i bought a 1980 xs400 and cant get it started

[RadianRider]

Hey guys, well I bought what I believe is a 1980 xs400. When I bought the bike it was just a big pile of parts.this isn't my first bike so I figured I could get it running, but this bike is giving me Hell. I'v gone through the carbs with carb cleaner 4 or 5 times now and it is squeaky clean the plugs have been replaced and have a good spark the bike has good compression. If I spray starting fluid in the carbs I'll get a few backfires but that's about it. I'v gone through everything I could think of. It is a bit cold at about 38° that might have somthing to do with it but my yx600 fires up fine at this ttemp. I would like to hear any ideas

 

[levdir]

This is kind of a stupid question but have you been starting it with the choke on?

 

[RadianRider]

Yeah I'v tried with it on, off and 1/2 choke

 

[levdir]

I assumed you must have given the thoroughness of your description, just covering the bases. Do you know if a PO changed the jetting at some point?

 

[RadianRider]

The PO said it was all stock. So as far as I know the jets have never been changed.

 

[motoTrooper]

check the connections to the coils. There is an orange wire and a gray wire coming from the condenser. Can't remember off the top of the head which goes to which, but with a 180 degree firing order they make a massive difference if they are connected wrong. Had the same issue when I put mine back together for the first time and tried to start it. No go, weird firing, switched the wires and boom, back in business.

 

[RadianRider]

Yeah I'v looked at a wiring diagram and checked it, I'v tried swapping the wires around too

 

[Unkle Crusty]

My 83 Seca will only fire with full choke and no throttle. Have you checked for fuel flow to the carbs? Maybe disconnect the fuel line and turn the lever to prime. If you have fuel flow, try firing the bike on prime.

Unkle Crusty*

 

[xschris]

Did you fully disassemble the carbs when you cleaned them and make sure they where adjusted to spec? Does the bike have the exhaust on it with the factory air filters? Post some pics of the bike. Also make sure you have a full charged battery and a set of new plugs in it.

 

[RadianRider]

I'v gone through every little hole and taken the whole thing apart a few times, I bench synced it I have the stock exhaust. For the air filters I have oiled foam over the old stock filter frame. What I suspect it to be is an electrical problem because when I got the bike the wiring harnes was pulled out. Although I do get a good spark from my plugs which are New. Also after I crank the engine over I hear clicking from one of the relays for a second or 2. And do these bikes have any problem starting in the cold because it stayes about 35°

 

[RadianRider]

And I'll post some pictures later when I get home

 

[Unkle Crusty]

Mine starts on first crank at 39, a couple of cranks at 35, and quite a few more cranks at 25. Mine is DOHC motor, but I think they would fire about the same.

Unkle Crusty*

 

[RadianRider]

Will this bike start with the clutch engaged because the sprocket cover has been off since I got the bike and that's where the clutch cable attaches so Idk if that might have somthing to do with it because I'm not sure how this clutch works

 

[xschris]

Doe the bike have two relays located behind the motor? If so it's a 81 bike. One is the safety relay ( which you need to pull the clutch in to get the e-starter to work) and the other is the headlight relay. Does all the lights work? If the wire harness was out something may be missing or wired wrong. Check the manuals wiring diagram to much sure it is correct. Clicking may be a week battery. What weight oil do you have in it? I would put some lighter oil in it if you are going to run in 30* temps.

 

[RadianRider]

Yeah it has 2 relays just like that. Will the bike start with out the clutch if I jump the solenoid? The lights do work I don't have blinkers on it yet. I'm using 20-50 which is probably a bit thick

 

[xschris]

Then yours is a 81. What is the first three letters/numbers of the vin as that will tell you the exact bike you have. I would go to a 10-30 wet clutch oil. If you jump the solenoid the bike will turn over. But since you never herd the bike run there may be issues with the motor and or the ignition system. I would check the compression, make sure the valves are set right and make sure the plug wires are going to the correct cylinders. If all that checks out goo the you may have problems with the TCI box or the ignition pickup coil.