Bonneville America Forums Forums Technical Forums General Tech Intermittent poor running (carb - fuel/air issue?)

I will unfortunately have to make this a bit lengthy to pass all pertinent information...

I am now $420 in the hole trying to fix a problem with my 08 America. From time to time, the bike runs like crap, like it is either starved for gas or is way too rich. I have to rev way up to start out to avoid stalling, can't shift beyond 4th gear without stalling even at 55 mph. Smells of gas when running and the MPG goes from approx 45 to 30-35. Further, I am beginning to get discoloration at the pipes due to this.

Have had it since May of 2011, bought used from a Triumph dealer and before taking had the TOR long pipes put on it to replace the stock pipes. I asked the dealer to adjust the carbs for the pipes, they did not tell me what they did to set it up. It ran perfect from May until some time in late November for about a 1000 miles before I first had the issue.

Taken it to two shops already, the first, a Triumph dealer (not the one it was bought from) cleaned the carbs, adjusted fuel/air mix and replaced the fouled plugs ($300). They never gave me a straight answer regarding what caused the problem. Did note that it now has a 42 pilot jet and told me that a 40 is stock. They suggested a jet kit but did not indicate that the lack of a jet kit was the problem with it running poorly.

Following this, it ran fine for about 4 days and began the intermittent issue again. I then tried smaller shop and they tightened the intake clamp and adjusted the fuel/air mixture ($120). The mechanic mentioned that the air injection tubes were capped. Apparently this is a common modification made to help the bike run better? Anyway, he did not suggest changing it.

Well, it ran fine for about 5 days until today and I had the issue again!

No rhyme or reason to when it happens, cold, hot, after it has ran for a bit, right at startup, it will sometimes resume running well after having the problem at startup, etc. No patterns at all. Further, it either runs 100% fine or has the issue, no in between. When I am going down the road while it is running bad and it reverts to running ok, it occurs in a split second and will generally run fine until I shut down. After setting, it may run fine or it may have the issue again at startup.

Wondering if anybody has had a similar issue with a carbureted twin Triumph (02-08)? Any suggestions are welcome. I will contact the second shop tomorrow. The most frustrating thing is that it only occurs intermittent so perhaps the mechanics have not experienced it run like crap. It is miserable to ride and I am causing the pipes to discolor so WANT IT FIXED!

What are you running for intake? Stock air box or pod filters?
Do you know if the bike has any of the Ca emissions canisters on it (they are located under the bike at the rear, between the frame rails, just before the rear tire)?

Don't know for certain but believe it has a stock air box (I certainly have not changed it) and I don't believe this would have the California emission crap, I don't see any canisters by the back wheel and it was purchased new in either Minnesota or Wisconsin.

I would start at the tank and clean and inspect everything down to the carbs. Take the petcock out, check the hidden filter,etc...

Can you tell us what the bike runs like when it is bad....ie. does it feel like it is running on 1 cylinder (missing) or is it just running rough? If running on 1 cylinder, can you tell which one? Since the condition seems to come and go at will and it is an instant change, I'd guess that the problem is electrical. If it is running on one cylinder at times, you will get a smell of gas.

Since the bike ran well from May to November, the carb setup is probably not the main issue. I wouldn't play with pilot or main jets until you have solved the poor running issue.

About the plugs, you stated that the dealer changed them because they were fouled. Were both black or only one?

I would make sure that the 2 primary wires going to each coil are tight. I would also make sure that the spark plug wires from the coils are also right in the coils and tight.

If the bike appears to only run rough and not miss, you could have a sticking needle valve (attached to the float) causing the carb to flood. If this is happening, you could have fuel pouring out of the carb at the vent or into your engine. Is the engine oil contaminated with gas? This condition usually doesn't come and go instantly though. If the needle valve is sticking closed, you would get a lean condition, stuck open a rich condition. I doubt both needle valves (one in each carb) would stick at the same time though. It wouldn't hurt to try some Seafoam additive to devarnish/clean the carbs.

I think both cylinders are firing at all times, no missing noticed, both pipes are beginning to turn yellow, exhaust output is equal from both pipes when it acts up. I don't recall the dealer mentioning one plug only being fouled.

When acting up it idles fine, I don't notice the issue until I try to take off and it stalls or I have to rev way up to prevent stalling.

It seems like there is something either plugging it up or a vacuum leak causing too much air. Still leaning towards a fuel/air problem. Thanks.

I had a Mustang that had similar problems, to make a long story short, the factory ID tag that had the part number of the fuel level sending unit, ended up floating around the tank and would wrap its self around the fuel pick-up screen and choke the fuel off shutting the engine down. Let it sit for awhile it would float away until it ran for awhile and wrap its self around again. Your results might be different.

Check your air box for cracks around the area the carbs attach to the box.
While your there check the carb vacuum caps. They should be snug and not cracking.
Sounds like the carbs may have been removed at least once. Spray some carb cleaner around the intake manifolds at the head to check for a possible pinched rubber O ring.

