Bonneville America Forums Forums Technical Forums General Tech Cutting out issue

Hi, I'm new here..an Englishman living in USA, much like my new bike :-)

I recently bought a 2003 Bonneville America that had a 904 Big Bore kit. The bike had not been riden much in the last 2 years(<900 miles) but had a major service in 2010 according to the dealer at 48,000.

For the first few weeks riding I had no trouble at all but recently it has started to cut out momentarily or cut out completely forcing a restart. It seems to do this more when I'm accelrating hard and more often when turning left, although I'm not convinced its always left turns that trigger it. It did it at highway speeds last week when my son was riding it and today at low speeds for me too.

I've been running regular gas in it as per my dealers recommendations and also put some Seafoam gas cleaner in when i filled up last to see if it that helped.

I've read somewhere that the Big Bore Kit requires the use of Premium Gas but I'm not sure why or if I should ignore this advice as per my dealers advice. He was very specific about not useing Premium especially here in the NW(Oregon)

Can anyone offer any advice as to how to cure this or is it best to get my dealer to diagnose?

cheers for anyh advice

Rob

I don't think the grade of gas you are using will cause the cutting out problem you are stating. The 904 does use higher compression pistons, (depending on the kit) anywhere from 10.5 to 1 up to 12 to 1. I would recommend using premium gas especially with the higher compression kit. Do you know what kit was installed?

If the bike is cutting out when accelerating hard, you might be hitting the rev limiter which will shut the bike down, sometimes completely - do you have a tach?. My 03 America would cut out at an indicated 7200 rpm. I fixed this by getting the rev limiter raised to 8500. Another fix for me was to disconnect the throttle position sensor (right hand carb). Don't remove the sensor, simply disconnect it (bugger to unplug though).

Another item that has caused cutting out problems is a weak side stand spring which could cause the sidestand to come down while running (left hand turns?) which will cut out the engine.

Any more details on what actually happens? Cuts out suddenly, any sputtering, runs on one cylinder for a while?

Oh, and welcome to the forums Rob.

likely its the coils. They are breaking up and starting to fail when they get warm.
the difference between regular and premium gas is additives that make it less likely to pre-ignite, they slow the burn down. I use just some marvel mystery oil in my gas

so i just rode it home from work, the bike had been sitting in the sunshine so was warm. It was fine until I went around a circle so a left turn, it then coughed/cut out briefly when I accelerated away, then after that it continued to do the same thing when I accelerated, if I kept the revs low and pottered along it seemed to be fine, it seems to cut out when I give it gas quickly although towards the end of the 10 mile journey it was not cutting out even when I accelerated hard

floats in the carbs could be set too low. not enough gas in the bowl would cause some weird stuff like that. Partially clogged up main jetts could cause you to lean out at higher throttle.
How does it do just sitting if you rev here up? If you can borrow a timing light you can see if the light starts to fail at higher revs. If the light strobes strong while its coughing its fuel, If the light gives up (fails to strobe) while coughing its fire.

update: I found the fault. It was either a loose or dirty 30A fuse.

I took out both 30A fuses, one of them looked dirty on the connectors so I cleaned it off and reseated both. The problem has completely gone away

cheers for all the tips

Glad you found the problem...

It appears we lost a few responses to this post...

back to the drawing board :-(

it started cutting out again and worse now, I can drive for a while without problem and then when it cuts out it gets progessively worse. Things that happened today.....

Drove about 5 miles without problem from cold start, kept speed around 40-50mph, I then accelerated to 65mph quickly, and no soon had I done this and backed off a bit that it started to die. It then continued to die multiple times for the last 5 miles of my commute. I pulled over, cut the engine, waited 5 seconds, restarted with choke out for a fwe seconds and then pushed choke back in and rode last mile without any problems.

when it cuts out the Revs drop indicating that I've switched it off, but often it just fires back up without me doing anything. Sometime I have to pull the clutch in and restart while I'm rolling as it wont fire back up.

Any further ideas I can look at easily

It really is starting to sound like a coil going south. However, rework your electrical connections. And the very first one to check is the battery. Big time. Then unplug then replug, using dialectric grease, your coil connections. When this issue arises for you can you discern if both cylinders are firing? Hum, rather can you discern if both cylinders are not firing or is at least one? If only one side is firing, then that may be indicative of a failing cdi. Procedures exist for determining if indeed it is the cdi. However we may be jumping the gun about your problem. Another far reach would be the pickup-coil taking a crap. A post exist regarding testing the pickup-coil while it remains in place. Search for it if need be. If'n you can't find it we'll try to locate it and once we do, we'll place it in the tech vault.

I can't reiterate the need to check your battery connections enough. The positive side seems to loosen up over time and having a loose connection will cause your ride to exhibit the very symptoms you have described.

When one of my coils went bad, the symptoms, again, sounded like yours. The dern thing would work fine until I got around 5 miles. The bike would shut down for no reason. Then after a good warm up say 30 miles or so, the bike would stumble real bad off idle.

To trouble shoot a coil, you'll have to secure a loaner coil from someone. If you want to go the route of trying a different ignition coil, and can't find a member close to you to loan you one, let me know and I'll send you a known good coil to try out.

When it cuts out nothing is firing, the rev counter just drops to nothing and then sometime bounces back to where it was.

if 1 coil were failing would the bike cut out completely, aren't there 2 coils?

I'll check the battery tonight, I did take the battery cover off recently when poking around and it seemed tight but I only wiggled it with my fingers to see if it moved.

Sounds very much like battery connection (also check the main earth connection where it connects on the motor) or possibly the ignition switch (keys swtch) which has been known to cause intermittent failure.

This Post had a similar problem. The fix was the ignition switch. Note the corrosion on the switch contacts. The back of the switch can be removed and the contacts serviced.

You haven't driven in any heavy rain lately or pressure washed the bike recently? Cut-out symptoms sound similar to when you hit the rev limiter.

I've not driven in the rain at all or washed yet but I'll check the battery and ignition switch later

thanks for the tips

so it looks like it was the negative battery terminal being slightly loose.

It was odd as 2 days in a row riding in early to work the problem was very apparent, then riding home after the bike had sat in 90 degree heat all day the problem went away completely. I am guessing the warm weather during the day had expanded the metal on the connector slightly to keep it tight enough to not cause a problem on the ride home but when it was cold in the morning the connctors were loose.

thanks for all the advice

Rob

That's what makes this forum great! Glad you got it solved.

I did a handle bar change, put it back together and started riding..for a about a month or so the bike would stop running when turning left. I figured it must be a handle bar switch because that was what I changed out...so off comes the tank, pull the handlebars checked all connections and so on and so on...put the bike back together and just before I put the seat on I thought why not tighten the battery connection...well I never tighten the ground connection from the first time I did the bar change....so my lesson learned was to all ways start with the most simple things and then work from there.....

Coils going bad is what it sounds like to me.