Changing Pipes and Jet Question - Honda Shadow

[markdh]

I have a Honda Shadow... was thinking of doing a pipe change over the winter. Question I have is about jets. I've heard alot of people say that you dont need to have the jets redone, others say for sure you do.

1) do you really need to get the jets redone?

2) if you do, how much is this to get done

[RonnieRev]

When you buy the pipe get a jet kit to go with it,
Dyno-jet is probally the most popular

[markdh]

... but thats not a necessity right?

[meme]

depends on how much you have modified the air flow....

"Carburetors supply a mixture of gasoline and air to the engine. The gas comes out of little things called “jets” (usually a pilot jet, needle jet and main jet). If you modify your airbox or exhaust to flow more freely, you get more air going through your system. This often means that there is not enough gasoline, so the engine runs badly. “Rejetting” means replacing or modifying some of these jets so as to supply gasoline differently than stock, usually more gasoline than stock. If done correctly, this allows your engine to generate more power, run a little cooler, start and run smoother and get worse mileage."

from here http://www.timberwoof.com/motorcycle...intaining.html

[macrider]

After installing the exhaust try adjusting the air mixture screws first before getting a rejet kit.It may be fine the way itis, it all depends on the kind of exhaust you get. Here a good step by step on exhausts and adjusting and rejetting for Honda Shadows.
http://whytlash.powweb.com/

[RC-31]

Carbs measure fuel by a difference in vacuum, they are accurately calibrated based on this. It's not so much that the aftermarket intake and exhaust parts allow more air in (the amount is pretty small, actually) so much as it effects the depression in venturi of the carb. The increase in airflow will lean out the mixture, and the drop in depression will lean out the mixture even more.

Adjusting the air screw will effect only closed throttle to 1/4 throttle openings. You might be able to shim the stock needle to raise it, (like opening up the main for part throttle,) but the needle really only effects 1/4 to 3/4 throttle. The main jet is responsible for everything over 3/4 throttle.

You will have better results by playing with the float height, but unless you have a degree in carburetor tuning, you probably won't get it running 100%.

Find other owners who are running the exact same setup and find out what they did.

Playing with the air screw is the last thing you do on a setup that's already right on -- not the other way around.

[toastman]

depends on the bike, 750 Shadow ACE doesn't make enough of a difference
the 1100 Spirit it makes a big difference

some shadows have one carb, some have two
It makes a big difference in the amount of work

Post up year make model and I'll help as much as I can

Donald

I have a Honda Shadow... was thinking of doing a pipe change over the winter. Question I have is about jets. I've heard alot of people say that you dont need to have the jets redone, others say for sure you do.

1) do you really need to get the jets redone?

2) if you do, how much is this to get done

[markdh]

I have a 2007 VT 750 C2 (Shadow Spirit)

Nothing has been modified on the bike except for seat and sissy bar.

Just looking at new pipes (Vance & Hines) but wasnt sure if I needed to rejet or adjust carb, and if alot of work involved.

Not much of a mechanic... could put the pipes on myself, but wouldnt want to tackle carb modification/rejet/etc. Dont want to add different air intake kit or anything.

[toastman]

that bike hardly benefits from a jet kit, I'd go the route of pipes only.

Donald

[markdh]

But if I replace the pipes, do I need to take it to a mechanic to have them adjust the carb or something?

[Katapult]

that bike hardly benefits from a jet kit, I'd go the route of pipes only.

Donald

On my 2000 Shadow Ace i hollowed out the factory pipe. Until I jetted it, whenever I rolled off the throttle there was major backfiring. There was a pretty good light show out the tailpipe.

Install the pipes and see how it runs. Mine never ran right until I had Kneedragger work on the carbs.

[macrider]

Markdh, It is easy to adjust the carbs on your shadow, I have 2 shadows and when I went to Vance and Hines exhausts I adjusted mine. I posted a site above but perhaps the section you needed was hard to find, so here it is copied and pasted, its an easy step by step process.
hope this helps!

