If it was 180 out, it wouldn't be running.I think you just have a tuning issue.You have a very restrictive exhaust silencer on there, which is about like a potato in the pipe. If it ran well with the open pipe, then it's going to run like shit with that muffler on it.Try unscrewing your air bleed screw a half turn, and see if that helps it.I think you're just too rich with that muffler on it.
That gives me more peace of mind. Thanks.Is the idle mixture purely controlled by the two screws on the outside and not any jets?
If it dies when you open the throttle quickly, that is indicative of it being a big, long stroke single. At low engine speeds a quick blip of the throttle will drastically change engine vacuum, but there isn't enough air velocity through the carb for the carb to work. Gas won't be picked up through the jets so it runs lean and stalls. Learning to roll the throttle on will eliminate most of this. This feature is why car carbs had an accelerator pump to pump in more fuel at low engine speed/large throttle openings. You can tune some of it out, but eliminating it requires an accelerator pump or jetting it so rich that you almost instantly foul plugs. When properly jetted you will never notice this issue with proper throttle technique.
A larger carb will make things worse if we are speaking of the engine dieing with quick blips of the throttle.That's one reason small carburetors are often put on street bikes where fussy engines aren't tolerated by the owners.
Advanced the timing and it runs better. Drove it up and down the street and it had decent power and throttle response. Still needs some tuning though. Runs rougher than I'd like.https://www.youtube.com/watch?v=FcRd6lkCCt8&feature=youtube_gdata_playerHow do I more precisely set the timing? I'm lost without timing marks.
Yes, it will take quite a number of miles before those rings are fully bedded-in.The basic sealing gets done early, but the rest of it takes quite a few miles.Idling won't do it. You need to load the rings up with some acceleration and deceleration with some real road riding. You don't have to rev it way up or be hard on it. Just give it some loading on some hills and stuff, at moderate speeds.That will help. You are probably running on lower compression than you expected, until the rings seat better.
A word of advice about the bottom end.You need very good bearings from a known top brand bearing company. OEM bearings really are not up to the grade.When you get the crank, you cannot assume that it is trued. Even if it was trued at one time, that is no guarantee that it will arrive at your house in trued condition. Shipping often knocks them out of true. It would be VERY advisable to use dial-indicators and v-blocks or a lathe to check that it is under .002" run-out total. Next, if you plan to build this bike beyond stock at all, you need to address the con-rod problem when you do the bottom end rebuild. The con-rod in the 500 is generally not best-suited for handling higher power or more rpms.My usual advice is that if you are going to go through all that work of a bottom-end rebuild, then build it up as strong as you can, and do it once, so you don't have to go in there again for a long time.