Bike Is Together BUT Black Smoke And Flames!!!!

[doubledscar]

My bike has been sitting cause the plastic where getting painted. So while it sat i went threw the carbs. I got new needles and the new ones had an adjustable clip and after many posts and calling around i found to start in the middle position #3. Now i got it all back together and started er up and wow! I have a blackish Brownish smoke coming out the exhaust and when i let off the at high RPM i get a back fire and some flames out the exhaust. not good. So my question is what causes the flames and black smoke? Is it running to rich? Do i need to put the needle clip up? By the way its an 1989 Kat 600. Please help! I want to ride tomarrow finally!

[BucKatana]

Any backfire out of the exhaust is a rich fuel conditon.
Backfires through the carbs,onto the airbox, are a result of poor timing adjustment.


Could be anything from float levels set too high to a poorly installed jet.

How does the bike idle? Is there black smoke all the time at all throttle positions and rpms?



Buc

[doubledscar]

It idles great. I just set the floats when i went threw the carbs. It's only smokes like up over 9000 rpm. And backfires when i let off up that high. I think i may have the needle clip set to low. and the needle is not seating down far enought in the main jet.

[BucKatana]

It idles great. I just set the floats when i went threw the carbs. It's only smokes like up over 9000 rpm. And backfires when i let off up that high. I think i may have the needle clip set to low. and the needle is not seating down far enought in the main jet.

Ok......that would be the main jet most likely.

Try droping the needle down (Raising the clip ) 1st as it's the easiest of the two.

If it still presists then change the main to a smaller size.


Buc

[doubledscar]

I just went threw and changed all the main jets to the stock size.

[doubledscar]

Will that take care of the black smoke thing? or is that just from it sitting?

[BucKatana]

oopps.

Wait a min.
I thought you completely rejetted the carb.

If you only change the needles that's different.

are the needles the same as the OEM only with clip adjustments or do they have a different profile.
Needles have many different characteristis about them from dia,taper,lenght, straight dia lenght....etc.

If they are not they exact same as what was in there you will difinitely need to make adjustments.





Anyway.....drop the needle down 1 clip positon at a time and give'r a go.

If you get to the top clip position and it still behaves poorly......smaller mains will be required.

Buc

[BucKatana]

Just read your last few posts.


When jetting you should always make one change at a time otherwise you could run into problems because the multiple jet circuit overlap eachother and can create or mask a problem..


I guess I'd try going back to the orginal set up and go from there.

Does the bike have any other mods. ....pipe,filter..etc.



I'm just leaving work so I won't be able to reply for a few hrs.


sorry and good luck....


Buc

[doubledscar]

i just ordered new needles cause the ones i had in there where knicked. They are the same as stock but just have an adjustable clip position.

[BucKatana]

The mains you just put in....are they smaller or larger than what was in there???

[doubledscar]

They are smaller than the ones that where in there. I just moved the clip up and tried again but still black smoke and flames. But the throttle response is worse.

[BucKatana]

Well....without being there I'm at a loss.

Smaller jet,,,lowered needles,properly set float levels.......pfffffft.....I dunno!



I'll have to give this one some more thought.


Buc

[doubledscar]

Should i move the clip to the very top position? I set the pilot screws at 2 turns out on all of them. Is that correct too?

[BucKatana]

Ya...give that a go.

The pilot isn't doing much at 9000rpm but 2.5 to 3 truns is common.


I gotta to to bed...3am here.


Buc

[doubledscar]

Well 2.5-3 But i have my'n at two. Should i go two and a half.