Dixie Posted October 4, 2018 Share Posted October 4, 2018 Hi All Long time no speak, finally got my rattle sorted and my carbs re-built, however, its still running really rich. Does anyone know what the needles should be set at on a 79 GS 750? Everything I have read suggests middle notch, but its still running rich. It's got a new air filter ,K&N copy of the original, but I'm wondering if I drop the needle will it run leaner, I assume so, but you know what they say about assumptions. Any guidance would be much appreciated as usual.Anyone??? Quote Link to comment
gs7_11 Posted October 4, 2018 Share Posted October 4, 2018 Forget the needles, that won't make that much difference. Have you checked the float heights? Blown through all the drillings to check they are clear? Checked that the float valves aren't leaking? Checked the emulsion tubes for wear? 1 Quote Link to comment
BigT Posted October 4, 2018 Share Posted October 4, 2018 What jets are in the carbs? What exhaust are you running? Quote Link to comment
wraith Posted October 4, 2018 Share Posted October 4, 2018 3 hours ago, gs7_11 said: Forget the needles, that won't make that much difference. Have you checked the float heights? Blown through all the drillings to check they are clear? Checked that the float valves aren't leaking? Checked the emulsion tubes for wear? +1 Also is it at the bottom end? If so like @gs7_11says floats heights or float valves, maybe be pilot jets as well, that's for bottom end running. Quote Link to comment
Dixie Posted October 5, 2018 Author Share Posted October 5, 2018 OK Standard jets are I believe 100 and I was told that 102 was what I should use by well known reputable supplier, so that's what I fitted. It's running a standard exhaust and i've found out one of the cylinders is low on compression, would this have an affect? I haven't checked the emulsion tubes to be fair. Quote Link to comment
gs7_11 Posted October 5, 2018 Share Posted October 5, 2018 (edited) If everything's standard, stick to the jetting in the book. My 750 ran perfectly on standard jets, I dont think there's any need to go up a size on the mains, although I doubt that's the problem here. Clean air filter and no blockages in the rubber snorkel at the back of the Airbox? Both screws in the pilot system set correctly? This isnt a jetting issue, Its a carb functionality issue, so there's a fault somewhere. Strip and inspect the carbs...every jet out, and use carb cleaner or compressed air to check every drilling is clear. Check all the jet and air jet sizes and float heights. Check the emulsion tubes for wear. Are you sure theres no flooding from the float valves? How are you measuring the float valves? It can be a good idea to fit a new set of o-rings to the chokes and float valves, you can get them from cycleoring.com. Edited October 5, 2018 by gs7_11 Quote Link to comment
Dixie Posted October 5, 2018 Author Share Posted October 5, 2018 I've fitted full service kits to all four carbs including 0 rings and ensured every drilling is clean, the air filter is new, my only concern is that it appears above the air filter there should be some sort of foam seal, is this correct, if so mine's missing. I'm intrigued by the emulsion tubes as I didn't check those. The weathers turning so I'm happy to strip and rebuild again. I'll let you know how I get on, thanks for everything for now, top advice Quote Link to comment
BigT Posted October 8, 2018 Share Posted October 8, 2018 How did you set the choke lifters? Should be notch down The K&N should make it run lean, not rich What size pilot jets are in it? Where are the fuel and air screws set? Is the low compression cylinder #3? Has the oil level gone up? Quote Link to comment
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