Jetting Issues

[Newcs222]

Ive just installed a stage 2 dynojet kit on my Banshee. I have full fmf exhaust and k&n filters. It recommended I use the 280 main and needle at second notch from the top as I am below 3000ft. I've got the air adjust screw 1 1/2 turns out. I've got it to idle good and I'm thinking the main is fine as well because after 2000rpm or so it rides good. The problem I have is when I try and accelerate fast it bogs. Also at idle it will bog and take longer than normal to idle back down. Would this mean I'm running lean on my pilot jet. Do I adjust the air adjust screw to 1 turn to run rich. I have been adjusting the air adjust but it doesn't seen to be making too much of a difference. Thanks for your help. 

[Atomic Monkey]

Had the same problem, ended up roughly 1/2 turn out... looking at different pilots.

[Newcs222]

Had the same problem, ended up roughly 1/2 turn out... looking at different pilot

So at 1/2 turn your shee runs good? Do you have to be concerned at 1/2 turn out or it it okay? What would be the next size pilot? 30?

[Atomic Monkey]

For me it got rid of the bog, and the plugs looked good. Guess I was more concerned about what the lean condition would do over how many turnes were on the screws. It was recommended to me to change the pilot because of the reeds I just got. Plus I'm running good with a 330 mains, so I'm guessing we're dealing with 2 different kind of animals.

Guess what I'm saying is that it can't hurt to try, but maybe the experts can give you better direction on what pilots to run if you find that richer helps

[sleeper06]

Those pipes like 30 pilots and rich on the needle with no lid I would go all the way rich meaning furthest clip from blunt end and go from there main should be close

[Newcs222]

Those pipes like 30 pilots and rich on the needle with no lid I would go all the way rich meaning furthest clip from blunt end and go from there main should be close

I'll order up a couple 30's and maybe a couple 27.5's? I've got it second furthest from blunt end. I'm not running an air box. Just two k&n's. Also running boysen reeds. Should I change that as well? Runs good at higher rpm.

[Atomic Monkey]

I would do what sleeper06 says, I've been really impressed with the advice he gives.

As long as your reeds still have a good seal, I wouldn't worry about them. Pull your needle all the way up, get your 30 pilot in, and go from there like the man says.

My only advice from there is to make any changes one step at a time, and give things a chance to settle in.

 

And it could be just me, but I always like to make sure my float and fuel levels are right and even between the carbs, and that the carbs are synced. I do alot of my idle and off idle settings with the gauges on, checking to make sure the pipes are about the same temp, and that the "snap" of the exhaust is the same from side to side.

I am by no means an expert, just sharing what I do, and what's important to me for getting a good base to tune from. 

 

On a side note, I ran Boyesen 2 stage on ported stock cages since I got my machine, just upgraded to VF4s as part of a rebuild. I've run the Boyesens in dirtbikes and snowmobiles too, they're ok, but there's just better technology and research now. I haven't run the VF4s yet, but I can't wait!

[Strm Trpr]

Go with what sleeper06 said for jets.

Is the TORS eliminated from the carbs?

Do you have idle screws installed?

And if you want to tune your motor tits get a cheap tach from eBay.

http://www.ebay.com/itm/360856901363?redirect=mobile

Get a Carb Sync Tool from FAST.

http://www.farmandsandtoys.com/partdetail.asp?partid=59

Then Google how to Sync a pair of Banshee carbs.

2 grooves down from the blunt end lowers the needle and makes the carb lean.

Airscrew 1/2 turn out means your pilot jet is too small.

What's your elevation and avg air temps?

[Newcs222]

Go with what sleeper06 said for jets.

Is the TORS eliminated from the carbs?

Do you have idle screws installed?

And if you want to tune your motor tits get a cheap tach from eBay.

http://www.ebay.com/itm/360856901363?redirect=mobile

Get a Carb Sync Tool from FAST.

http://www.farmandsandtoys.com/partdetail.asp?partid=59

Then Google how to Sync a pair of Banshee carbs.

2 grooves down from the blunt end lowers the needle and makes the carb lean.

Airscrew 1/2 turn out means your pilot jet is too small.What's your elevation and avg air temp

Yes Tors eliminated with slide adjust screw. I've got 30's on the way. Carbs are synced using the site glass as well as air filters removed to visually see the slides synced. 

[Strm Trpr]

Yes Tors eliminated with slide adjust screw.

I've got 30's on the way.

Carbs are synced using the site glass as well as air filters removed to visually see the slides synced.

 

Sounds to me like you have it all figured out.

[Strm Trpr]

Truely, it is much better to use the FAST Sync Tool.

I know it's a lot to spend on a non performance part/tool, but I think it's very important for optimum power/performance.

The sync tool measures how much vacuum the motoring is ingesting.

Jetting needs to be very close when doing this, especially the pilot and needle.

1.5 turns out on the airscrew is a good starting point.

Setting idle with a tach to 1550+/-50rpms while using the sync tool is what I found works best.

You can dial in your idle to a specific rpm and then tweak the idle screws to get the vacuum perfectly matched for each cylinder.

You can test your airscrew adjustments by snapping the throttle open fast, if it boggs, give it a turn in to give it  more fuel, then check your vacuum again.

When you put your filters back on, the idle should slow about 50rpm or so.

 

Another important part of tuning is part throttle tuning.

If your slides do not lift off at exactly the same instance, they will continue to be that much off throughout the entire powerband.

Dialing in the cable adjusters on top of the carbs when you do a TORS elimination is a must.

The new throtle cable is not built to the exact specs an OE throttle cable is when used in conjunction with the TORS boxes.

 

To sync the carbs at part throtle, use the sync tool and the tach and rev the motor and hold it at 6000rpms or so and adjust the cables on top of the caps to acheive matching vacuum.

Have someone help you hold the throttle perfect or what I do is pull the cable sheath out of the free length adjuster at the thumb throttle and lean it on the adjuster end.

I put a wooden tooth pick into the adjuster so the cable sheath doesn't fall back into the adjuster.

From here you can use the adjuster to finely set your high rpm idle of ~6krpm.

 

If you're in an area with limited airflow through the radiator, put a fan in front of the radiator so you don't get the motor hot while tuning, ask me how I know this...

 

It's really very easy, and you'd be surprised what an 1/8 of a turn on the idle screws or cable adjuster will do to the amount of vacuum the motor ingests...

 

My $.02

 

[tdod101]

The sync tool from Jeff is awesome, I tune all my dual carb machines with them. Even help my friends if they ask nice. For $50 it's worth every penny.

[Sandking]

If you open the thumb throttle you can use a socket to hold the throttle open part ways to measure the slides being open

 

Sent from my SCH-I535 using Tapatalk

[Atomic Monkey]

I completely agree with strm trpr on the value of getting the carbs in sync.

I use a motion pro sync tool, and tap into where the crossover tube is in the intake, removing the tube and using adapters.