Adjusting The Mixture Screws

When making modifications to the stock exhaust such as punching or drilling holes, or after adding an aftermarket exhaust, it may become necessary to make some adjustments to the pilot jet (idle circuit) air mixture screws to eliminate the "Rice Krispies", the crackling and popping you get when decelerating. Here's how it's done.
Oh, and by the way, just for RockRabbit, the left side screw is for the rear cylinder (see the cylinder intake port and the boot from the left carb running down onto it?), and the right side screw is for the front cylinder (look at the intake boot, same as the left side.).
UPDATE! Please see the Exhaust Mods & Mixture Screw Update.
***If you have installed Stage 3 jetting and the larger Aero #42 slow jets, the factory 2 1/4 turns open is sufficient in most cases!***

Click on a thumbnail to enlarge.
To get rid of that nasty popping on decel, you have to have more fuel at idle. I originally just raised my idle with the idle screw (the black knob on the left side of your carb in front of the throttle wheel that you cable run to from the throttle on the handlebar), until I could figure out where the air mixture screw was.

On the left side of the carb where the throttle wheel is, right below it you will see a silver plug ( mine had a felt tip marker slash on it, that way they can tell if it's the original I guess) about 1/4" in diameter. Forward of it is a brass screw that is the drain screw for that carb. If you turn that screw counterclockwise to unscrew it, fuel will start dribbling out of the little nipple right below it.

SO DON'T DO THAT, I'M JUST POINTING IT OUT.

Anyway, I got a small drill bit, about 1/16" (I think), and carefully drilled a hole in the center of the plug. Don't push too hard or it will go through the plug and hit the screw behind it. Use just a little pressure. After drilling, get a sheet metal screw that has threads a little bigger than the hole you just drilled and start to screw it in the hole. When it gets tight, get a pair of pliers and grab hold of the screw (vice-grips would work good here) and carefully tug on the screw. Eventually the screw with the plug attached to it will pop out. Look into the hole the plug came out of.
There you will see the holy grail, the brass AIR MIXTURE SCREW!

Repeat the steps above on the right side carb. To get to the right side carb, you will have to remove the air box. The air box comes off easy. Use the allen wrench in your bike's toolkit to remove the six screws that hold the airbox cover on. Pull the filter out.

On the back side of the airbox on the front and rear, (looking down from the tank) you will see two bolts with allen sockets in them. Use the other allen in your kit to remove these, or a ratchet with a 10 mm socket. The heads are about 1/2". You can't miss them.
Then, look behind the airbox on the forward side near the top. There is a steel band that is tightened around the tube that leads from the airbox in the top of the carbs. Loosen the screw on the band. Now just pull the airbox toward you and down and out she'll come.






Now you can see the plug over the right side air mixture screw in the same place as on the left side.


According to the Honda Service Manual, the factory setting for these screws is 2 1/4 turns open. These screws adjust the amount of fuel that the pilot jets (idle jets) squirt into the carbs. Carefully screw each one in until it lightly seats closed, and count the number of turns. This will tell you the number of turns each was open and give you a new starting point for adjustment. Now carefully screw out (open) each one to 3 1/4 turns open (1 full turn beyond the factory setting).
If you're picky, like me, take each plug you removed and drill the hole just large enough for the tip of your little tiny screwdriver to get through, then reinsert the plugs. Or, you can stick a little dab of silicone sealant in each hole. It sets up, hold the screw, and comes out easy if you want to "fiddle" later on.
That's all there is to it! It's actually pretty simple, just need someone to tell you where stuff is. And pictures are always helpful.


Scans from the Service Manual covering the mixture screw adjustment.

[boyoboy]

hi, i would contact the exhaust system manufacturer. they should be able to provide you with technical information specifically for your application. you may, or may not, have to re jet the carbs. send em a note....

[boyoboy]

On my 2000 Shadow Ace i hollowed out the factory pipe. Until I jetted it, whenever I rolled off the throttle there was major backfiring. There was a pretty good light show out the tailpipe.

Install the pipes and see how it runs. Mine never ran right until I had Kneedragger work on the carbs.

jeeez.... that kneedragger guy keeps on properly fixing bikes .....always reading good things about the guy...

[Katapult]

macrider's advise is sound. I forgot that I changed my intake as well - i put a K&N filter in and couldn't get the adjustments correct with just the idle screws.

Kneedragger did a great job. He put the wrong jets in the first time around but after one phone call, i was back into his garage and he replaced them on the spot - great work.