Bonneville America Forums Forums Technical Forums General Tech Air mixture problem, perhaps?

Hello,

A year ago, I bought my 03 BA. It had a lot of acc's and performance parts added.

It came to me with Sceptre pipes and a K&N Freak intake.

When riding on windy days, the bike would struggle to get fuel and would die. I took the bike back to the shop I bought it from and tried a few different things until we switched back to the stock air box.

This fixed things as far as riding in windy weather, but I don't think things are "right".

-I only get a little over 30 MPH, ever.
-I have K155 mains (figured out how to take the bowls off!) Presumably, from when the intake and pipes were installed. I was told it had been rejetted.
-When I had the bowls off, I noticed the mixture screws still had the cover on.
-I pulled the snorkel to give it more air as I believe it's been running rich (MPG, soot in exhaust). Going against a 30 MPH headwind with greater gusts, with the snorkel out, the bike bogs down during the worst gusts. Put the snorkel in, no bog.

I am thinking the jets were replaced with the intake and exhaust, but the mixture screw was left at the stock setting. Would this make sense?

Also, how does one go about drilling the cap? Is there another way? Possibly, where I can get to the
mixture screws with jusst taking the bowls off?

This leads me to believe I may be able to put the K&N intake back on and adjust the mixture screws to make it work. 155 mains seems very big for using the stock box (according to the Dinqua jetting calculator).

I can't see how riding in windy weather would affect the fuel delivery system unless (and this is a long shot) it might affect the vent tube behind the engine. Might be syphoning and causing a vacuum in the tank restricting fuel delivery. Did you ever try loosening the fuel cap when it was happening to rule out the vent problem? Try cutting the vent hose outlet behind the engine at a 45% angle instead of the typical 90% it is cut to.

155 mains are waaaaayy too large for the stock intake/airbox. Might even be a tad too large for the Freak. You also have to open up the idle mixture adjustment screws. That should have been done first. I didn't think that the early Americas came with a plug over the idle screws???

Drill the cap with a small bit then insert a screw and pull the plug with pliers. You might have to remove the carbs.

It has an aftermarket kuryakyn fuel cap. I believe this would relieve any venting issues.

According to the calculator, 155 is what would go on my bike with the FREAK.

I'll recheck the plug covers...

Well, the plug is definitely still there:

You said you went back to stock air box and in that case the 155 would be way too big, Open Scepter pipes and K&N pods the 155 would be in the ball park depending where you live. The pilots should be 45 to 48 but the mixture screws need to be adjusted too.

The EPA caps can be removed with the carbs in place but will only affect the idle. I assume you mean that you only get 30 mpg not 30 mph. I'd make sure that the vent line is not partially blocked, in case your aftermarket cap isn't vented,(although I'm sure it is). If it begins to die out, just loosen the cap slightly to eliminate any possability of a venting issue.
Always keep it simple; make sure someone didn't put the wrong plugs in or something else which might be overlooked.I know that you think it's running rich. What do the plugs look like? There's a tiny fuel filter (screen in the metal tube flowing to the carbs) which can only be accessed when the rubber fuel line is removed at the carb end. I have seen these screens load up with rust when condensation builds up in the tank; my screen is removed. Look for the obvious and you'll rarely be dissapointed. Mostly, be methodical, start at the beginning.
Good luck

Quote:

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I didn't think that the early Americas came with a plug over the idle screws

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Huh. Mine's an '03 and there no plug on the idle screws.

My 04 didn't have the plugs and neither did Wendy's. Bought ours used but unaltered, they may have been removed already. Mine had 700 miles on it and Wendy's 1500 miles. Mine had TORs on it when I bought it but stock otherwise, hers just had a couple bolt on parts like windshield.

That plug in your picture does not look stock.
Maybe someone else can chime in on this but isn't the OEM plug a sort of mini freeze plug looking thing? That one looks solid with a small hole in it (maybe to make removal easier).

Ah!

Just remember, the Jet calculator is a guide and not gospel. Every bike has it's own idiosyncrasies so setting and forgetting from the calculator wouldn't be the best way to go.

It is also fairly well understood that Pat's calculator errs on the side of caution regarding ensuring he hasn't recommended jets which would possibly lead to a lean condition. It wouldn't be worth his trouble in the first place to have irate members emailing him and saying "But your calculator said I should use jet number blah blah blah" and now I've damaged my valves".

Nah, Pat isn't a dummy but at the same time he's offered this site (and our community) a lot of valuable info. I wouldn't have thought he'd intend having it come back and bight him though.

One final thing, Pat has had to rely on results from others to formulate the calculator. I mean, I wouldn't have thought he'd personally tried every variation of pipes and air boxes

In saying all this though, the calculator for newbies is a fantastic tool and a great starting point until members learn a bit more themselves and start tweaking the "general guide" calculator.

If Pat or anyone else disagrees, that's fine too. I been wrong before once or twice like all of us but I'm pretty certain I'm on the right track here. VB