stevendefense Posted May 2, 2008 Share Posted May 2, 2008 Hi all. I recently bought a 1979 xs400 to ride over the summer and then restore/modify over next winter. I am fairly new to motorcycles in general and very new to Yamahas. The bike has a couple of issues as it sits right now that I am trying to work out. The biggest problem I am having so far is locating parts. Could anyone point me to a good parts supplier or a listing of parts that are interchangeable with other bikes? Any help would be greatly appreciated. Link to comment Share on other sites More sharing options...
jrhendryx Posted May 2, 2008 Share Posted May 2, 2008 Hi all. I recently bought a 1979 xs400 to ride over the summer and then restore/modify over next winter. I am fairly new to motorcycles in general and very new to Yamahas. The bike has a couple of issues as it sits right now that I am trying to work out. The biggest problem I am having so far is locating parts. Could anyone point me to a good parts supplier or a listing of parts that are interchangeable with other bikes? Any help would be greatly appreciated. is there a specific part that you need to make it ride-able? a lot of items on all of the older bikes (esp the xs series from what ive found) are interchangeable, except when it comes to motor parts. suspension parts especially are bin parts. welcome! Link to comment Share on other sites More sharing options...
stevendefense Posted May 2, 2008 Author Share Posted May 2, 2008 I need a new fuel petcock. When turned to the off position fuel pours out of the left carb. I am pretty sure that the vacuum diaphragm is shot. From what I can find, a mechanical type petcock from a xs650 should fit. I think I may need a new coil also but need the get the fuel issue figured out first. Other than that I was mainly curious about upgrade parts, seats, tanks, pipes and so on. I also would like to convert to an electronic ignition setup. There doesn't seem to be a huge after market for the 400, and I am hoping that some of the more common 650 hop up goodies may work. Any ideas on where to look? Thanks for the help. Link to comment Share on other sites More sharing options...
jrhendryx Posted May 2, 2008 Share Posted May 2, 2008 I need a new fuel petcock. When turned to the off position fuel pours out of the left carb. I am pretty sure that the vacuum diaphragm is shot. From what I can find, a mechanical type petcock from a xs650 should fit. I think I may need a new coil also but need the get the fuel issue figured out first. Other than that I was mainly curious about upgrade parts, seats, tanks, pipes and so on. I also would like to convert to an electronic ignition setup. There doesn't seem to be a huge after market for the 400, and I am hoping that some of the more common 650 hop up goodies may work. Any ideas on where to look? Thanks for the help. mikesxs.com is one place that i have found some of the parts that work out. they carry the petcocks you need... though yours must be vacuum, mine are manual. i think that they carry the vacuum kind too. yamatopdog.com is another good place to look for NOS parts. Link to comment Share on other sites More sharing options...
stevendefense Posted May 2, 2008 Author Share Posted May 2, 2008 Thanks for the suggestions on the parts suppliers. Can a mechanical type petcock be retrofitted to work in place of my vacuum operated one? It seems to me that the vacuum system is an over complication. Link to comment Share on other sites More sharing options...
jrhendryx Posted May 3, 2008 Share Posted May 3, 2008 Thanks for the suggestions on the parts suppliers. Can a mechanical type petcock be retrofitted to work in place of my vacuum operated one? It seems to me that the vacuum system is an over complication. i believe so.... there ought to be a vacuum barb somewhere on the carb that you cap off when you change from a vacuum to a manual petcock. i dont know - i dont have much experience with the vacuum systems. Link to comment Share on other sites More sharing options...
Cy Welch Posted May 4, 2008 Share Posted May 4, 2008 i believe so.... there ought to be a vacuum barb somewhere on the carb that you cap off when you change from a vacuum to a manual petcock. i dont know - i dont have much experience with the vacuum systems. Both carb holders should have a vaccum barb on them, one should already be plugged and the other should be hooked to the petcock, just cap that one when changing the petcock and your good. Link to comment Share on other sites More sharing options...
bralkan Posted May 5, 2008 Share Posted May 5, 2008 Hi all. I recently bought a 1979 xs400 to ride over the summer and then restore/modify over next winter. I am fairly new to motorcycles in general and very new to Yamahas. The bike has a couple of issues as it sits right now that I am trying to work out. The biggest problem I am having so far is locating parts. Could anyone point me to a good parts supplier or a listing of parts that are interchangeable with other bikes? Any help would be greatly appreciated. not to imply anything, but as far as I know there is no off position on the stock petcocks. It is reserver, run, and prime. Prime will allow free flow of fuel. Parts can be found on ebay, partsnmore.com, mikesxs.com, and you can also try oldbikebarn.com as far as electronic ignition goes, it may take some re-wiring but you may be able to get an electronic ignition from a 1980+ xs and replace it....not sure though. Link to comment Share on other sites More sharing options...
Cy Welch Posted May 5, 2008 Share Posted May 5, 2008 not to imply anything, but as far as I know there is no off position on the stock petcocks. It is reserver, run, and prime. Prime will allow free flow of fuel. Parts can be found on ebay, partsnmore.com, mikesxs.com, and you can also try oldbikebarn.com as far as electronic ignition goes, it may take some re-wiring but you may be able to get an electronic ignition from a 1980+ xs and replace it....not sure though. Additionally on those I have seen, lever straight down is on, forward is reserve and facing the rear is prime. Putting it in prime will indeed tend to make gas run out the carbs if there is ANY problem with the needle valves. I would suggest that if there is no problem with the lever straight down there is no reason to replace the petcock. Actually I find that if they are working properly it's much simpler since you don't have to remember to turn the fuel on and off each time, since starting the engine turns it on and stopping it turns it off. My 27 year old petcock works just fine, while the one I got on a replacement tank doesn't (but then I haven't really spent any time trying to fix it either). Link to comment Share on other sites More sharing options...
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