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Message started by Bryner on 03/10/06 at 14:26:15

Title: Blue flames in exhaust
Post by Bryner on 03/10/06 at 14:26:15

Hi friends...

I put a Sportster muffler on my '00 last week, I have 1/2 spacer and drill holes in filter housing.
I'm waiting for a new main jet... I have a 125 and I'm going to change it for a 130.

But I have a problem. When the bike is hot and I reduce gears, appears blue flames at the end of the muffler.

What can I do to solve this problem??

Title: Re: Blue flames in exhaust
Post by sluggo on 03/10/06 at 14:45:39

i've had "blue flames" but they've never been related to the motorcycle. ;D

Title: Re: Blue flames in exhaust
Post by Steve530 on 03/10/06 at 23:24:49

Try backing the idle mixture screw out.

Title: Re: Blue flames in exhaust
Post by Bryner on 03/11/06 at 08:32:11

I foud this reading some posts about de mixture screw:

"To do the mixture screw you just drill through the cap over the screw, thread a sheetmetal screw into the hole, and pull the plug. Be very careful while drilling. Use light pressure and stop frequently. It is very easy to drill through the plug and hit the mixture screw."

I use the Babelfish to translate this to Spanish but the translation is very bad and I don't understand it very well... can somebody explain it to me?

Do you think this can solve my problem with the flames?
Somebody had the same problem?

Thanks for all...

Title: Re: Blue flames in exhaust
Post by Steve530 on 03/11/06 at 08:47:10

Bryner. We call that backfiring.

I'm not sure about the regulations in your country, but in the US the Savage carburetor was set to run very lean (use as little gas as possible at idle). When you go from high throttle to idle, the gas and air that goes to the cylinder does not have enough gas to burn. This unburned gas collects in the muffler and eventually ignites, causeing the flame and a loud pop.

You can adjust the idle mixture using a screw on the right side of the carburetor. This screw is under a brass plug toward the front of the carburetor. To access the screw, you must remove the plug. You need to drill a small hole in the plug and thread a self-tapping metal screw into the hole you drill. Then you can grab the screw in the plug with pliers and pull the plug out.

You must drill very slowly and use just a little pressure on the drill so that when the drill is through the plug it will not go further and damage the idle mixture screw behind the plug.

When the plug is removed, you will see the slotted head of the idle mixture screw. Turn that screw counter clockwise to make the idle mixture richer.

I hope this helps. Let me know if you still have trouble understanding.

Title: Re: Blue flames in exhaust
Post by Bryner on 03/13/06 at 04:43:45

I make the idle mixture screw, but backfire continues... :-/

I have 1/2 spacer and the mixture screw 2 and 1/2 turns out. The carburetor was preset 1 3/4 turns out and I turn 3/4 more... or I have to count from the 1 3/4 that was preset? (1 3/4 + 2 1/2 = 4 1/4)

I hope you understand the last one ::)

I will not have new main jet till thursday. I'm using stock main jet (125)...

Thank for all.

Title: Re: Blue flames in exhaust
Post by lancer on 03/13/06 at 06:09:30

If your bike is still backfiring then it is still running too lean in the pilot circuit. You said that you have already turned out the screw 2.5 turns, but it is still backfiring.
The solution is to richen the pilot circuit more.

-You need to get the next larger size pilot jet.

Putting in a larger "main jet" will richen the high range of the throttle (3/4 to full throttle), but will not help the backfiring...the pilot jet is the answer to fix the backfiring.

After you install the larger pilot jet, you will tune it again, and the adjusting screw should be set at about 1 to 1.5 turns out when tuned properly.

**There is a rule that says....if the adjusting screw is more than 2 turns out then you need a larger pilot jet...if the adjusting screw is less than 1 turn out then you need a smaller pilot jet....when tuned properly of course.

Title: Re: Blue flames in exhaust
Post by Savage_Rob on 03/13/06 at 06:54:14

It could also be exhaust leaks.

Title: Re: Blue flames in exhaust
Post by lancer on 03/13/06 at 07:27:24

True. I am assuming that the exhaust has been checked and is in good shape.

Title: Re: Blue flames in exhaust
Post by Bobster on 03/13/06 at 09:56:21

lancer wrote:

I just went from a 152.5 pilot, to a 155. And about 95 % of the backfire is gone. I already cleaned the old jet and dont see how that small of change made such a difference but im glad.

Title: Re: Blue flames in exhaust
Post by Bryner on 03/13/06 at 11:34:42

I'm waiting to thursday to change main jet for a 130 and make more test, because I'm still using the 125 main jet.

I will check exhaust leaks tomorrow too...

Thanks for all friends ;D