Bonneville America Forums Forums Technical Forums General Tech General performance questions

Howdy Folks,
I just got a '03 BA stock pipes and air. It's been cold here so I've only had it out a few times. I'm used to riding my '70 Sportster so my first impression of the BA was that it was like riding an easy chair. Handles great and the brakes work. Now a few rides into it I'm noticing some quirks. I still make it "chatter" or "gargle" when I start to move. I'm having a hard time finding that correct balance of clutch and throttle. I'm tending to give a lot of gas and take off quick to avoid the chattering. Now I notice the throttle is a bit slow. Revving in the driveway there is a slight hesitation. Riding down the road I'll slow down a bit, give the gas again and it "stutters" or bogs a little before "coming back" and gaining speed. Questions are,
Is this normal and this is what all the carb/airbox mods I read about here are for?
Its just routine maintainence like old plugs and fuel filter? {11,500 miles on bike}
Or its just me being clumsy getting to know the new bike, like I gotta learn what RPM to shift at and whatnot. The bike is so quiet I can't tell what the motor is doing. Again, I'm used to a 4-speed antique.
Thanks, any ideas appreciated.

Wow! You survived a 70 sporty! Conratulations! It could be that you're more used to the torgue of an inline twin. Shifting too soon, clutching too hard. Still, with only that many miles on it, I wonder if the "hidden" filter doesn't need looked at. Did it sit for a long time? Maybe gummed up a little?

If it's quiet, it has the wrong pipes. A nice pair of Epco Stainless or Thunderbike mufflers and a jet change will do wonders, especially if you pop out all the bits of rubber tubing you find in the air box. Some have 3, some only have the one at the inlet. Also, the idle mixture adjustment is critical since the idle and transition ports come back online at hight speed acting as a power enrichment circuit. Adjust for best idle speed and you should be alright. Richening the idle mix enough to stop the pipes from popping on deceleration will cost you some 5 to 10 MPH of topend. With these mods, my '03 would run off from the OL's 88 inch Lowrider and the 96 inch Roadking she traded it in on.
If you still have the air injection system (silver tubes next to the sparkplugs) installed, go to newbonneville.com and get the removal kit. It won't do anything to the performance, but it will make the pipes run cooler (less discoloration) and maybe extend the exhaust valve life.

Not knowing the service history of the bike, it is hard to respond to your question.
Without jumping into any mods right away, I'd put fresh plugs in it, a new air filter, run some Seafoam thru the fuel system, and check the adjustment of the throttle cables. Check your idle speed - the black knob under the left carb - as turning it up a hair may improve your initial throttle response. Synchronize your carbs. You may also want to check the condition of the rubber parts - the hoses between the airbox and the carbs and the carbs and the manifolds. Snug up the clamps on all. Check the squirrel condoms too - the 4 rubber "caps" over the manifold ports and carb ports. Check the exhaust conections as well. The nuts holding the headers, the header to silencer connections and the crossover connection underneath. Look for carbon tracks. Any loose connection on the exhaust will suck air and upset the mixture.

Bear in mind that these are higher revving engines with a limiter around 7300 rpm. Once you get the stutter out of the way, you can look into the mods (one at a time) to reach nirvana. Pipes, jets, drilling the slides, removing the snorkels, drilling the filter/airbox, pod filters/freak, sprocket changes, etc....

The Tech Vault has a ton of info on all these things....

BTW, my mother grew up in Bucks County - went to Bensalem (?) high school. That would be about 70 years ago....

On the 03 you may want to drill your slides to help get rid of the throttle hesitation and the airbox and exhaust mods do help with the things you mention. This being said I would like stated above do all the standard maintenance first and check to be sure you don't have any vacume leaks and the fuel filter is clean. The chatter shouldn't be there in the clutch. My clutch and Wendys for that matter are very smooth. Be sure you have the right kind of oil in there and enough of it. You may have hardened spots on the clutch plates and some warpage due to an inexperienced rider slipping it too much, could also be extremely uneven spring tension. If you decide to pull the cover and check be sure you buy a new gasket as I hear that one is not reusable.

Thanks guys, I'll take a poke at it this afternoon. And man-o-man talk about a hidden fuel filter, I don't see a thing. I guess the tank has to come off to reach those little hoses?
I'm taking my time with the exaust mods. I just missed a set of pipes on ebay last night. There's so much to read about pipes here its downright confusing. Same with all the different ways to deal with the airbox. I'll start with whats ever cheap and easy.
What is "drill the slides"

There is a passage in the slide in the carb that allows vacume to get above the diaphram slide. The older bikes had a smaller passage so it took slightly longer to get the vacume up there to lift the slide. Drilling fixes that and on later bikes it already is the larger size. You can cut the springs for faster response too but thats not for a novice.

>man-o-man talk about a hidden fuel filter

Yeah, a real pita.
It sits in the T between the carbs.
Maybe why Deon suggested seafoam & balance for starters.

Drilling the slides refers to enlargement of the air passage in them for quicker (vacuum operated) slide response.

Maybe it's not warmed up enough. ride a couple of blocks with the choke on.

Drilling the slides, courtesy of Triumphant - who may or may not be a member here any more....

Drilling the slides

Thanks again guys, learning more all the time. I checked my book and it says my plugs are due for replacment, so that may be part of slow throttle issue. Easy enough, but now I'm looking and I appears you can't get the plugs out with out removing the tank. Haha, I can change em' when I'm doing the fuel filter. My old ironhead you can reach all this stuff easy.

Why remove the tank? A ratchet with a 3 inch extension and a sparkplug socket should do the trick.

Snicker, snicker... It's started.... the pursuit of happiness...