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Discussion Starter · #1 ·
I'm looking for new ignition coils for 1968 CB450 Black Bomber. Should I try and replace with new aftermarket? Are any available?

Or should I try and find used? I would think that's not a great idea since it will be difficult to tell if they're in good condition.

Thanks
 

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Sensei
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We've had good results using the Yamaha 650 coils (also available from Mike's XS)
 

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Go to http://www.mikesxs.com and buy a couple of the XS650 coils, they work fine and are quite affordable.

EDIT: Steve beat me to it :lol: ....but if you factor in the time zone, I beat him by about 16 hours :cool:
 

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Discussion Starter · #4 ·
Thanks guys. You are fast!

I wasn't sure his stuff is compatible. I'll order them and let everyone know how they work.
 

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Discussion Starter · #5 ·
Before I bought the new coils I brought the bike to an auto guy who could test the spark quality both hot and cold. Good spark... hmmm...

He's had experience with float needle valves not working so well which causes the cylinder to run rich. We clamped of the gas line to the poor running cylinder while it was running. All of the sudden, no more back firing. No more bogging down. No more running too rich.

Picked up a carb kit that includes new float needle valves. Installing today.

The carb kits have main jets at 130 but the carbs in the bike are 125. The idle jet in the kit is 38 but the current ones are 40.

Any experience with anyone changing main and idle jets? Or should I just clean them up and put the old ones back in?

My bike is 1968 CB450K0 4 speed with Keihin carbs.

Thanks
 

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Discussion Starter · #6 ·
Bad float needle valves were indeed the problem. Because they would no longer seal well, they allowed too much fuel into the floats and caused the cylinder to run rich. It gradually got worse as the bike ran more. Eventually it would bog down so much it wouldn't idle.

Here are a couple pictures of the bad float valves. Note the wear rings on the cones and one tip is missing.
 

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Discussion Starter · #7 ·
Bad float needle valves were indeed the problem. Because they would no longer seal well, they allowed too much fuel into the floats and caused the cylinder to run rich. It gradually got worse as the bike ran more. Eventually it would bog down so much it wouldn't idle.

Here are a couple pictures of the bad float valves. Note the wear rings on the cones and one tip is missing.
 

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