still looking for lean, while you await a new coil.

I looked again at your video. Wish it were closer to the carb throat and stayed on the carb. Are you getting a squirt out of the accelerator pump? It was 88 that did not have a pump (just a rich needle), correct?...not 87?

[tara]

Originally Posted by sportsterdoc

OK, so it was lubed when inserted. I prefer water, as it evaporates and leaves the carb snug, but I would not expect oil to be an issue.

Not ruling out your coil concerns, but still looking for lean, while you await a new coil.

I looked again at your video. Wish it were closer to the carb throat and stayed on the carb. Are you getting a squirt out of the accelerator pump? It was 88 that did not have a pump (just a rich needle), correct?...not 87?

it is an newer cV carb model with accelrator pump and yes it throw a good amount of gas when you open throttle.
tonight or tomorrow i will chech what s going on under the gas tank and let you know, thanks for your help

[sportsterdoc]

You are welcome, but I have not yet really been of any help.
I should re-read the thread, again, but I am ready to sign off for the evening: I saw the slide lift some, but not know how much throttle was given for the diaphragm to react.
Is the diaphragm in good condition?
I am reaching here, as an unseated diaphragm would hiss from vacuum loss and not lift the slide at all.
Any vacuum lines on your bike? Is there a vacuum port for a vacuum operated petcock and the rubber cap cracked?

[rejeanprimeau]

When you install your intake manifols, make sure the carb spigot is vertical. Don't try to move it after thightening. For lube I use a bit of grease or oil on the rubber. Lot of problem is solve by being carefull to position the spigot right.

[tara]

took apart carb, it was clean as hell, change seals at the intake, reinstall everything, and it is still exactly the same, backfiring through the carb.
BIG BIG DISAPPOINTMENT !!!

[sportsterdoc]

Originally Posted by tara

took apart carb, it was clean as hell, change seals at the intake, reinstall everything, and it is still exactly the same, backfiring through the carb.
BIG BIG DISAPPOINTMENT !!!

Sorry, but before you rule out the carb and go on to electrical, was there a vacuum port on the carb not covered?...and, if you hold WOT for 2 seconds, does the diaphragm fully lift the slide?