Bonneville America Forums Forums Technical Forums General Tech Air intake issue

I posted a few weeks ago about my 2003 BA I purchased. It cuts out (completely dying) on windy days at highway speeds, but doesn't seem to have a problem in town or when the wind direction is of a different orientation. The days with the most problems were when I was traveling south against a strong wind coming from the south.

I took the bike back to the place where I bought it (not a Triumph oriented place). The guys there have worked with me, but really don't seem to know too much about my BA. They called three Triumph dealerships and the consensus was to put the stock airbox back in.

The bike has a ton of aftermarket parts; most of which I know nothing about... Last time you guys asked about a ton of things I didn't even know how to check.

My question is:
Could the aftermarket intake (of the dual intake cone filter variety) be allowing the bike to run way too lean?

I'm in KS, by the way.

It is possible... I'd go through the carbs and figure out what the jetting situation is. Check your hose clamps insuring there is no vacuum leaks. Check the squirrel condoms too (black rubber nipples) could be cracked or whatnot. I think that is a good start. Also make sure there is a carb brace in place somewhere since the airbox has been removed. I guess just make sure the hose clamp isn't the only thing holding your carbs and filters up.

I had the same problem...youre running too lean. Its not the airfilters fault you just need to bump up your gas intake with bigger jets.

I'll try an find all of those things. The bike's at the shop now; I'll have to make a run.

How do I know how big of jets to get?
Cost?

Also, go take a gander at the tech vault. Lots of very informative stuff. You're going to need the jetting calculator in that link to find the correct jets for your setup.

Where you at in Kansas? If we're close, I'd be more than happy to lend a hand.

Emporia.

100 miles from KC down I-35.

Jetting Calculator a no-go.

I only know the elevation and am using an educated guess on the air filtration. Don't even know how to check the other figures.

If the bike is running too lean, wouldn't putting a more restrictive air box on fix the issue?

I know it's counter-productive, but at least I could ride it. Plus, I could get it to KC where there's more resources.

Cory, I was in the same spot youre in a couple years ago. Believe it or not it'd take more hassle to put an airbox back in then just rejetting the thing. I'm assuming you bought the bike used and have no clue whats been done? Same with me when I first came to this site.

What cochran listed is important to check as well. I actually went through everything on my bike that was suggested to me with no luck and finally came to the conclusion that my mains were only a size smaller.

This link taught me everything I need to know
http://www.dinqua.com/Triumph/carbs1.html

once you go through the process it becomes alot faster. Theres a bit of trial and error here as well. Its not an exact science. I got to the point were changing jets were as routine as changing the spark plugs.

You need to find out what main jets are in the carbs right now. Theres numbers stamped on the jets. I'm no expert but I assume youre right on the line between lean and fine due to the slight flucuations with the wind/speed.

Its possible that the guy before you was affraid to mess the carbs when he removed the airbox and youre at stock jetting. You could possibly only need to bump up your main jet one size. But its always good to get a couple sizes just in case. Its also important to only change one thing at a time in order to properly diagnose the situation.

If your jet says 140 try a 145, if you notice it still got to a 150....etc.

Would I need to replace the pilot jets if I replace the main jets?

I'm looking at Keihin Jets from newspeedmaster.

It depends on your situation. In a nutshell..

Pilot jets handle low speeds
Main jets handle higher speeds

your problem was at higher speeds so a good starting point would be to change the mains first.

I figure youre trying to make one order from newspeedmaster and get everything you need right off the bat to keep the waiting down. Its a pain, but take your carbs apart before you order so you know what your working with.

Theres no hurt in getting a couple mains, the next bigger pilot. and DEFINATELY allen carb screw kit.

Take a look at the screws on the top of your carb. If theyre the stock screws they'll be phillips. You'll want to replace them with the allen screw kit when youre doing the rejet. The stock screws will strip right away and you'll have some major problems at that point.

You can find the same screws at an ace hardware put make sure theyre the same length and Stainless steel.

To change the mains I only have to take off the bowls, correct?

Can you recommend an allen screw kit that includes all I will need?

What about just putting some shims in? Doesn't that allow more fuel as well?

Sorry guys, I'm pretty slow with this. I am learning a ton though, thank you.

Yes, you just have to drop the bowls to install mains, but better to pull carbs first if you have stock screws, as you will strip one or more if you're not real careful/ lucky!
Needle shims address a mid-throttle bog...
and... your screw kit. (just one option) http://newspeedmaster.com/html/carb_screw_kit.html

If its one thing Ive learned its "take everyting apart". At least on your first time, its important to take the carbs apart like it says in the dinqua link I gave you.

Yes you can just take off the bowls but it'll be very hard to verify locations of certain things and you'll spend more time working around things and fumbling around. Take the carbs off the engine and leave the cables still hooked up just like dinqua has in the link. Its worth it to see exactly what youre loosing/tightening and take your time.

