Bonneville America Forums Forums Technical Forums Performance Mods HELP, PLUGS FOULING!

Here's my story and I'm stickin to it!
03 America
19,000 miles
Freak kit,158 mains,42 pilots,drilled vaccum ports(7/64)
Stock needles ,no shims.
Knurled(sp)Thumb idle mix screws from Bellacorse.(3turns out)I have tried 1.5,2,2.5,3,3.5,4 turns.
Stock pipes,two plates removed,4 holes drilled in next plate. Bike starts easy,idles good,runs good.
1000 ft above sealevel.
I have been running the set up (for the most part)for about 12000 miles,no problems.
All the sudden she's fouling plugs about every 200 miles.(Black sooty) Itried the iridium plugs,same issue.
Use only branded gas,exxon,Shell,Bp
Ok your thinking what's this guy changed he's not telling us about.

Changes I have made in the last 3-4 months.
Added the Thumb idle mix screws,drilled the vaccum ports,added a crank vent, I was running TBS needles but removed them after a few weeks thinking this was the problem. I had tried 1 and 2 shims with the TBS still no luck.
Over the last couple of months I have tried smaller mains,150's,145's no luck. Larger pilot,45's no luck.
I read on another forum someone suggested trying 40 pilots.
I'm puzzled, no combination seems to resolve the issue.
Just a thought, could it be the Thumb Idle mix srcews are to pointed to get a correct ajustnent?
Any advice is welcome.
Mike

Mike,
How does it run? Is there black smoke out the exhaust.
Black sooty plugs equals too much fuel. I would first check your float level, if it's out bend the tang to adjust.
Check the needle and seat, is there trash holding it open, is there deformation of either piece (soft brass)? Stick with the basics.

Check your Petcock. The stock ones suck. Once they leak, and mine leaked after 250 miles, fuel just pours into the carbs and fills up the float bowls. All the adjusting does nothing. So...set the petcock 'off', pull the fuel line off the carb side and set the line in a coffee can. Replace the petcock if ANY fuel gathers in the can.

The needle and seat should shut the fuel off once it reaches the proper level in the bowl. If not it would be running out of the carb overflow tubes.

So much fuel leaked out past the needles the bottom of my K&Ns were soaked and intakes were wet. I was filling 1/2 of a 1/2 lb.coffee can in 4 hours. Since the fuel is gravity fed the pressure was just pushing the fuel past the needles.

I forgot to mention that my vent tubes(tank and carb) were both pinched. The gas tank pressure just made the problem that much worse.

Pingel installed a year or so back. carbs are clean, float bowls look to be working properly.

it is funny that it just happened because i would figure with the pipes and jets you have would be very rich. have no idea why it would happen all of a sudden. wires and coils good? wonder if valves would have anythign to do with it

Frank

93 or 89 octane? some claim 93 fouls everything.

I assume that your thumbscrew idle mix screws settings... people can play with the strangest things when you aint looking. When was the time you checked/replaced your air filter? Could your exhaust system be partially blocked. It's just as easy to get too rich a mixture from not enough airflow as it is from too much fuel flow.

Matt

Jethro, I have heard both good and bad with 93. I have used
93 since the bike was new in 03 with a tank of 89 sometimes.
I changed over to 89 about 2 monts ago think the 93 could be the culprit. No dice same problem,back to 93.
Mike

Sandman, trust me those get checked weekly as I am constantly trying different settings.
The thumb screws are very pointed and the stock screws have more of a blunt tip. I'm beginning to think this could be the issue. They are very convenient for ajusting but it seems the problem started around the time I installed them.
I understand a lot of members are using them with good results but.............
Mike

Long shot. but have you looked to see if the K&N's are dirty? How long since they were installed/cleaned last? If they are very dirty, they will restrict the airflow sufficiently to cause rich running. Or did you over-oil them - this is easy to do.

Regards

Jan

Check to make sure your choke plungers are closing all the way or not worn out.

Sounds like a choke foul.

Quote:

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Are you positive the little O-rings and washers are up in there?

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Bingo! I would bet this is the problem!!!
You are probably flooding the crap out of it.
Black plugs are a sign of flooding with too much gas, or NO air. But with no air, it will eventually just stall out.

Bonny, It's not like I installed the thumb screws and the next day the bike went to hell. This has slowly been building to a problem
Yes, I'm positive everything is in place.

K & N's are clean.

The thumb screws might be the culprit do to the design,but the O rings etc are installed properly. I have had the thumb screws installed for several months. They look nice and are easy to adjust but I never really had a problem adjusting the stock screws.
I plan to try the stockers again this weekend, why not I've swapped everything else around a dozen times trying to figure this out.
Any chance it could be coil related? Both sides fouling?
Mike
Mike

I just rode in the rain and one side fouled. Once the bike was dry no problem. Plug wire? Coil? Plug?

Bonnyusa, I see you have 150 mains listed, if my memory is correct you were running 160's. If so why the change?
Mike

Bk, That's interesting. How can I determine if the choke plungers are operating correctly.
thanks,Mike

I was running a little rich (black plugs) so I decided to play. Went to 150s and lost no power and plugs are a little cleaner.

I believe the TBS needles 'caused' the rich condition which I swapped to cure the mid-RPM slump.

However, I have never fouled a plug in the true sense of fouling a plug in Raven.

Mike, are we talking about your plugs being REALLY black or are you actually fouling a plug (aka a short between the electrodes)?

As I know it from my two-stroke days, when you foul a plug, you lose that cylinder...

Plugs are very black and sooty and bike runs like s**t?
Mike

Mike,
How "modified" are your stock pipes? I have a 3/4" hole in every baffle with the 2 rear chambers and tubes removed. I started with 138 mains and worked my way down to 130 mains now. I am still a tad rich, but I can live with it. I'd like some 128s or even 125s. My plugs look tan and clean, but around 500-700 miles, the low end starts cutting out bad when warmed up. I change plugs and it runs great. Either my exhaust valve gaps are too big or I may need to 'Lower?" my floats a little. So, I'll re-shim and see what that does - and tinker with my carb floats a little. Just seems to me that 158 mains would be "way yonder more" richer than need be. Just a thought. I am also going to get some red plug wires from Brent, but I am not sure which brand to get.
Got a splatter of rain here tonight, but it's gone already.
Ride Safe,
Dennis

Hi Dennis, Are you running a stock air box? I have you completly removed the air box (Freak Kit)installed. This is the same set up (158) I have been running for about two years with no problems. My pipes are similar to what you stated. 4 1/2 " holes in third plate, last two baffles and tubes removed.
I suspest my problem could be valve related. 19000 and only one valve ajustment at 500 miles. Been putting this off for a while because it is just one of those things I did not want to tackle even though I do most of my own service work and upgrades.
I took the bike to my dealer Saturday to get the valves ajusted and see if they could help determine what is causing the problem.
Mike

Mike,
I've been putting off the valves too, just wanting to do it myself. But I can't stay of the seat long enough.
I'll change plugs again and do the valves next week.
I think we're having the same problem. By the way, my airbox is field dressed with a UNI filter.
Ride safe,
Dennis

Hi Mike,

Well you stated that you changed your mains down with no positive effect (maybe go even further down (135?)).

About the only thing I would suggest is an exhaust gas analysis to see if you can see what is going on...