New 400 Engine Built-Headers Turn Red

[skatrdude20]

Alright guys here it goes, I just built a 440 engine from scratch. I basically built the whole thing bottom end and all. I finally got it in my bike, and got the wiring all hooked up and don`t have an exhaust system yet, so just to start it and make sure it runs I slapped my stock header on, no muffler. Anyways, after about 2-3 minutes, the headers get GLOWING RED hot. Any ideas as to what causes this.

[Colby@C&DRacing]

No muffler causes this air is allowed futher down the head pipe which causes unburnt fuel to light off and increase exhaust gas temp

[skatrdude20]

So what your saying is slap on the muffler to the headers and see what happens, my dad said he thinks maybe its the timing, maybe its retarded a bit, but I`m pretty sure I had it right on.

[GPracer2500]

Sounds like poor jetting combined with no airflow over the headers.

[chad502ex]

lean pilot jet or an air leak as C&D suggest.... I'd lean to improper jetting- bump up the pilot jet.


good luck.

[skatrdude20]

Alright, today Im gonna go buy some larger jets. I read in this thread on here about the 450r carb that guys are running anywhere from 170 up. And thats with less mods then mine. I took mine apart and my mane was like 118. And then my pilot was 48, thinking Im gonna go to like 180 and 50.?