Jetting

[TeamRealtreeHD]

The bike was running absolutely wonderful after the rings set in, and I had 2 tanks through it yesterday.

 

But the pilots were a little high... Kevin recommended 50's and I had 52's in with 160 mains. The mains were close I think with those pilots.

 

But here is the situation... many might be able to crack this puzzle right away. I put 48 pilots in, and now it is breaking up a bit in the higher rpm's, which it wasn't before. I believe that is a main probelm. Now remeber, I still have the 160 mains in after I made that swap from 52 to 48 pilots.

 

I had my 160 mains and 48 pilotsin, and it was idling better and responding better on the throttle parked when I gave it gas. So I believe the pilots are on. That is good.

 

But the main I believe is a little big. 155 mains with 52 pilots ran lean. But what about 155 mains with 48 pilots?

 

When I did my test today, I ran it with the air screws 2 turns out.

 

Where should my air screws be with my mods in my sig?

 

Basically what do you guys think for mains, pilots and air screw turns? I think the pilots are good, and I also believe that the mains need to be down not to the 155 range, maybe a littel richer, but I don't know. Definately less than 160...

 

And what about the air screws?

[TeamRealtreeHD]

If nobody can help on the jetting, can someone give advice on the air screws?

[TeamRealtreeHD]

It was running a little rich with 52 pilots, 160 mains, and the air screws out 1.5 turns.

[BellicoseBanshee]

First of all, I don't think you understand how the circuits work in the carburetor.

 

Main jet: The main jet controls fuel from about 3/4 throttle to WOT. When the throttle is opened far enough, the needle is pulled far enough out to allow the main jet to regulate fuel flow.

 

Jet needle: The jet needle (the needle) controls fuel flow from about 1/8 throttle to 3/4 throttle. Most of the tuning is done with the jet needle and not the needle jet.

 

Needle jet: The needle jet is the hole the needle slides into. the needle jet and jet needle work together to regulate fuel flow. Most of the time, adjusting/changing the jet needle is sufficient to tune the affect range.

 

Slide valve: The slide valve controls fuel from about 1/8 through 1/2 throttle (greatest affect on 1/8-1/4). The cut away determines the size of the slide. Usually not necessary to change this.

 

Pilot jet: The pilot jets works with the air screw to regulate fuel at low throttle settings, about 0-1/4 throttle.

 

Each circuit is adjusted independently and they overlap at times provide proper jetting at all throttle positions. It is best to adjust one circuit at a time and I prefer to start with the mains and work my way down to the pilot.

 

AIR SCREW: Warm up your engine, then adjust the idle slightly higher than normal. Turn the airscrews in until they seat and then back them 1/4 turn and let the engine stabilize. Keep turning the airscrews out a 1/4 turn at a time, allowing the engine time to stabilize between changes, until the engine reaches its highest RPM. The air screws should be between 1 and 2-2.5 turns out. If the highest RPM is less than 1 turn (lean), install a larger pilot jet. If the highest RPM is more than 2-2.5 turns out (rich), install a smaller pilot.

 

If I were you, I would verify the pick-up is gapped correctly, then start with the mains and work your way down to the needle, then finish with the pilot. It can be time consuming, but worth the effort in the end. Also, make one change at a time while troubleshooting a jetting issue, for it will make the process much easier.

 

 

DISCLAIMER: I am not a jetting expert, I only know what works well for me...

[TeamRealtreeHD]

The bike ran good with 160 mains and 52 pilots, only complaint was the missing a little when it went from idle to 1/4.

 

I switched the hets from that setup to 158 mains and 50 pilots, and it is running awesome. Sarts right up, doesn't miss anywhere across the board, and the plugs look very good. Light brown.

 

That is the jetting the Kevin recommended, and I was a little richer before.

 

The bike is running awesome. I am going to have a few buddies send their jugs to kevin as he made this thing scream, he really did.