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Message started by odvelasc on 07/07/09 at 07:13:50

Title: Black smoke when throttling at at idle
Post by odvelasc on 07/07/09 at 07:13:50
Hello all,

After the bike has reached running temp I get a bit of black smoke when throttling at idle. Mainly having idled at a stop light for a bit. It smells a bit rich. The black smoke comes when I throttle from closed to about 1/4 throttle. Any idea what circuit I should be modifying? I have a 15pilot jet bled out to the max size hole, a 160 main jet, and the dial a jet set to the second richest setting. I have my needle set to the middle position. I find that if I lower it the bike does not smoke but the throttle response is not as good. My air mix is about 2.5 turns out (out is lean on the vm). Perhaps leave the needle setting and try a main jet smaller or down one size in the dial a jet(used for rejetting)?

Title: Re: Black smoke when throttling at at idle
Post by bill67 on 07/07/09 at 10:49:26
 If you jet any motorcycle for max power its only good at a drag strip,It will be to rich for normal driving.It will foul plugs and use a lot of gas.

Title: Re: Black smoke when throttling at at idle
Post by odvelasc on 07/07/09 at 11:28:38

6A6164643E3F080 wrote:
 If you jet any motorcycle for max power its only good at a drag strip,It will be to rich for normal driving.It will foul plugs and use a lot of gas.


Makes sense.

Title: Re: Black smoke when throttling at at idle
Post by Digger on 07/12/09 at 20:45:00

4F4456454C415343200 wrote:
Hello all,

After the bike has reached running temp I get a bit of black smoke when throttling at idle. Mainly having idled at a stop light for a bit. It smells a bit rich. The black smoke comes when I throttle from closed to about 1/4 throttle. Any idea what circuit I should be modifying? I have a 15pilot jet bled out to the max size hole, a 160 main jet, and the dial a jet set to the second richest setting. I have my needle set to the middle position. I find that if I lower it the bike does not smoke but the throttle response is not as good. My air mix is about 2.5 turns out (out is lean on the vm). Perhaps leave the needle setting and try a main jet smaller or down one size in the dial a jet(used for rejetting)?


Od,

In addition to your other checks, I'd be inspecting the operation of the petcock.

Title: Re: Black smoke when throttling at at idle
Post by odvelasc on 07/13/09 at 19:23:24

624F41414354260 wrote:
[quote author=4F4456454C415343200 link=1246976030/0#0 date=1246976030]Hello all,

After the bike has reached running temp I get a bit of black smoke when throttling at idle. Mainly having idled at a stop light for a bit. It smells a bit rich. The black smoke comes when I throttle from closed to about 1/4 throttle. Any idea what circuit I should be modifying? I have a 15pilot jet bled out to the max size hole, a 160 main jet, and the dial a jet set to the second richest setting. I have my needle set to the middle position. I find that if I lower it the bike does not smoke but the throttle response is not as good. My air mix is about 2.5 turns out (out is lean on the vm). Perhaps leave the needle setting and try a main jet smaller or down one size in the dial a jet(used for rejetting)?


Od,

In addition to your other checks, I'd be inspecting the operation of the petcock.[/quote]

Petcock is good. Well I am using the stock running it on Prime. Perhaps when sitting at a stop too long or in heavy stop and go traffic too much fuel is delivered for the idle. I should get around to that raptor 660 petcock lol Also, I went down one dial on the dial a jet and turned that air screw out another quarter turn. Seem pretty good now, and not as stinky.

Title: Re: Black smoke when throttling at at idle
Post by LANCER on 07/14/09 at 02:54:00

2D2634272E233121420 wrote:
Hello all,

After the bike has reached running temp I get a bit of black smoke when throttling at idle. Mainly having idled at a stop light for a bit. It smells a bit rich. The black smoke comes when I throttle from closed to about 1/4 throttle. Any idea what circuit I should be modifying? I have a 15pilot jet bled out to the max size hole, a 160 main jet, and the dial a jet set to the second richest setting. I have my needle set to the middle position. I find that if I lower it the bike does not smoke but the throttle response is not as good. My air mix is about 2.5 turns out (out is lean on the vm). Perhaps leave the needle setting and try a main jet smaller or down one size in the dial a jet(used for rejetting)?


black smoke when throttling at idle:   rich in the pilot circuit

15pilot jet:  I assume that you have a UFO installed  ? ?   If so, did you drill the little hole in the top of the needle jet that sticks up into the carb throat as described in the instructions  ?  You should drill the largest size hole listed in the recommendations.  If you still have issues after that then PM  me.

160 main jet, and the dial a jet set:  wrong main jet for using the dial-a-jet (DAJ).  The DAJ is designed to take over the jetting task for the main jet circuit, and the main jet should be reduced about 3-4 jet sizes so the DAJ can work properly.  With the #160 installed your DAJ is not doing anything.  Take the main jet down to #150 and leave the DAJ on the 2nd setting.

needle set to the middle:  The DAJ works the this circuit as well so I would move the clip to the top slot to start with and see how she goes.
The UFO also works the middle range so there is help from that side too.

Adjust the pilot screw again after you make the changes.
The UFO creates a really strong pull on the fuel supply, thus making for the rich mix, and it does require significant alteration to the NJ with the drilled hole to lean it back to a proper mix.
Once you get this dialed in correctly the engine will take off like a jet.

