Help...My 850 won't start!

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Sep 25, 2007
Hello gang, I have a 1969 Interstate with a rebuilt 1974 850 engine installed.
I have been tinkering around with it during the winter and it won't start. It already was temperamental starting anyway. I decide to put a SPARX 220 watt alternator on it to run the halogen and flashers at night. It also has a Eagle coil and it had a Boyer power box but I replace with SPARX 3 phase rectifier with the new alternator. It also has a 36 mm Mikuni. I drained the sump which had about a pint after 1 month sitting. I have been trying to gauge the amount of spark and believe I have weak spark...when I kick it with the plug against the fins it shows a slight white spark both sides? The battery is charged and reads 12.44 volts. I also tried a little starting fluid and got some backfires but no start. Tried choke on and off. Any Ideas or recommendations?
Are you running points or electronic ignition?

Have you checked the compression?

How about timing?
Are the plugs wet or dry? If they are dry, are you sure it is getting fuel? Since the bike sat for a while, the floats could be gummed up and not allowing enough fuel in the bowl. Since the bike tried to start on ether, I would look at the fuel delivery. For good measure I would also replace the plugs with new ones, so if they are fuel fouled it will take that out of the equation.

I have had similar issues with my own Mikuni's when the bike sits for several weeks or more. I'd take the carb apart and thoroughly clean it, paying particular attention to the rods the floats ride on and the float needle and seat.

I try to make sure to drain the float bowls if the bike will sit for any length of time.
Thanks Ron and Arch, sorry it took so long to reply...Ive been at work and just returned. Arch, I have points and I have tested the compression and its good. Can you tell me the best way to test the timing with the bike not running? Ron, I think you may be on the right track and I will clean my carburetor up. Can you tell me if I need a new float bowl gasket or can I reuse my gaskets? Thanks again guys and I'll keep you posted on my results.

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