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Author Topic: Jetting with EFI silencer  (Read 903 times)

Samir72

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Jetting with EFI silencer
« on: July 26, 2013, 02:22:26 PM »
Hey guys,

I'm installing the EFI silencer on my 09 Bullet Chrome AVL. It has a K&N air filter as well.
I ordered a few jets from our host with the silencer since I imagine it needs to get re-jetted a little.

Where do I start in terms of the various jets/sizes?
What's the procedure?

Any help is appreciated!

Thanks,

Samir

Samir72

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Re: Jetting with EFI silencer
« Reply #1 on: July 28, 2013, 01:32:21 PM »
I can't locate a RE shop in the area, since the carb is Japanese will a Japanese shop be proficient getting this bike jetted correctly once the new silencer goes on? Or will they not work on indian made bikes just out of principle?

High On Octane

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Re: Jetting with EFI silencer
« Reply #2 on: July 28, 2013, 02:58:23 PM »
What carb are you currently using?  If it's a Mikuni you should be able to go to any motorcycle parts store and they should have an ample supply of the jets you need.

Scottie
Bulldog Kustoms - Denver
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The Blackhawk
1958 Enfield/Indian 711cc Twin

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Samir72

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Re: Jetting with EFI silencer
« Reply #3 on: July 28, 2013, 03:04:00 PM »
It's a Mikuni CV BS29, since I've never taken it to a shop, what price range should the actual re-jetting be in? I ordered  number of jets from our hosts as well.

High On Octane

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Re: Jetting with EFI silencer
« Reply #4 on: July 28, 2013, 03:53:53 PM »
I don't know for sure, I do all my work myself.  I REFUSE to let a shop touch my bike or cars.  Depending on where you go, jets are usually $5-$9 each, and they are super easy to change out.  And honestly, it is something you should learn to do on your own if you own a carburated motorcycle.  Correct carb tuning is essential for the proper running of your bike and also to prevent catastrophic engine damage.  If I'm not mistaken, fuel conditions tend to go lean as you open up the engine and allow it to breath better.  What you will want to do is pull out your current main jet from the bottom of the carb, usually you can do this without removing the carb.  Just make sure you have a cup to catch the fuel that will drain out.  Once you have that jet removed and can see what size it is (it will be stamped on the side of the jet somewhere) take into the parts store and buy 1-3 jets in the next larger sizes, usually you will only need to increase it 1 or 2 sizes.  After that, go out and do some plug chops and see where you're at.  Just for reference, it only takes me 2 minutes to change out the main jet on my Amal carb.

Scottie
Bulldog Kustoms - Denver
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The Blackhawk
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Samir72

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Re: Jetting with EFI silencer
« Reply #5 on: July 28, 2013, 04:02:46 PM »
Thanks Scottie,

I ordered a few different main and pilot jets from nfieldgear and I have taken the carb apart and put together before, so I'll give it a go.

You guys use the term "plug chops" a lot 'round here but I was hoping you could point me to a worthy tutorial so I can learn what it actually means to do plug chops ;)

Thanks for all your patient replies,

Samir

High On Octane

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Re: Jetting with EFI silencer
« Reply #6 on: July 28, 2013, 04:35:22 PM »
I was unfamiliar with plug chops before this forum myself.  Plug chops is a technique used to determine and isolate the the tuning of the different stages of throttle in the carburater.  It is used as a guide to determine if you are running rich, lean, or just right through inspection of the spark plug.

This is the response I received from ace.cafe when I asked about plug chops:

Quote
Plug chops are a way to isolate each major throttle position's mixture setting, by isolating the jets which control the mixture in those throttle positions. With these types of carburetors, you can be lean in one throttle position, and be rich in another. This process allows you to tune each throttle range and the corresponding jets.

The process is like this.
Put a piece of tape or other indicator pointer on your throttle housing, like an arrow pointer.
Put a piece of tape wrapped around your throttle grip. Then use a magic marker on the tape to mark the 1/4, 1/2, 3/4, and Full throttle position, so that they correspond with the pointer when you are at these throttle positions.

Use a new plug.

Then, take the bike out and ride at one of these throttle positions for a few minutes so that the plug can get enough time to get its color. Hold it at that throttle position the whole time without changing it, so that it isolates that throttle position only. When you get to a safe place to pull over to check the plug, cut the engine and pull in the clutch, don't change the throttle position until the engine stops,  and coast to a stop on the side of the road and check your plug for color.
If the color is a medium tan, or something around that, it's pretty good for that throttle position, and you can try the next throttle position, etc.