Title: Re: Black smoke when throttling at at idle
Post by odvelasc on 07/14/09 at 08:15:49

2429262B2D3A7A7F480 wrote:
[quote author=2D2634272E233121420 link=1246976030/0#0 date=1246976030]Hello all,

After the bike has reached running temp I get a bit of black smoke when throttling at idle. Mainly having idled at a stop light for a bit. It smells a bit rich. The black smoke comes when I throttle from closed to about 1/4 throttle. Any idea what circuit I should be modifying? I have a 15pilot jet bled out to the max size hole, a 160 main jet, and the dial a jet set to the second richest setting. I have my needle set to the middle position. I find that if I lower it the bike does not smoke but the throttle response is not as good. My air mix is about 2.5 turns out (out is lean on the vm). Perhaps leave the needle setting and try a main jet smaller or down one size in the dial a jet(used for rejetting)?


black smoke when throttling at idle:   rich in the pilot circuit

15pilot jet:  I assume that you have a UFO installed  ? ?   If so, did you drill the little hole in the top of the needle jet that sticks up into the carb throat as described in the instructions  ?  You should drill the largest size hole listed in the recommendations.  If you still have issues after that then PM  me.

160 main jet, and the dial a jet set:  wrong main jet for using the dial-a-jet (DAJ).  The DAJ is designed to take over the jetting task for the main jet circuit, and the main jet should be reduced about 3-4 jet sizes so the DAJ can work properly.  With the #160 installed your DAJ is not doing anything.  Take the main jet down to #150 and leave the DAJ on the 2nd setting.

needle set to the middle:  The DAJ works the this circuit as well so I would move the clip to the top slot to start with and see how she goes.
The UFO also works the middle range so there is help from that side too.

Adjust the pilot screw again after you make the changes.
The UFO creates a really strong pull on the fuel supply, thus making for the rich mix, and it does require significant alteration to the NJ with the drilled hole to lean it back to a proper mix.
Once you get this dialed in correctly the engine will take off like a jet.[/quote]

I have it the NJ drilled to the largest hole, the DAJ to the middle setting, and I will go get a new main and readjust my carb. It may a few days because I am working some overnights and sleep all day.
Thanks for the info.

Title: Re: Black smoke when throttling at at idle
Post by odvelasc on 07/15/09 at 17:30:26
I have a 155 I believe in the carb now. I found one of my old main jets. It shows 15 because the last number wore of from wrenching it out lol. I ohave a 150 on order. I had the daj set to the second most lean setting and she runs worse than when I had the 160 main. I am at work now and set it to the second most rich setting because the drive to work on the slab was crappy. She did not have enough fuel top end to drive well. She struggled to reach 65mph. The difference in pull at the bottom end was negligible. We will see when the 150 main comes in on Monday.

Title: Re: Black smoke when throttling at at idle
Post by Digger on 07/16/09 at 21:27:21

4E4557444D405242210 wrote:
[quote author=624F41414354260 link=1246976030/0#3 date=1247456700][quote author=4F4456454C415343200 link=1246976030/0#0 date=1246976030]Hello all,

After the bike has reached running temp I get a bit of black smoke when throttling at idle. Mainly having idled at a stop light for a bit. It smells a bit rich. The black smoke comes when I throttle from closed to about 1/4 throttle. Any idea what circuit I should be modifying? I have a 15pilot jet bled out to the max size hole, a 160 main jet, and the dial a jet set to the second richest setting. I have my needle set to the middle position. I find that if I lower it the bike does not smoke but the throttle response is not as good. My air mix is about 2.5 turns out (out is lean on the vm). Perhaps leave the needle setting and try a main jet smaller or down one size in the dial a jet(used for rejetting)?


Od,

In addition to your other checks, I'd be inspecting the operation of the petcock.[/quote]

Petcock is good. Well I am using the stock running it on Prime. Perhaps when sitting at a stop too long or in heavy stop and go traffic too much fuel is delivered for the idle. I should get around to that raptor 660 petcock lol Also, I went down one dial on the dial a jet and turned that air screw out another quarter turn. Seem pretty good now, and not as stinky.[/quote]

Od,

To completely exonerate the petcock (for a rich condition), you may want to try the following:

Crimp the petcock vacuum line.  Crimp it tightly enough so that nothing can flow through it, not even air.

Put the petcock on PRI.  If the bike runs better, that means you probably have a defective petcock.  You may still have other problems, but the bike will not run right until you deal with the defective petcock.

Happy hunting!

Title: Re: Black smoke when throttling at at idle
Post by odvelasc on 07/17/09 at 06:46:38
Nothing wrong with the petcock. How do I know this? Well I damaged my fuel line a while back. Also, I had lost the clear, plastic tube that served as the filter for the DAJ. So, I purchased a whole new roll of that tubing to cut off a piece and use as a filter tube for the DAJ. So, when I damaged my fuel line I used this clear tube as a replacement. Works great, no leaks.  Now to the kewl part. I needed to rejett yesterday, sooo I ran on the bike in the ON position in order to burn off what was left in the float bowl. Nothing was coming down the fuel line when in the off position. Soooo, my petcock is A. Ok  8-)

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