Hey guys I'm looking for some insight on some issues I'm having with my twin cam build. Rebuilt top end, 103 jugs, pistons, rings, cams, lifters, push rods, oil pump, cam plate, etc. Also rebuilt primary side stator, rotor, screamin eagle compensator Sprocket, stater clutch, etc. The issues I'm having are misfire, backfire, rough idle and stalls out. This is on initial first start up after build. I guess another thing to mention i had the bike painted so the tank sat dry for couple months. I have opened cam cover and rechecked my timing marks all line up. However, I believe my tdc on front cylinder is off somehow. Maybe I'm over thinking this but the timing marks on sprockets are not 180 degrees apart and in line. They are over on the right a bit. I'm checking for tdc with a paint brush. The rear cylinder tdc is lined up with marks closest together. Could be over thinking and maybe it's just a fuel issue but I wanted to start here since I made big changes and bike ran ok prior to rebuild. Thank you all in advance

Tdc

Tdc

 

Do yourself a favor You have gone that far pull the cams and double check. Don't ask me how I know (LOL) Your timing chain looks correct but it sounds like the two Cams are not timed together.

 

Youre sprockets are timed right but like dishman said your cams could be off a tooth. Also check that your pushrods are in the right location. What are you tuning with? Canned tune or dyno? Time to retrace your steps...its usually something simple

 

Thanks for the replies. I will triple check cams but I believe they are spot on. Push rods were intake inside exhaust outside. Can tune for now with power vision from Fuel moto but I will be putting it on the dyna at cycle rama in a couple weeks. I did the front cylinder push rods with timing marks 180 apart lined up which now I have found that not to be tdc for front cylinder. Maybe they weren't on the bottom lobe of cam completely? Am I correct on the timing marks looking off for front cylinder? Thanks again

 

switch the spark plug wires around,ive seen more than one guy tear his motor down after a build cause of backfiring & not running and it simply turs out to be they swiched the plug wires & didnt notice it

 

Pull a ccp test.
If f/r differs 20--25 lbs, you'll know you are off 1 tooth.
Scott

 

Also check O2 sensors for wires crossed. That will also give the symptoms you describe.

 

Plug wires are correct. I will try to find a compression tester today and do a test on front and rear. And unless 02 sensors themselves are specific to front and rear I believe I have them correct. Rear goes under seat and front goes near voltage regulator. Just want to eliminate possibilities 1 by 1 and try to handle this methodically but I know it could be so many things! A bit frustrating after so much time in the bike. Thanks for all the help. So nobody thinks tdc on front cylinder timing marks look funny?

 

One thing I just thought of as a high possibility. I pulled fuel pump fuse and cranked starter 3 or for times for 5 seconds to move some oil around before initial start up. Problem is I didn't have plugs in wires therefore not grounded out. Could this have damaged the coil? I read somewhere to ground them out when doing this and I just overlooked it.

 

Absolutely a must.....