Originally Posted by DENCOUCH
I loaned my vacuum gauge to my son as he is growing frustrated attempting to get his build tuned. He begged me to please drop by and help him figure out WTF was going on because the gauge needle was all over the map.
I installed the gauge, started the motor & he was correct. The needle flips back & forth from vacuum to pressure... almost spanning half of the dial.
Weird stuff! I also noted that one of the exhausts never gets hot, well, not like the other side. The air mixture screw has no effect either.
It is a twin cylinder Honda. (I know this is a car forum guys, but he did install a race cam & custom made forged pistons... besides, lotsa hotrodders have hot-bike experience too!)
I was thinking that perhaps one of the el-cheapo exhausts he is running may be clogged because of sloppy manufacturing (Chinese). That is my best guess, anyone want to weigh-in on this?
Do a leak down or compression test- it could have a bad head gasket.