Tuning XXX Carb w/ K&N Duel Intake

[PHATASS]

Tuning XXX Carb w/ S&S Twin Intake

Been trying to get some issues worked out and just can't seem to pinpoint the problem. My main issue is I can only get the scoot to idle smoothly with the air/fuel turned out 2.25 turns, anything less and it starts to die. Also have surging at low rpm's. Read through the S&S Carb Tuning, followed it step by step and also talked to Bob at XXX and he recommended bumping up the Int one size. Haven't seen to many people on here running a 34 Int??? He also recommended I turn the Accel pump out so that there is only 1 thread showing past the casting that holds the screw to help with the surging. Meanwhile it looks like my Stainless Creations Chaos II pipes are starting to turn blue/purple? I've checked for intake leaks and my plugs have a black ring around the base and porcelain is white after 100 miles. Looking for any advice. Here are my current settings.

2007 Big Dog K9
80 Main
33 Intermediate
46 Air Bleed
S&S Dual Runner Intake
XXX G Carb w/ Bore and Kit Mod
Stainless Creations Chaos II Exhaust
2.25 out on Air/Fuel
4 out on Accel Pump
Sea Level

 

[V]

Just right off hand it sounds like you might have a air leak to check for. They don't make a .34 intermediate. It skips from 33 to 36 and then to 40. I dont think you need the 36.

Might try squrting some break cleaner at the gaskets to see if the idle changes any.

Thats my first thought. I'm runnin XXX G 33 inter with 78 main. 590 cam.

 

[PHATASS]

Just right off hand it sounds like you might have a air leak to check for. They don't make a .34 intermediate. It skips from 33 to 36 and then to 40. I dont think you need the 36.

Might try squrting some break cleaner at the gaskets to see if the idle changes any.

Thats my first thought. I'm runnin XXX G 33 inter with 78 main. 590 cam.

That's what I thought too but sprayed carb cleaner around every gasket and no change in rpm. I found a website that has a 34 Int for S&S carbs but wanted to get a few more opinions first.

Product List

 

[V]

That's what I thought too but sprayed carb cleaner around every gasket and no change in rpm. I found a website that has a 34 Int for S&S carbs but wanted to get a few more opinions first.

Product List

Interesting didn't know they were available!

 

[wyatt580]

Yea you can get any size jet. Just not as common not to many people need any thing larger than 33 ..what about the airbleed go up four sizes . Takes alot to notice a change on that . Don't think this matters but the main sounds high. Mine has 33 inter 76 main 68 airbleed . I had same problem lots of surgeing especially at 2000 - 2500 rpm what really fixed it was taking carb apart and cleaning it for all the crap petrol and shit in the tank. Then set your adjustments per s&s instrutions no more surging for me

 

[Raywood]

I would shut your accelerator pump completely off. There may be an issue of it leaking and causing this issue. Some others have had this issue. You shouldn't ever need anything over the 33 for a stock motor

 

[RCAdd1ct]

That's what I thought too but sprayed carb cleaner around every gasket and no change in rpm. I found a website that has a 34 Int for S&S carbs but wanted to get a few more opinions first.

Product List

From what I hear that brake clean and carb cleaner have had the law after them and they are no longer a good test for leaks.

I was told starting fluid is the new leak tester product.

Like I said I was told...haven't looked first hand, but thought I would share what I was told.

 

[aspen874]

I have the same set up, Triple XXX carb and dual runner intake. I had my bike dynoed
and ended up with 34 and 80 on the jets. My bike had around 6500 mi. at the time, it
now has around 11,000 and the bike has ran great since

 

[PHATASS]

I have the same set up, Triple XXX carb and dual runner intake. I had my bike dynoed
and ended up with 34 and 80 on the jets. My bike had around 6500 mi. at the time, it
now has around 11,000 and the bike has ran great since

Thanks for all the info. Looks like I'll be ordering the 34 Int to try. That would explain why my air/fuel is 2.25 turns out and is trying to compensate for the lean intermediate.

 

[V]

From what I hear that brake clean and carb cleaner have had the law after them and they are no longer a good test for leaks.