Throttle positions and their corresponding jets are:
Idle = Pilot jet and bleed screw
1/8 = Throttle slide cutaway
1/4 = Needle jet mostly
1/2 = Needle jet and jet needle combination(they actually overlap in function from 1/4-3/4)
3/4 = Jet needle mostly
Full = Main jet

Doing this will give good even throttle results with proper mixture settings all thru the whole throttle range, and should eliminate any hiccups, bogs, or flat spots in the entire throttle range, and prevent lean conditions from causing engine damage, and keep your fuel economy at its best.
Bulldog Kustoms - Denver
Specializing In Kustom Paint

The Blackhawk
1958 Enfield/Indian 711cc Twin

Building The 1st Ever Ace Performance Twin

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Samir72

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Re: Jetting with EFI silencer
« Reply #7 on: July 28, 2013, 05:13:09 PM »
Sounds challenging, but I'll do my best.

Would you need to clean the plug each time? How would you best clean it?

I have to ask, can this be done in neutral without riding the bike?


ERC

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Re: Jetting with EFI silencer
« Reply #8 on: July 28, 2013, 06:26:12 PM »
You have to ride the bike. Or put it on a dyno.   ERC
2-57 Apaches, 2-57 Trailblazers, 60 Chief, 65 Interceptor, 2004 Bullet, 612 Bullet chopped.

High On Octane

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Re: Jetting with EFI silencer
« Reply #9 on: July 28, 2013, 07:57:47 PM »
I use a small wire brush and either carb or brake cleaner to rinse it off after scrubbing.  And it's not that challenging, it sounds overwhelming,  but when you break it down to the individual steps it's pretty straight forward.  The most difficult part is not burning yourself handling the spark plug.    ;)

Scottie
Bulldog Kustoms - Denver
Specializing In Kustom Paint

The Blackhawk
1958 Enfield/Indian 711cc Twin

Building The 1st Ever Ace Performance Twin

Join My Facebook Group!
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1 Thump

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Re: Jetting with EFI silencer
« Reply #10 on: July 28, 2013, 08:21:57 PM »
The only reliable way to tune a carb is on a dyno. It is quick but does cost a few pennies. If it is a stock BS29 carb with the typical free flow muffler-filter mods then there is enough jetting info on this board to put you in the ball park.  Heck, you may not even need a dyno tune.

Question: What are you trying to accomplish ?

Samir72

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Re: Jetting with EFI silencer
« Reply #11 on: July 28, 2013, 08:40:37 PM »
1 Thump: I bought the bike in 2010, it ran well even with the big stock exhaust. It already had a K&N air filter. Shortly after the catalytic converter failed and the guy I bought it from replaced the exhaust with a used free flowing unit and the troubles began... Too rich, too lean, too this, too that...
He ended up drilling some of the jets in an attempt to get it right, but the bike just hasn't run well ever since then. That was 4000 miles ago, I have ordered a few jets and the EFI silencer from nfieldgear. All I want is for the bike to run well again. I'm afraid I did some damage to the engine by running it with the wrong air/fuel mixture for so long.

I want to accomplish a little more performance on a well tuned bike.

This is my first bike and I'm quite frustrated...

High On Octane

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Re: Jetting with EFI silencer
« Reply #12 on: July 28, 2013, 09:19:50 PM »
If the PO drilled out the jets I guarantee it was running way too rich which won't cause engine damage, just foul out your plug often.

As 1 Thump said, there is plenty of info on here for the exact set up you have.  Trying looking in Tech Tips, I've seen a lot of info in there.

Scottie
Bulldog Kustoms - Denver
Specializing In Kustom Paint

The Blackhawk
1958 Enfield/Indian 711cc Twin

Building The 1st Ever Ace Performance Twin

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1 Thump

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Re: Jetting with EFI silencer
« Reply #13 on: July 28, 2013, 10:54:37 PM »
OK. Like Scottie said too rich will not hurt the bike in the short run. In the long run it will carbonize the head leading to elevated compression, depends on how rich it is. That jet-kit from nfieldgear will have all the jets you need. Start with a 20 pilot and 130-135 main, then gradually lean down from their. It WILL be rich but your bike will start and run. Is your needle in the stock position ? Do you still have the hotpipe (its a long restrictive perforated pipe in the header pipe (bend pipe).

Samir72

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Re: Jetting with EFI silencer
« Reply #14 on: July 28, 2013, 11:01:05 PM »
the hot pipe is actually inside the header pipe? How would I find out if it's there? Do I need to take the header pipe off?
I didn't get the whole kit, I got the 2 next sizes up from stock on the main and pilot, as per Tim's suggestion at nfieldgear.