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Discussion Starter #1
I'm new to Hondas so I don't even know if this is an issue. Engine quits running in hot weather. No mechanical or ignition problems. Fuel in the tank. Pump works, lines and carbs clean.

You stop, engine cools, starts and runs fine.

Some bikes (in this heat) develop vapor lock--fuel vaporizes from heat before it gets where it has to be.

No, I don't have a solution, other than a cool water spray on fuel lines and carbs. If you run into this, at least you have the peace of mind knowing what it can be.

-john (Lakota)
 
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Vapor lock is rare indeed on these bikes. They're liquid cooled, so a lot of the heat gets dissipated elsewhere before it builds up between the cylinders and cooks the carb. They also have rubber fuel lines, and the filter and pump are below the seat, so they're under the heat source. I can't say I've ever heard of vapor lock on a Shadow. (Of course, there's a first for everything!)

How does the engine quit on the heat? Does it slowly lose power and then konk out or is it like someone flipped a switch and it just stops?

Next time it quits on you, pull a spark plug and verify that you have spark. I'd be more willing to bet that you have an electrical component that fails in the heat.

--Justin
 

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I feel your frustration.

I’m still having that issue on my 1985 1100 and this only happens when it is extremely hot out. I thought I was out of the woods as I have been riding it the last week, around town after work with no issues; however, last night in the blazing heat I got 17 miles and it stopped. I was starting from a stop, gave it gas, got the chug, chug, spit, cough, I’m done, and then dies. When you try to start it back up at that point it acts like it will, but it won’t.

After about 25 minutes it fires back up, back and I’m on the road home all the way without issue. Course on the way home the sun had gone down and the temp had dropped 10 degrees. I’m stumped at this point.

When it died I popped the hatch to the gas tank and tried to start it to see if it was a vacuum/vent issue, but still no dice. It would only fire back up after it cooled down.

http://www.hondashadow.net/forum/72-technical-discussion/110430-not-sure-what-going-my-1985-1100-a.html
 

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Discussion Starter #4
Just thought I'd mention vapor lock as a potential culprit in those frustrating cases when you can't think of anything else.

When it happens, engine will just stop running and will not start when hot.
Engine cools, engine starts, perhaps your fuel is vaporized. It may be other problems, certainly possible electrical, but it's one issue you should have on your checklist so you can rule it out. It can be really frustrating. If the temp drops, and your bike runs fine, your fuel was probably the issue. Sometimes the mix the oil companies are selling is a a little off for really hot temps experienced by bikers.

I just really hate it when I have a problem and can think of no reason for it.

Gonna try to resize my bike's photo so as not to annoy anyone . It's a crappy photo anyhow, and when I have time I'll take a better one.
 

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I LOVE the colors on your bike, Lakota :)
 

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I suggested to check for spark because I've seen a lot of these bikes have a faulty pulse generator. The pulse generator is a coil of wire that's thinner than a hair. Sometimes the heat and vibration (and perhaps a manufacturing defect) causes this coil to work perfectly until it gets hot, then the wire expands and the coil quits. When it cools, the wire contracts and connects again, making everything work as it should.

Check for spark to be sure this isn't your problem!

--Justin
 
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