I was told starting fluid is the new leak tester product.

Like I said I was told...haven't looked first hand, but thought I would share what I was told.

I have used ether in the past but just the fumes into or around the air cleaner affect the engine speed and it defeated the purpose of the air leak (intake gasket) that I was tryin to find.

But it is fun as hell to throw a can of it into a fire thou :roll:

 

[PHATASS]

I have the same set up, Triple XXX carb and dual runner intake. I had my bike dynoed
and ended up with 34 and 80 on the jets. My bike had around 6500 mi. at the time, it
now has around 11,000 and the bike has ran great since

Any chance you can check and see how many turns out you are on the fuel/air mixture? Thanks!

 

[aspen874]

I am mechanically challenged, but if you tell me how to check it, i will give it try.

 

[PHATASS]

Just turn the Fuel/Air Mixture screw (CIRCLED RED) in clockwise counting the number of turns until it LIGHTLY seats and that's the number I need. Remember that number and then turn it back out however many turns you turned it in and you'll be back to where you started.

 

[Tom Chop]

Tuning a Triple XXX Carb on PHATASS` K9

:flag: Sometimes these bikes can be exaspirating, but if you think through your problem the solution becomes clear. My K9 started exhibiting a different problem but the solution was very similar to yours. I started to notice a pinging noise out of my scoot at 2500-4000rpm. I`m running a set of V&H BR`s, a 0.600" cam, a modified S&S carb, and a Speed`s Performance-Plus Intake/Air Filter. The culprit in my case was the "fine" quality of gas we all are forced to use these days. My jets were similar to anyone else but when the engine was hot I was afraid to ride for the horrible pinging noise and damage it might cause to my beautiful Big Dog K9`s motor.
After I sat and contemplated the solution seemed to be to fatten-up the motor, at least the low and intermediate speeds. Here`s what I ended-up with; Intermediate-0.34", "Air"-0.60", and Top-0.82", Acelerator Shot 3.5 out, and Idle 1.125 out. That`s what works on Tom Chop`s K9.
Be Kind
Take Care
Tom Chop

 

[aspen874]

Brian, 1.25 turns on the fuel/air. thanks for the photo, I hopes this helps, soory i took so long to get back to you. I took the dog out today on The Polar Bear ride today here in
St. Louis and it ran great, 23 degrees. I would also recommend the Thunder Heart ignition, you can tell the differnce

 

[PHATASS]

Brian, 1.25 turns on the fuel/air. thanks for the photo, I hopes this helps, soory i took so long to get back to you. I took the dog out today on The Polar Bear ride today here in
St. Louis and it ran great, 23 degrees. I would also recommend the Thunder Heart ignition, you can tell the differnce

Perfect!! Looks like I'll be getting the .034 before heading to the dyno next week.

 

[wyatt580]

How did this ever turn out????

 

[aspen874]

Brian, I am curious too, did the 34 intermediate work?

 

[Germanbiker]

Also got the xxx carb.

Have an open German made exhaust, K&N with modified BDM Cover (lower part is drilled off and front is open).

The 33 is a little too lean, asked Bob about a 34 and 35 - he can make these and send them to me.....

Got a 60 air bleed and 78 main. Bike runs great - no Harley competitors here in Germany - all blown :2thumbs:.

Jochen

 

[PHATASS]

Brian, I am curious too, did the 34 intermediate work?

Didn't take it to the dyno but noticed after installing the 34 intermediate, my gas mileage dropped to about 32 mpg. Was getting 38 mpg with the 33 intermediate. Still have to turn the air/fuel screw out 2.25 turns and still have the surging. Talked to Bob at xxx again and said to check the taper at tip of the idle mix screw and make sure it isn't flat. This would cause a false reading resulting in the air/fuel screw to be turned out further than normal. He also said most of his carbs are now running a #60 slow jet so I'm going to swap out my current #46 to see the difference even though I don't have any problems with the transition from slow to main at this time, just curious. I have the carbs apart now for a good cleaning so I am also going through all the seals to check the condition to try to elimate the lean surging.