Carb Icing woes - Ducati.ms

yets · Jan 19th, 2012, 7:28 pm

My 750ss (91' Carb), I suspect, is suffering from carb icing. It's been really cold over in the UK recently, talking freezing conditions. On Monday, took out 750ss, tried warming the bike up but I had no power in lower revs. But as the revs go higher it seems better. It would accelerate really slowly I had to go to work and out of the 4 mile journey, the last half mile the bike returned to normal operating parameters. Since then, no longer how much I have warmed it up (even when the weather has warmed up) I am still having the same problems.

Is my main issue carb icing? Surely when the bike warms up after a while the carbs should be ok? I've bought somr Pro FST; do I need to put it in the tank first? ARe my carbs cooked?

REVNH · Jan 19th, 2012, 10:03 pm

I'm probably not much help other than to tell you that a warm motor does not mean you can't ice the carbs. I'm not saying that is your issue, but I can tell you first hand from years of riding a snowmobile that a hot motor doesn't prevent carb icing. That said, when was the last time the carbs on your bike were apart and cleaned?

Mad Dog · Jan 20th, 2012, 1:06 am

typical SS problem. Had that on my 93SS and I found that by saturating the engine with a long warmup in the morning, usually about 5-minutes, I would get long runs before the carbs started to ice again, usually with a backfire and a stall. Letting the bike warm up the carbs with residual heat in about 5 minutes usually let me start off again. Any fast warm up on a cold morning would not get me very far.
Also, there is a carb warming set up for those models, if you can find one, and they direct warm oil to the carbs in order to eliminate the problem. Never used or saw one, but my warming technique let me ride all year round in pretty cold weather.

countcoupe · Jan 20th, 2012, 4:22 am

Yeah, just whack some pro fst in the tank with the fuel and see if it helps. I don't think you have to be overly scientific with the quantity's!

The carbs sat out in front of the engine on sticks means they don't get any benefit from the hot engine!
It also dosent have to be overly cold for the ss to suffer from carb icing! Razzing along in moderately cold weather can cause a bit of a wind chill factor and cause the carbs to misbehave!!

Have you ever balanced the carbs? Simple to do (if you can borrow some vacum gages) and can make all the difference.

I assume your bike ran great b4 the cold weather?

Chaz

Joe-B · Jan 20th, 2012, 7:17 am

Big problem riding to work on chilly mornings here in Wyoming. I got so fed up I went to Keihin FCRs. Expensive solution, but they don't ice up (and the bike runs WAY stronger with the FCRs

!).

yets · Jan 20th, 2012, 10:21 am

Yeah, the bike was working perfectly well before the cold weather hit. My boss (previous owner) is wondering if it is actually carb icing though as it's not typicaly carb icing issues. It starts fine but idles at 1k revs and no matter how hot the engine is, it never seems to go above 1.1/2k. There's is just no power for some reason. It's baffling. Silkolene PRO FST doesn't seem to be helping too. Could it be the spark plugs?

Edit: Sorted. It was my spark plug. Was running on one cylinder, seems that I've been keeping my choke on for a little longer than I should do due to the freezing cold weather and have been fouling spark plugs. Thanks for all the help, I'm very greatful. A great site filled with great members.

countcoupe · Jan 21st, 2012, 2:38 pm

Good to gear it was a simple fix.