Check out carbparts.com. They have really good tuning tips on all types of carbs with good diagrams.

 

Backcountry, Free1steven:

HHHHHHEEEEEELLLLLPPPPPP!

I worked on my shee all night with no success. In fact, the problem has changed a bit.

I went to adjust the idle tonite and the plastic Idle Speed screw head broke off. I carefully drilled then extracted it out. I don't believe I damaged the screw input since a new Idle Screw went back in with no problem.

Anyway, my Idle Speed Screws have no impact on the idle speed. In fact, I can screw them all the way out and remove them, and the idle never changes. If I screw them all the way in, the speed increases just before they tighten all the way in.

The only way to change the idle speed is via the Idle Mixture Screw (small brass screw). To get the best idle, I have the screw only 1/4 turn out from fully closed (the screw is on the air intake side, ie: closed is rich, out is lean). If I turn the mixture screw out anymore than that, it idles way too fast.

What could the problem be? Is my Idle (Pilot) Jet too big or small? It is currently a 42.

If I install smaller Idle Jets, will that make it idle faster since the mixture will even become more lean? Or, should I install a larger Idle Jet to slow the idle speed down so I can open the Idle Mixture Screw up more?

Why aren't the Idle Speed screws having any impact on the idle speed?

Keep in mind that this problem came up after I put my new drag pipes on.

Like I said, hhhheeeellllpppp!

 

I would make sure that you were giving it enough fuel before and after your drag. You can seize an engine just as easy when letting off the throttle after a wide open run. Increase the pilot size and don't be concerned if it doesn't idle just right. Control your throttle response and crossover points with different needle shapes and sizes. You should not let a Banshee sit idling for long anyway. It can overheat.

 

Rob4092:
I also went w/ a pair of 35PWK's and have had no problems at all w/ idle or jetting. It took a little bit to get them dialed at first, but WOW! Its one of those things I wish I did a long time ago.
As for your idle/pilot problem..... Go to my web site and click on the link for jetting files. I uploaded 3 files for people that need a lil help w/ jetting. The are in .PDF format so you will need acrobat reader to view them. They are very detailed and help alot!

good luck
walter
88 banshee 370
95 Dodge Ram 4x4
99 Quadbuddy

 

You've got something else going on. Check that you don't have any airleaks first. Then I highly reccomend taking your carbs apart and blowing them out with compressed air and liberal application of carb cleaner while doing such. Re-assemble and start all over again. I know this sucks, but for you to go from 2 turns out running OK to all the sudden running like crap, something is amiss. Put fresh plugs in too. We'll get you there, keep up your tenacity and focus, it helps us that you are staying focused and wanting to get this right....

 

I also thought I may have an air leak, but cannot locate one. Could I have scarred the Idle Speed Screw threads up when I drilled it out and air is getting in through there? What exactly does that speed screw do...does it allow more air or fuel? Or does it simply bump into the slide and open it up a bit (similar to adjusting the slack out of throttle cable on the top of the carbs)?

I tried putting a tiny amount of plumber's tape on the Idle Speed Screw in case air was getting through, but it did not help.

Something I forgot to add was after putting the drag pipes on, I increased the Main Jets from 158 to 175 (up 7 sizes). I didn't change the Idle Jets at all. Should I increase them now to get more fuel? If so, how many sizes?

I am thinking that it needs a larger Idle Jet to get more fuel. My thought is since the Idle Mixture Screw is on the Air Intake side of the carb, screwing it in allows a richer fuel mixture. Since I get better response with the Idle Mixture Screw almost all the way in, maybe I need to increase the Idle Jet size?

Again, what exactly does the Idle Speed Screw do? Why would I obtain no change in idle speed by screwing it all the way out? I would think it would idle very high since air could get in without the screw in place. Is my thinking all wrong when it comes to the Idle Speed Screw?

I will take a look at B370's carb site in a bit. In the mean time, can you guys thinks of anything else? I sure appreciate the help!
HHHHHHEEEEELLLLLPPPPPP!!!!

 

On your PWK's the idle speed screws contacts the slide and prevents it from closing all the way. Which then will raise or lower the RPM's accordingly. With the screw almost all the way in
the slides should be lifted slightly allowing more air, this is what makes me think that it's rich.

Try the "choke-on-off" trick. By this, I mean start your bike. Warm it up. Then pull the choke on and try to very slightly rev your engine(1/8 or less throttle). If it balks and sputters, you're too rich. If it seems to get better then you're lean.

I suspect that you're rich right now. I would try the 40 pilot, but first blow your carbs out.

 

I will try your suggested Choke trick when I get home.

I am thinking that I may need a Richer Idle Jet since it seems to slow the idle down when I screw the Idle Mixture (Brass) Screw in all the way. With the Idle Speed Screw turned out, I am thinking it is not increasing the idle since it is already running as lean as it can, ie: no further adjustment will change it.

If the Idle Speed Screw area got scared up from extraction last night, could air be getting in there creating the lean condition?

I had Paul Turner pipes with 158 Mains before I put my Drag Pipes on and it was fine. When I put the Drag Pipes on, I bumped the Mains up to 175 because I was afraid it would be too lean.

Should I have increased the Idle Jets also so this doesn't run lean?

Can I access the Idle Jets from the bottom cap on the carbs or do I have to remove the entire bottom to get at them?

I am thinking that since it idles best with the Idle Mixture (Brass) Screw all the way in, it needs a Richer fuel mixture. The reason the idle won't slow down now may be because it is idling so lean????

What do you think?

 

It's possible that there could be a slight amount of air squeaking past the idle speed screw. It would be very small, and it's hard to say if it would be enough to cause problems. Plumbers tape or plain ole silicon would help seal any problems that you have.

The pilot jet is accessed via the lower portion of the carb. You have to take the float bowl off to gain good access to them.

Your pilot jet, of all the jets would likely to be the least influenced by swithcing pipes. I have found that sometimes with drag pipes the bike tends to start easier. Definately the case with my Honda.

Try the choke-on-off test to see how it is influenced. We'll go from there......

 

BACKCOUNTRY:

YOU DA MAN!!!

Well, I installed the 45 Pilots and blew out the carbs and guess what....all is well!

The Choke test sputtered out when I applied it. That is good! Shows I don't have an air leak somewhere! Great advice!

I really appreciate having both Backcountry and Free1steven on this site. You both save me (continually) a lot of $$$ and grief by coming to you with my problems and having you both solve them.

Lots of gratitude to you both...especially Backcountry!