Ok long story short, old motor blew, swapped new one in (20k on engine) carbs ran fine on old engine. When we put it back together, started right up and idled. Now (couple days later) wont start, and when it does, it doesnt want to idle. Cleaned carbs when bike was apart. Bypassed fuel pump, same result. New plugs, new battery, new starter. Any ideas? Bike is 600f3

 

Did you check to see if you've got fuel in the float bowls ? Probably something simple, if it was running before. Idle set too low ? Is it running rough when it does run ?

 

Yeah there was fuel in bowls, tearing it back down tonight, hopefully i just missed something

 

Pulled the plugs, all have good spark. But only 1 and 2 Are sparking on startup. 1,and 2 were wet when i pulled them, 3,4 were bone dry. Could my carbs be that out of whack? We bench synced them to get it running after new motor. I'm about to give up

 

Is 1 & 2 are sparking at the same time, or out of sync with each other?

On the F2/F3, CYl 1 & 4 should both be fed off the same coil, and 2&3 off the other. firing order is 1-2-4-3. I also believe that 1 & 4 should spark at the same time, and 2 & 3 will behave the same way. (wasted spark setup)

If you're not seeing that behavior out of your plugs - there's something wrong.

If 1 & 2 are firing at the same time, then you have your plug wires run to the wrong coils, but you still haev the problem that the other coil isn't firing.

If 1 & 2 are firing at different times, then both coils are working, but not both sides of each coil.

follow the troubleshooting in the service manual. Also - there's a typo in the downloadable manual on the first page of the Ignition section - the diagram shows 1&2 on the same coil and 3&4 on the other - this is not correct. 1&4 and 2&3 is the proper grouping.

 

Coils are the exact way they were on old motor, started idled and ran fine. Could my timing have jumped? How would i check the timing/adjust it?

 

timing is fixed - the pulse generator rotor is keyed to the splines on the crankshaft in a way that it can't be put on any other way, and the hall-effect sensor is not movable. The only way to adjust the timing is to get an adjustable pulse rotor, or one that is made with a few degrees advance/retard built in - even with those, again you wouldn't be but a few degrees off, so you should see spark on all 4 plugs.

 

Well almost embarased to say it, but problem is mostly resolved. When I swapped the new engine in, i used two of the carb boots of the old engine and two off of the new. somehow I completely missed the fact that they were different sizes.. not sure how I missed that, but I was rushing, and never did it before. I still have some stuff to work out on the bike, but it is starting, idiling, and running on all four cyl. now!

 

Sweet, that's great news. I love hearing back when people fix things. That way everyone learns what worked. Congratulations.