Yeah, that's some pretty bad reversion for cams with only 18° overlap. Not so easy to pull fuel from just the offending rpms with a carb.
You mat also be dumping more fuel with the needle than normal too if the needle has worn the needle jet oblong. Or is that new? If not, check to see if it's worn.

 

That's something I have not checked that close, is the orifice in the needle jet. The carb was listed as "cleaned and rebuilt" with about 30k miles on it, but I think it was mostly gaskets, and may the float needle. It's something I have not replaced, so it's probably the original one.

 

I looked at the videos and went back through the thread.

Did the bike run well before the cam change?

On the video, the blow back occurs on only one cylinder on both videos. The reversion didn't change. Look at it at youtube 1/2 speed so you get 1/4 speed on both and you'll see that they are pretty much the same. Look at fuel getting sucked out of the main passage. It flows twice to every blow back. I was thinking the pipe since the stock pipe is imbalance on the exhaust. It's not that.. I suspect that the difference in plug colors is another clue. I've seen them different but not that much.

While 15 psi difference between both cylinders could be OK, I'd suspect that cam timing is off. I know that it's a PITA to pull the stock exhaust on these things but I'd say it needs checking.

 

The bike did run well, yet it did have less pull than before the cam change. I think my mpg was 38-ish before the cam change.

Well the exhaust should come off easy. I think I've had it off 3-4 times in the last 3 years. Last time was about a month ago to replace gaskets and TORCA clamps that were probably original and threads were getting galled from all the disassembly. Hopefully this weekend I can open it up to check things out. I'll be the first to be humble about getting something incorrect because I know I can sometimes rush things if I feel hurried or have many interruptions. (And the cam chest is something to definitely NOT rush.)

Thanks for all the help and responses. I'll get some pictures of the inside so you can double check my work!

 

Max might be on to something but I would have expected more than a 15psi variance between cylinders if cams were a tooth off but I guess that would depend on the intake valve timing which is different from cam to cam. I know it's a bit of a PITA to check but if Max thinks it's worth checking, I would check it. If the cams are properly timed, we can move on to something else.

 

If you play with the calculators and get about a 8.54 to 1 cr, you get about 163 psi on a 30 degree intake close. 0 degree intake close gives you only 173 psi. 1 tooth works out to about 38 degree timing change. I'd say the front cam is advanced 1 tooth.

 

True, I always thought it was more in the neighborhood of 25-30 psi difference..

 

Well, I thought maybe it was my eyes, but I think I'm off a tooth.....

But I will take this if it's the solution to all the problems!!

 

Yep 1 tooth advanced front cam.


It will run a whole bunch better.

 

Good catch Max. Now Det can get the carb setup properly and, like Max says, it will run much better.