I asked about the Ca emission stuff cause even though I bought two bikes form the same dealer here in Wa one had Ca emissions installed. It was a problem on that bike until I removed it all.

Because of reading this

Quote:

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...When acting up it idles fine, I don't notice the issue until I try to take off and it stalls or I have to rev way up to prevent stalling...

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it sounds an awful lot like one of your coils is starting to fail.

sounds very much like an electrical issue to me as well.

Still at a loss to determine if it is lean or rich? When it is idling fine but has no power when reving up did you try pulling the enrichener (choke) to see if that helped or made things worse?

When do you notice the fuel smell?

Any one of the suggestions the fellows have stated could be the culprit.

Have you pulled the seat off to see if something isnt stuck inside the filter/air box? Piece of paper, dead mouse, etc etc. You might want to pull the filter and check inside the air box also.

All,

Thanks for the input. IF, I am able to determine the issue I will post for everyone's benefit.

Do you have a GILL or Procom CDI?

Sorry, I am far from a gearhead! Don't know what either of those things are but if they are not stock I am guessing not.

Gill is the stock CDI and Procom is an after market one.

as to rich or lean, I suspect rich due to gas smell, reduced MPG and I have tried pulling the choke out and this makes it worse. I only hedge on this because one of the mechanics said the pipes usually begin discoloring due to it running lean.

The CDI unit is another name for the electronic control module which controls the spark at the plugs.

You haven't washed the bike lately? The reason I'm asking, because I had a problem several years ago after I pressure washed my bike. I water logged my Throttle Position Sensor (attached to the side of the carb). I had some intermittant problems with driveability and power especially in the mid range which would come and go. My TPS was full of water. I fixed the problem by disconnecting the Throttle Position Sensor.

It can't hurt to try that. Take the wire coming from the sensor on the right carb. Follow it between the carbs and disconnect it at the connector (It is a tricky item to disconnect). Run the bike like that for a couple of days and let us know how it runs.

BTW - mines been disconnected for several years now with no issues.

I see most of the usual culprits have been covered here but just for kicks have you checked the tank vent line and the vacuum caps on the carbs? A cracked vacuum cap can contribute to a lean, backfiring condition while a clogged tank vent can restrict fuel flow, again leading to a lean situation. That fuel smell might simply be the idle air adjustment too many turns out and could be distracting you from the real culprit.

http://www.bonnevilleamerica.com/forums/...e=12#Post530160

Does this sound like your issue, at all?

Still suffering through this but made a discovery - when the bike is running poorly it is due to the right cylinder not firing. I pulled each plug wire to confirm this. What I need to determine is why the right side is failing. I think it is a fuel issue and is fouling. Lately the bike will run poorly on cold startup (not always though) and rectifies after a few miles and does not revert back until shut off and allowed to cool. I wonder if perhaps fuel is flooding the carb while sitting and fouls the plug until the engine warms up enough to clear it and get the plug firing again? I am testing by shutting the fuel off when I let the bike sit for any period of time beyond a few minutes.

Any further ideas??

I'm guessing the problem is electrical. In order to determine if it is a coil or the CDI unit, swap the coil wires. Pull the 2 primary wires and large plug wire from the left coil and place them on the right one. Do the same for the right side placing them on the left. If the problem switches from the right cylinder to the left cylinder, the coil is bad. If the problem stays on the right cylinder, the CDI unit is bad.

I'm thinking coil, based on experience with my bike.

Thanks for the input. Since I have been shutting off the fuel when parked it has not repeated the problem. This does not mean it may not still appear as it has been intermittent all along. When it does repeat I plan to pull the right plug wire and check for a spark. Will go from there.

So the bike acted up this morning when I had time to work on it. Confirmed that the right cylinder was not functional. Confirmed no spark on right side. Switched coil and plug wires and right side continued to not fire. So the right coil did function when switching wires, which based on previous input would indicate the CDI unit, correct?

Can I order a new CDI unit online? And if I search CDI unit for 2008 America will one pull up or does it possibly go by another name? Thanks for the help, with this being an once in a while problem it was very helpful to receive the advice so I could diagnose myself.

Searched around and called a dealer, probably no news to anybody but me but the OEM CDI is $630. Terrible.

Found the Procom option as well:

http://www.procomeng.com/index.php?v...9&model_id=124

I think I might take my chances with this one. I did find a sight that offerred a one year warranty:

http://www.electrosport.com/hi-perfo...-t1292370.html

Well it is a relief to have the problem identified. Just wish it would have been a $50 component!

It appears you tracked down the problem. The Procom CDI unit can be purchased from Fast Eddy . A lot of fellows have purchased them.

Hope things work out for you.

I'd try to locate someone close to you who is willing to have a beer with you while you swap and try theres out on it.

Jacksonville, FL. Come on down!

Swapping out the CDI is pretty easy. Should take about 10-15 minutes. Just take your tank off, remove the old CDI and put the new one on.

Other than the Triumph factory CDI, the Procom is our only other option.

My in-laws live in Orange Park. Next time I'm down there I might have to look you up.

Let us know if it returns.