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Discussion Starter · #1 ·
Hey guys,
So to make a long story short I did a full rebuild of my 74 cb200 for the most part, including full top end , all electrical, etc. i then had a very reputable shop double check my work because Despite the rebuild it wasn’t running right, after a few modifications they got it running perfectly and delivered it to me. I then let it sit in the garage for probably 3-4 months during winter and went to start it up and it fires right up, but its only the left cylinder. Bike will ride and everything but right cylinder isn’t firing. So my question before I bring it back to these guys who are super busy, is there something simple that could give it this problem? Today I undid the air filter made sure slide was moving properly, fired it up and both cylinders ran. I took it for a spin and all was well! Then right cylinder cut again. Could it be as simple as not having enough gas in the tank?! Any suggestions would be awesome!
 

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When the one side cuts out you could try opening the drain screw on the respective carb and see if its getting fuel on that side.

If no gas your float is probably sticking after sitting in degrading gas for 3 months and needs a cleaning.

Otherwise probably electrical, someone else should be able to tell you what exactly to check
 

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I'll second charging the battery. If that doesn't do it, check to see if the carbs are gummed up.
 

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Discussion Starter · #5 ·
Thank you guys! I will do these things today. However the battery was on a tender all winter. So I couldn’t see it being that.
 

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Discussion Starter · #6 ·
Welp,

I charged battery again, switched plug leads, and pulled out drain screw on carb to see if it was getting gas and all 3 things changed nothing!
 

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Discussion Starter · #7 ·
Turns out it is a bad ignition coil. I have an aftermarket one so no surprise. Does anyone know if they make an electronic ignition for the cb200?
 

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Discussion Starter · #9 ·
If swapping the leads from left to right didn't move the non fire side why do you think the coils bad? Even if the coil had an internal short it should follow that the non fire side would swap when you swap the leads. Can you please post a pic of the coil, and spark plugs
That is a valid point that I didn’t think about when talking with the shop owner. But I brought him the bike and he test drove it and it turned out that like clockwork if the bike was left to cool down it would fire both cylinders fine, but the moment it was heating up and pushed harder the issue would come up and right cylinder would die out. Immediately he said it’s either my condenser or the ignition coil. And my condenser is brand new genuine Honda.
 

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Discussion Starter · #12 ·
The wasted spark set up on the smaller twins means there's no timing issues with swapping the leads ( it's a 15 second job) and easily confirms that it's an ignition issue.
The twin fire coils usually either fail or work they're not usually heat dependant
Now Im kind of stumped. Because I totally agree with you on that. I swapped them over myself and nothing changed. It is an aftermarket cheapo ignition setup so I feel like could easily be something odd wrong with it.
 

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Discussion Starter · #14 ·
So with the leads swapped does the same cylinder die when hot or has the issue swapped sides?
I never actually rode it after that because Initially same cylinder was out. Doesn’t appear that the issue followed leads. But both sides were getting fuel and carbs are clean and balanced. So the issue lies within the ignition, and with a brand new condenser, I want to say its ignition coil.

The mechanic just told me to get an electronic ignition but if those use same coil, i dont see how that could help issue?
 

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If the issue doesn't swap with the leads it's 99% not an issue with the coil, if the points are working fine for one cylinder then they're already working for the other. So an electronic ignition isn't going to fix anything ( once you've got it running on both side figure out if you want something other than points.
Id be looking at a slow fulling carb bowl next .run it till it's warm and one side cuts out. Then kill the engine switch off the fuel tap at the tank and pop the fuel bowls carefully off the bottom of the carbs and see if they have the same amount of fuel in each
 

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Discussion Starter · #16 ·
If the issue doesn't swap with the leads it's 99% not an issue with the coil, if the points are working fine for one cylinder then they're already working for the other. So an electronic ignition isn't going to fix anything ( once you've got it running on both side figure out if you want something other than points.
Id be looking at a slow fulling carb bowl next .run it till it's warm and one side cuts out. Then kill the engine switch off the fuel tap at the tank and pop the fuel bowls carefully off the bottom of the carbs and see if they have the same amount of fuel in each
That was exactly what I was thinking initially. Because if I let it sit it would run, then after riding it stopped. As if the fuel cant keep up.
 

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Sounds very similar to my bike, when I was having problems with the float valves sticking. Aftermarket parts, would either stick closed, giving the symptoms you describe, or stick open and flood petrol everywhere. Float levels were set correctly. Mixing and matching aftermarket and OEM parts solved the problem for me. Keyster needles and Keihin seats, if I remember correctly. Tolerances were just too tight on the Keyster float valve seats.

Electronic ignition certainly isn't a universal panacea for sparking problems, it's just one less routine service item to bother about, in line with all modern bikes. I would not have confidence in that workshop ..
 

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Discussion Starter · #18 ·
Sounds very similar to my bike, when I was having problems with the float valves sticking. Aftermarket parts, would either stick closed, giving the symptoms you describe, or stick open and flood petrol everywhere. Float levels were set correctly. Mixing and matching aftermarket and OEM parts solved the problem for me. Keyster needles and Keihin seats, if I remember correctly. Tolerances were just too tight on the Keyster float valve seats.

Electronic ignition certainly isn't a universal panacea for sparking problems, it's just one less routine service item to bother about, in line with all modern bikes. I would not have confidence in that workshop ..
Im surprised that worked out for you! But in all fairness to the shop, they are absolutely swamped now that its spring time here, so his diagnosis was literally based off me bringing him the bike and him taking it for a ride. I could tell he was in a rush, and no other diagnostics were performed.
 

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Discussion Starter · #20 ·
Do you have the bike now ? Or is it at the shop? There are plenty of tests you can do to diagnose what's actually wrong ( without tools) even if you take it to the shop to do the work
I limped it to the shop, and didn’t want to ride it back home so I left it with them. I wish I hadn’t knowing the tests I could do.
 
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