Carb rejetting

I know that there are mixed thoughts on this subject, but I'm getting ready to tear down my carbs and clean/rebuild/rejet them. I searched the forum "briefly" and didn't see any info there. Since I'm running a MAC 4-into-1 header and air filter pods, what would be the best jet sizes to use for my Seca 550?

MY airbox was devoured by a family or two or rodents...that's why I'm switching to the pods.

 

Look in Chacal's catalog. He has a starting point formula for adding +/- jet sizes based on mods. They'll get you a start. You may still have to change several times.

Did you try running it with the jets in it? Sometimes you get lucky.

Also, if you need a hand with the carbs I'm in Baltimore and have helped guys out before.

 

The bike hasn't run since '04, so I can't honestly answer that question. I do remember that it ran fine (with the airbox) up to 7K RPMs. Then it would sputter and run erratically. That was traced back to faulty carb manifolds...of which I have 4 brand-spank-me new ones ready to go.

Is this Chacal's catalog something I can look for on the 'net?

Appreciate the offer...hopefully, I'll get them ironed-out. If I can't, a friend of mine is a self-appointed carb guru.

 

Go to the upper right corner of this page.
You should also search the topic of plug chops / plug reading.

 

You might want to consider putting-out an A-P-B for a used Airbox.

In the long-run, you will have considerably less experimental-type tuning and re-jetting to do, with the INTAKE regulated by a Stock Airbox.

A Web Search of Salvage Yards or Ebay might be very fruitful.

http://www.drumhillcycle.com/index.cfm/ ... /3,3879348

 

Wow...what a raft of information and specs. Does this "Chacal" walk on water, too? Amazing pages....thanks for the heads-up.

Here's my reasoning for sticking with the pods...for now, at least. A friend of mine owns a bike shop across the river from me in Wrightsville, PA. Their shop's being featured on Cafe Racer on HDTheatre. I had visions of doing a cafe resto-mod to my Seca for many years, and I'm thinking that NOW is the time to execute that plan. It's a timing thing. All of J&B Moto's bikes have pods and they swear that they have absolutely no problem with them or the carbs.

As Chacal states on one of his pages...
"Some people don't heed our well-intentioned advice..."

I'm one of those people, I guess! :roll:

 

pods or not it's your bike. You may get lucky and you may spend tons of time getting your jets setup. You won't know until you try it.

 

Yeah, you're right...it is my bike and I'm building it to suit my tastes. But I also live by the axiom of "Do it right the first time" - so that I don't have to do it a second time. Sometimes it pays off, sometimes it doesn't. I'd really rather not have to fight with wacko carbs all summer, but I know what I want my bike to look and run like. Therein lies my predicament. As it goes right now, I have a dream of circum-navigating Pennsylvania this summer. I also have a nightmare of wrenching on my bike after every ride to get those *(&%!^%$ carbs right! Maybe it's a good thing that I have 2 sets of carbs.

 

the easiest way to get it right the first time is to stick with what Yamaha decided it should have for intake, exhaust and jets.

But you've already got a 4-1 so the exhaust is different. And if you really want pods it can be done. How many times you'll need to change jets no one on this site can say for certain. It vaires with each bike. Once it's set up though it's good.

 

That's why Yamaha has engineers/mechanics in-house...to figure these things out.

Fortunately, I have 3 very reliable sources for carb work close by.

Since the factory exhaust committed suicide and mice ate through the airbox, I had to use aftermarket components. The airbox is the easiest (and cheapest) part to replace...the exhaust would be $$$$$$ to replace. The current economy dictates 'aftermarket' for me.

 

I'm not one to tell people to leave bikes stock. Mine's not stock by along shot. I had to change jets with my custom exhaust.

Just want to make sure you know what you might be in for.

And with 3 people able to help and this board you should be able to get it to run reliably with pods.

Some will say it won't be "fine" tuned because of CV carbs and the unlimited air flow. That's probably true. But there's plenty of guys on here who have reliable, rideable , bikes with pods. So it can be done.

Keep the stock jets, and if you get really frustrated with the pods, find an air box and go back to yahama's design.

 

MUCH much easier to retune for just an aftermarket exhaust than to start the "pod fight." Especially on a 550.

If you want to run a 4-1, that's fine; but if you want to end up with a reasonably trouble-free mount, stick to the stock airbox if at all possible.

 

Before you decide on how to set-up your Bike, ... you need to ask your racing Buddies, ... IF the Carbs on their Cafe' Racers are the SAME as the ones you have on your Bike.

 

Just read your post....

No, he does not walk on water, as he approaches it parts so his feet don't get wet! 8O
:twisted: :twisted: :twisted:

 

Finished the bike in the spring, rejetted/sync'd the carbs to account for the pod filters (a ONE time deal for the dial-in), and spent all summer riding without any problems or carb issues. It really wasn't a hassle at all...printed out Chacal's carb rejetting pages, handed them over to my tuning guru, and we spent an evening doing the final tune. The only issue I had was a float sticking on the one carb, which resulted in a minor leak. Took the bowl off, cleaned it out, and that solved it. Thanks to all who provided info and/or advice...and thanks to Chacal for the rejetting specs.

 

Can you provide a recent picture of the bike. I looked at your profile and seen a yellow and black combo. Wanted to see if you painted the tank or changed the paint job.

Thanks

 

Do you know the jet sizes you ended up using?