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Discussion Starter · #1 ·
Hi all, first post here so if this is a repost please move to the right place.

I have a 1980 Honda CM400, was running beautifully, then I parked it for ~6days and when I started it again it refuses to idle. It is also has trouble turning over (electric start) it struggles, then turns over easy for a few strokes, struggles turns easy, and eventually starts. At full choke it idles for a little bit, and it will run if I give it enough throttle to keep it at 3000RPM. Both pipes get hot, but the left definitely heats up a lot slower then the right. If I rev it up to 5-7k RPM I get what sounds like a little backfire.

My first thought was plugged idle jet, so I took both jets out of both carbs, cleaned them (could see clearly through each), also replaced the inline fuel filter (hadn't been done in awhile so figured I should). Choke appears to be functioning fine, value timing is good, battery is good. Fairly new to working on a bike so really just not sure what steps to take next, any help/advice is greatly appreciated!!

Cheers,

Rob.
 

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What do your plugs look like? Are they the proper plugs? D8EA?

Edited the plug number
 

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New plugs would be a good step. Another possibility is a plugged/restricted passage in the carb which a quick cleaning won't fix. If you check the Fuel supply and carburetion section you can find lots of information on that.

Welcome to the group.

Got pictures?:p
 

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Have you checked your battery/charging system? If your battery is bad it can cause this condition.
TOOLS
May I add "load test the battery" not just put a meter on it.
 

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These models only depend on the alternator for power to the ignition, tools1. They will run just fine with no battery at all. So, new plugs and then carbs.
 

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You might drain the tank completely and add fresh fuel first. I've had a couple of instances where fuel went bad really fast.
 

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Discussion Starter · #8 ·
Thanks everybody for the suggestions. Worked late tonight but have all day tomorrow to do some work so will give it a shot and report back.

Here is a pic of her just for kicks:
Screen Shot 2015-06-19 at 8.12.10 PM.png
 

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Discussion Starter · #9 ·
So correct plus are in there D8EA, both have good spark. The left plug was black and wet with fuel, and the right is just black (looks like it was running rich, this may be from running it with full choke while diagnosing the problem).

from your suggestions this leads me to think left carb issue of some sort? any body have a good link on how to begin looking at that?
 

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You'll want to get some clean/new plugs in there. There is a sticky in the fuel section for the carbs.
 
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