don007 Posted September 27, 2017 Share Posted September 27, 2017 Hello, my 79 XS1100 has been running fine up until last night. This is 4th actual time riding it, I've rode previously from getting from the shop weeks ago but now put some issues on myself. local shop everything that was fixed/replaced. * fuel line replaced * dirt bags used dot 4 brake fluid, but haven't encountered a problem...yet . I even gave them the manual. *carb washers were replaced (and carbs were actually rebuilt when bought it from the owner.) *gasket float chamber *rebuild kit for rear brake. *60/55W halgon h4 ( recently did) Yesterday I pulled the choke out for a few seconds and even rode with it out. Reason being because I had recently started turning my petcocks to OFF thought it needed some fuel to go through. I honestly don't if I should turn petcocks OFF after when not parked and not in us? But I obviously set them back ON, this is the time where I encountered a problem. I was accelerating fine and slowing down fine up until a few minutes later I could not accelerate my bike even if tried shifting, I stopped in a parking lot to let choke out in let the bike sit neutral. I haven't rode my bike for 2 days that's actually when I started setting the petcocks OFF because I read that you should get in the habit of doing it so nothing clogs. As I was letting it run in the parking it sounded like it warming up maybe or that everything was feeding right at a steady 2 rpm on neutral. let it sit for 5 minutes then took it out down the street. Everything seemed to run and shift fine but again I encountered the accelerating problem it's almost like a dull sound from the exhaust not what it would normally sound like. Stopped in another parking did the same thing again let the choke out then took it back home. Also I noticed when I left to choke out and revved it a little and let off the throttle the rpm was high that's when i pushed the choke back in (while stationary in neutral). Another thing I did was fill the fuel tank to brim almost, I read that's a no no. When I finally turned off my bike I heard pressurized hissing sound coming from cap, I opened then shut it. The sound went away. Too much pressure/air in fuel tank perhaps at the time? I feel like problems started occurring when I messed with the petcocks for the first time.I will add an audio file soon. I apologize for the lengthy paragraph. Thanks. Link to comment Share on other sites More sharing options...
JimR Posted September 27, 2017 Share Posted September 27, 2017 Hi first off the xs1100 petcocks do not have an off position they have on-res-pri .. the pri position allows fuel to flood tho where as on & res only supply fuel when a vac is formed via the engine being started .. you should only use the PRI position on the petcocks to 'prime' the carbs with fuel after work on either the carbs and/or motor. However with the age of XS1100 you may have knackered the diaphrams within the petcocks. The Dull sound from the exhaust sounds like the fuel lines have been routed wrong .. have you removed the carbs and/or the fuel tank recently ? Link to comment Share on other sites More sharing options...
don007 Posted September 27, 2017 Author Share Posted September 27, 2017 You may not be able to see with this picture but my petcocks have Are indicated in this order from left to right R ON OFF And I have not removed the exhausts or fuel tank. Like I mentioned before it all started when I decided to set them on the off position. Link to comment Share on other sites More sharing options...
jimmy Posted September 27, 2017 Share Posted September 27, 2017 My 79 xs1100 had vacuum carbs so no on/off. Maybe the US Model was different, or maybe some previous owner changed them. Anyway reading your post when you stated that "Another thing I did was fill the fuel tank to brim almost, I read that's a no no. When I finally turned off my bike I heard pressurized hissing sound coming from cap, I opened then shut it. The sound went away" tells me that tank breather is blocked. You will need to clean out the breather hole in the cap Try running the bike again and when it starts to bog down open and close the petrol cap and see if that clears it. 1 Link to comment Share on other sites More sharing options...
JimR Posted September 28, 2017 Share Posted September 28, 2017 On 27/09/2017 at 4:19 PM, don007 said: You may not be able to see with this picture but my petcocks have Are indicated in this order from left to right R ON OFF And I have not removed the exhausts or fuel tank. Like I mentioned before it all started when I decided to set them on the off position. Those petcocks are not as Yamaha intended ... which may indicate some issues .. looking at them they look like Kawasaki petcocks which are not vac controled .. I guess the 2 vac take offs on the inlet manifolds have been blanked off so no undue air is being allowed into the inlet tracts ? I would doubt that Yamaha would have given the UK vac petcocks and the US manual ones from my time at the factory they would use as many common parts across as possible through models for different markets ... I would guess your after market petcocks are just not allowing the volume of fuel through to allow the engine to run Link to comment Share on other sites More sharing options...
don007 Posted September 28, 2017 Author Share Posted September 28, 2017 Fuel shut off valves, aren't the same thing as petcocks. The thing was I thought having them OFF is what I was suppose to do when parked but apparently that wasn't a good idea? Jimmy I let it run with cap open for a few minutes, it sounds normal like it did when I had got it. I thought putting in an extra gallon wouldn't really matter but I suppose it does. Link to comment Share on other sites More sharing options...
jimmy Posted September 28, 2017 Share Posted September 28, 2017 1 hour ago, don007 said: Fuel shut off valves, aren't the same thing as petcocks. The thing was I thought having them OFF is what I was suppose to do when parked but apparently that wasn't a good idea? Jimmy I light it run with cap open for a few minutes, it sounds normal like it did when I had got it. I thought putting in an extra gallon wouldn't really matter but I suppose it does. Don What I meant was let the bike run with the fuel cap on until the bike starts to bog down, then release the cap whilst the engine is running. This will indicate whether the vent in the cap is blocked. I would ride round the block a few times as it's not a good idea to run an air cooled engine in the stationary position Link to comment Share on other sites More sharing options...
blackhat250 Posted September 28, 2017 Share Posted September 28, 2017 Them pod filters are gash too, i bet it takes ages to warm up.[ cough & splutters].. usually runs lean also, , that hissing sounds like a vacume .[cap breather blocked,,] Link to comment Share on other sites More sharing options...
JimR Posted September 29, 2017 Share Posted September 29, 2017 However with the correct vacuum Fuel shut off valves, as you can see from the image the petcock is totally different to the one in your image without these there is a chance you may have to do some mods to get around your problems Link to comment Share on other sites More sharing options...
Recommended Posts