screamnz Posted May 30, 2007 Share Posted May 30, 2007 I just purchased an 1977 xs400 for $75. Over all it is in good shape, except the carbs. The last time it was on the road was in 2003. The owner pulled off the carbs and put them on the shelf until now. The carbs are frozen, I cant get the butterfly valves lose. I have been looking for a new set of carbs, but all I can find are carbs for the xs650's. Does any one know if these will work on a 400? Also I would like if possible to switch from CV carbs to slide carbs. Does anyone know if the RD carbs will fit? Link to comment Share on other sites More sharing options...
Moderator drewpy Posted May 30, 2007 Moderator Share Posted May 30, 2007 I just purchased an 1977 xs400 for $75. Over all it is in good shape, except the carbs. The last time it was on the road was in 2003. The owner pulled off the carbs and put them on the shelf until now. The carbs are frozen, I cant get the butterfly valves lose. I have been looking for a new set of carbs, but all I can find are carbs for the xs650's. Does any one know if these will work on a 400? Also I would like if possible to switch from CV carbs to slide carbs. Does anyone know if the RD carbs will fit? any 34mm carbs should fit except 2 stroke ones (i think they are designed different due to the 2 stroke oil, but don't quote me on this) need to put on a dyno afterwards to get the fueling curve right Link to comment Share on other sites More sharing options...
dragonnoodle Posted June 15, 2007 Share Posted June 15, 2007 The carbs from the '80 and up xs650s are Mikuni BS34mm CV carbs and they are jetted the same as the xs400 carbs, at least from what I've seen. Go to a yamaha oem parts site and look up the carbs for your bike and the carbs from the bike youare getting and compare the specs just to make sure. The xs400 had three or four variations on the mikuni BS34mm CV carbs. Link to comment Share on other sites More sharing options...
socalyamaha Posted October 22, 2007 Share Posted October 22, 2007 what about the spacing for the inlets? i've heard the exhuast between the two is interchangable as well. can anyone confirm that? Link to comment Share on other sites More sharing options...
Moderator drewpy Posted October 23, 2007 Moderator Share Posted October 23, 2007 what about the spacing for the inlets? i've heard the exhuast between the two is interchangable as well. can anyone confirm that? the exhausts are different on the 650 as they splay out a la triumph. you will need to rejet a 650 carb or you will be overfuelling because of the extra CC's of the 650 Link to comment Share on other sites More sharing options...
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