need help getting her started/running

[cyclocrossfool]

bought a 1979 xs 400f2 a week ago. she starts and sort of runs, but throttle must be on full. after a few seconds she quits. the battery is new and charged, we have gas. there is spark to both cyclinders, the plugs look good and have the correct gap,the air filters are clean. no obstructions to carbs. took the bowls off carbs, cleaned w/ carb cleaner and some air in jets, took top off. slides, needles, rubber on dia all good. butterfly and cable linkage all seem to work good. the engine has a little over 8000 miles. things a havent checked are compression and timing. the points look in great shape. no oil leaks in engine. oil changed. old oil looked great.i think thats it. it seems like we have gas and air. am i missing something??? i need help, thanks, CXF

 

[bcbobbers]

do you have good spark? also the carbs are probably still gummed up, they are a pain to get all the way clean, I know many people on here had to clean there carbs 3 or 4 times before getting them entirely clean. This is especially the case if the bike sat for a while. Did you also check the petcock to make sure it is working properly, it sounds like it may be getting not enough fuel especially if you gotta have the throttle open to get it to idle. Clean the carbs and clean them 3 more times. or take them to a shop and have them ultrasonically cleaned (works like a charm) Good luck...also an introduction of yourself and your bike would be nice.

 

[cyclocrossfool]

thanks for the info. the petcock flows good. the last reg decal on the licence plate was 90. so i think the bikes been sitting 20 plus years. i took the carbs off/apart again. all the jets out. is there something i should soak them in. or just spray them down w/ carb cleaner/air. any help is needed. ill post pics of the bike soon. i need to get the seat sorted out. the cover is torn bad. it might be cheaper if i bought a cafe type seat for it. thanks, CXF

 

[jlearning1]

Hello cyclocrossfool

I have just completed cleaning my carb. There are a few things I would say. When you take the 2 fuel bowls off there are 10 items that must be cleaned in that area. 1. 2 ea jet pilot #42.5. Remove those little black caps, and there is one jet in each hole. You will need a small flattip screw driver to remove them. 2. 2ea jet main #135 and 2 washers. You will see them, they both use a small screw driver. 3. 2 ea needle valve sets(needle valve will have a small screw on top of a horshoe clamp that must be removed) 4. 2ea Gas floats and pins. There are also 2ea Jet Main #160 on the top where the diaframs reside. They are screwed in the top sides of the housing. Good luck on your Bike, and I hope this helps

Thanks