I assume youre hesitant, you dont wanna break anything and youre not looking to take everything apart. I understand completely. I was in the same boat 3 years ago. I never touched a carb or even worked on a motorcycle until I read that Dinqua link and learned from this site how to do things.

The allen screw kit on newspeedmaster.com

Yes shims add more fuel but at a smaller increment and if I remember correctly more on the higher throttle end. Thats more on the tweeking side of things.

If youre cutting out completely (did you mean engine dying?) then you need to add more fuel at the "main" source.

****** Rob I gotta stop typing paragraphs while youre sneekin in there with the same info...haha

ya gotta love this site...theres people racing against each other to type the same information...oops there I go rambling paragraphs again...haha

Not racing... just bored at work today!

yes sir 15 minutes to go for me....3 cheers for computer jobs!

OK, Goofy Time!
You said originally that this happened at freeway speeds on windy days.
Have you checked the vent tubes hanging down below the bike?
Sometimes the wind can catch the opening of these babies just
right, and mess up your day.
If they are hanging down kinda far, see if moving them helps.
If it doesn't work, fine, but if it does it's the easiest
fix you'll ever do.

This site is awesome...

Thanks for all of the replies. I'm not going to touch it until the shop I bought it from gives it back. I talked to them and they are working with some Triumph dealerships to fix the problem. I'm assuming they are covering the issue since the bike is so new to me.

I think it's best to let them deal with it; at least until they say they won't stand behind it.

The shop is also trying to contact the previous owner to see if he has the stock air box; which is what they want to put back on. Fine by me, for now. Besides, I'll still have the aftermarket one to reinstall if I want.

According to the guy at the shop, the jets were upgraded when the rest of the bike was done. There's a crap-load of accessories and add-ons on the bike.

I want to get comfortable riding it before I go too gonzo on additional accessories.

Thanks for all the replies. I'm still very hesitant about tearing into a bike I haven't even made the first payment on yet. I'm sure it won't be long before I'm digging in.

The links are awesome.

There is a good chance you will need a larger main. I would guess you have less restrictive exhaust on there too if the last owner took the trouble to remove the air box. If you could give an idea what you have for exhaust we could give you a better idea what the main should be. Without that info any guess is just that, a guess.

Large and loud exhaust. It looks a lot like the Sceptre long pipes. I can't find a brand mark anywhere on it. It doesn't sound like any Triumph I've ever heard in person or on the internet.

If there are no baffles in there and you have the pods you will probably be up around a 150 main give or take and a 45 pilot. That is an educated guess from what you have told me. Your exact location could effect that one way or another a little.

I've been kinda lurking around this thread as it developed. There was that thread I started about me pulling the snorkel and everyone suggesting I rejet. Well I jammed out and just put the snorkel back in but ya know, from reading this thread I think I might just build up the confidence to pull those carbs and beef 'er up. I'm handy, but I just have no experience with carbs and stuff. Should what... consume a weekend while I get familiarized with the workings of the carbs AND get the job done?

Well, if you use that excuse (that I never did it before),how did you get pass first base?

why is it that when something is untoward, the techs blindly say, "take out it back to stock"? grrr

Until you index your setup we all spit in the wind.
index meaning knowing and reporting how your carbs are currently setup, i.e., mains, pilots, jet needles, jet needles shims, air mixture screw turn-outs.

what kind of brewskis you dole out for guest, what brand of papers...

you'll get it sorted.

I was just trying to point out that the first time your carbs were off and apart you had help to show you where things were and how they came apart and went back together. That isn't indespensable but it does help the first time

Yeah it is indespensible, its ashame I cant learn more off of you.

Here's my suggestion. When does your bike come home, Cory? I'd say you post a few pics of the pipes (including inside so we can see baffles) and some shots of the air intake set up. Which sounds like is heading back to stock...God help us

You're basic set up right now is:

K&N pod filters
Carb jets unknown
Air Fuel mixture screw unknown
Some sort of sceptre, bub, trident, etc exhaust
Sea level elevation
Shims and needles unknown

I'd say it's most important to pull the carbs as suggested and find the size of those jets. If you have shims and what kind of needles. You'd be surprised how many of these guys can recognize a part or specific brand by a picture. We love pics Then we can fill in some of those unknowns and get better suggestions to you. And while your at it might as well move those vent tubes around like Brian said...can't hurt!

Not sure when I get it back. Whenever they find a stock box to put on. I think the issue has a lot to do with the main jet. That makes sense to me.

I'm still going to let the shop do whatever; as long as I get all the parts back and a running machine the rest can be addressed later.

Now, I'm very curious to see what's in those carbs as well. Almost obsessively....

When I get it back, I'm going to ride it until I'm pretty sure I can't walk. After that a cleaning, then pictures.

Why would three Triumph dealerships say the same thing as far as the "issue"?

There are more bikes running around with no air box or modded air box than a stock one. not saying a stock air box won't work but for the shop that's the easy way out requiring the least effort (mental effort)on their part. Stock box, stock jets, no thinking involved.