reserve fuel tap question?

[timsutcliffe]

Hello,
I have recently got a 1979 C90. It is great but it's my first and I don't really know much about it. Today it started the power seemed to start cutting out, I was holding the throttle steady at about 30mph but it was slowing down suddenly like the throttle had been let off and then starting again. When I slowed down and stopped it stalled and I couldn't start it again, but then a few minutes later it did start fine and was ok for about a mile before it did the same thing again. I checked the fuel tank and there is definitely petrol in there although it's hard to see how much. Someone told me there was a reserve fuel tap that might have something to do with it. Can anyone help? where is the reserve tap? Will this help? I also heard you are supposed to turn the fuel tap off overnight to stop petrol going into the carburetor. Is this the same tap? My manual hasn't arrived yet or I'd look it up. Any help would be welcome. thanks in advance. Tim

[Leiba]

Have you got two pipes going into the carb? if no, then you have no reserve. If yes then you do. The tap (lever) can be got to from the left side (as you sit on it) of the bike. You should be able to read 'on', 'off' and 'res' on it, not sure in what order though.

[timsutcliffe]

IMG_1983.JPG

I can see one pipe on the right side but on the left side I can't see any lever or tap but I found this cable which has disconnect from something. Is this one of the pipes you meant or something else?

IMG_1984.JPG

[wightegi]

that is a drain from the bottom of you float bowl the tap is on the other side pipe or pipes higher up the carb.

[timsutcliffe]

Thanks very much for your help

[Leiba]

If you've only got one pipe then you haven't got reserve.

[Jon]

Hello,
I have recently got a 1979 C90. It is great but it's my first and I don't really know much about it. Today it started the power seemed to start cutting out, I was holding the throttle steady at about 30mph but it was slowing down suddenly like the throttle had been let off and then starting again. When I slowed down and stopped it stalled and I couldn't start it again, but then a few minutes later it did start fine and was ok for about a mile before it did the same thing again. I checked the fuel tank and there is definitely petrol in there although it's hard to see how much. Someone told me there was a reserve fuel tap that might have something to do with it. Can anyone help? where is the reserve tap? Will this help? I also heard you are supposed to turn the fuel tap off overnight to stop petrol going into the carburetor. Is this the same tap? My manual hasn't arrived yet or I'd look it up. Any help would be welcome. thanks in advance. Tim

Hi Tim. Your problem could well be a blockage in the fuel line. Others will hopefully chime in to tell you where the filter is on your model. although fuel is getting to your carburetor it is not flowing very fast and the bike is using up the fuel faster than it can be replaced. That's why the bike stops and then starts again a little while later...The carb has had a chance to refill.
Although it is good practice to turn the fuel off after riding it isn't critical as the carburetor has a device just like you'll see inside a lavatory cistern tank to stop it overflowing.

You can check this by getting that rubber pipe you are holding in the picture, finding a screwdriver and undoing the screw that is visible at the bottom of the carb...Near where the rubber pipe starts. Turn your petrol 'off' at the tap and loosen the screw on the carb. You should see an egg-cup full of petrol come out of that pipe. (catch it in a glass so you can look at what comes out) . Once it has finished turn the petrol back on and the flow should start again and come out at least as fast. if it doesn't, then you DO have a blockage. if it does, the problem might be something else but the petrol in the glass might hold a clue...Look for blobs of water in the bottom or particles of dirt. Once you've done that try the bike again...It might be OK now!...Just letting the fuel run through can sometimes clear things out!