QuestionHi, I have a 1983 Honda CM250C belt drive that sat for 20 years with gas in it. I have totally cleaned and relined the tank, cleaned the carb and put in new gaskets and a float valve.
Here is a video of what it is doing now. It has black carbon on the plugs and smokes when starting.
http://www.facebook.com/video/video.php?v=1561594444676&ref=mf
can you help me?
AnswerLesa, I watched and listened to your video.
Did you disassemble the carburetor completely and clear all fuel and air passages?
http://www.cmsnl.com/honda-cm250c-custom-1983-us_model7282/partslist/E++1501.htm...
I see that it has primary and secondary main jets. You may have them reversed, if they can be interchanged. The #1 item surrounded by a [ ] box is the idle mixture screw. Leave the limiter cap off, so you can make adjustments to it.
If you didn't clean the air passages in the carburetor throat, the idle/main jet circuits are not getting enough air to emulsify the fuel being metered into the jets.
I think I am hearing mechanical noises that are either loose valves or loose camchain.
Valve lash should be set at .002" COLD engine, intake/exhaust on COMPRESSION STROKE when both valves are closed. Each cylinder takes turns, so one is on compression and the other one is on OVERLAP stroke when both valves are slightly opened. DO NOT ADJUST those valves. At no time, should the valves be looser than .002" Check them while slowly rotating the engine with the stator bolt on the end of the crankshaft. Compression check should show around 175 psi on both cylinders, throttle held wide open.
Try those things and let me know the outcome.
Bill Silver
