Hey guys so I got the bike all put back together and start it up it starts back firing through the carb sometimes with flames lol. The only way to keep it running is to throttle it otherwise it dies. I recently did the top end on it new jugs pistons and rings. I lapped in new valve and seals. I didn’t make any adjustments with the carb or cam or anything else. It did not do this before the rebuild. It’s a 1987 flhtc evo . Thanks in advance .

 

Check air leak at carb manifold.

 

Did you increase displacement? Usually a sneeze out the carb is a lean condition. If you did increase- then id rejet the carb. If you didnt-Id recheck your timing.
but the manifold seal thing makes more sense.

 

Did you get your voes hooked back up and vacuum hose connected to the carb?
If yes, you have a bad intake leak, probably where the rubber compliance fittings bolt to the heads.

 

oh yeah I got that lol it was hiding under the seat when I took it off .

 

okay will do. Not looking forward to taking the gas tank off again but I guess I’ll have to

 

I have a hanging 1/2 gallon lawn edger fuel tank that I like to use for "first startups"

 

Stock or adjustable pushrods?

 

Before you take the tank off-if you can find a small mirror and flashlight to look at the manifold and maybe you can spot something obvious-. If you can keep it running a bit- you can try spraying carb cleaner- or wd40 at the joints to note any rpm changes and try to narrow it down.

 

I had this problem after my Cam change. I needed to increase to idle until I could adjust the idle needle to make it richer.