Fairing / Carb issues

[Eveready1100]

About 6 months ago, I fitted a BMW R100/RT Fairing to my '79 Special. Fitment of the inner panels was a very snug affair with the tank but it ended up all going together well. Took it for a run up the coast the next weekend and the fairing proved a godsend as we hit a few showers on the way up. Protection from the rain was excellent and our intercom system suddenly worked very clearly at all speeds. The only thing that seemed a bit odd was that the bike seemed to be surging a bit at highway speeds though I thought it might have just been a new sensation due to the lack of wind blast at speed. I slowly got used to the feel of the bike till I hardly noticed it.
I later took delivery of a 24 litre tank to improve the range a bit and one glance told me that the fairing inner panels had to go. Tank fitted and took it for a run and the surging had eased a bit. This got me thinking that maybe the fairing was generating a vacuum effect around the carb area or something to that effect. I rode the old girl around for a few months like this till the other day, some moron in a car decided he wanted my lane and forced me into the curb. I nearly had it stopped when I hit the edge and the front washed out then down we went. No serious damage to the bike (or myself) though the side of the fairing was scratched badly. Typically, the car driver vanished from the scene. Anyway, I get home and took the fairing off. Next morning, the ride to work was a revelation. The motor ran smooth as silk with no sign of any surge at all.
Now I'm asking if anyone has experienced a similar symptom by fitting a fairing to their bike. B.T.W. My Special has stock pipes, carbs and airbox. Any feedback to help possibly avoid the effect when I refit the fairing
would be greatly appreciated.
Thanks,
Errol.
Some pics can be found at /http://www.ulyssesredcliffe.org/ in the ride photos section.

[mitch]

air

You might try drilling your air box to allow more air to your carbs, you might of cut down the flow and could be running rich. HTH.....................MITCH

[Jerry]

I run a Vetter IV (same as SS) with lowers I put on in the fall, no problems with carbs that I have noticed. This is my 3rd season with them.

[skids]

Re: Fairing / Carb issues

I have three xs1100's and all have been run with and without Vetter farings, one was also run with and without a Plexistar windscreen. There has been no differences in the smoothness of the engines with/without. I do have one that acts up with it rains or when I wash it. I have not come to terms with that yet and sometimes it takes quite a while to clear itself.

Originally posted by Eveready1100

Now I'm asking if anyone has experienced a similar symptom by fitting a fairing to their bike. B.T.W. My Special has stock pipes, carbs and airbox. Any feedback to help possibly avoid the effect when I refit the fairing
would be greatly appreciated.
Thanks,
Errol.
Some pics can be found at /http://www.ulyssesredcliffe.org/ in the ride photos section.

[Geezer]

I don't think the fairing is the cause but rather it makes the problem obvious. I'd start with making sure the fuel filter and air filter are clean. When was the last tune up done? Do all the usual tune up stuff to eliminate it as a possibility then try again.

This could end up being one of those picky little problems that takes forever to solve and once fixed in hindsight it should have been obvious. ;o)

Geezer

[MartyA]

I have a Vetter, and after riding for 3 years without it I finally mounted it. You get used to feeling the wind on your chest and then after the fairing was on you don't feel the wind like before. The one thing I noticed is the strong shifting wind currents can make you feel like the bike is surging. Since the wind is hitting the fairing and not you, you wouldn't notice the change in wind. I can slow down up to 5 MPH when I pass an oncoming 18 wheeler oncomingwhen that wind hits. Following one can be a treat also. I find that those mini-vans create surprising currents when you are following one. The bike does surge a little, and I get some helmet buffeting also. I hate following them.

I would be surprised to find the fairing alone would be the cause of the carb surging. It is probably the wind hitting that barn door of a fairing. You just don't feel it on your body, what you feel is the bike slowing.

[Eveready1100]

I finally got around to refitting the fairing in time for a 1500 klm Easter ride.
I made a new adapter up where the main bracket bolts to the headstock with a spacer included to tilt the whole thing back about 10 degrees from what it was originally. The surging problem (or whatever) has disappeared and fuel economy has picked right up with a range of about 390 klms before reserve. Thanks for your advice. I'm doing my carbs and shims this weekend, if I'm not out riding somewhere.
Thanks again.
Errol