Wan't start after partial cool down

[pplassm]

I have a 1978 XS650 Standard. It is completely stock.

Normally, it runs just fine. However, if I ride for only a few miles, approximately 10 minutes or so, and let the bike cool down for a few minutes, it will not start.

The only solution I have found is to let the bike cool for about 30 minutes or so, the bike starts with the enrichener. This situation is made worse in hot weather.

Anyone else have the same problem? Does this indicate the bike is too rich, or too lean?

Thanks!

Oh, that's "Won't", not "Wan't". D'oh!

 

[Classic]

What do your plugs read?

 

[5twins]

You may have a coil going or gone bad. Many times they act up when hot but work fine cold.

 

[xjwmx]

At various times mine would be like that, but it was just a matter of finding the exact right postion for the choke. But I've got continuous choke bs34s

 

[GreasyC]

you shouldn't need the choke unless it's cold out. I forget what mikuni's rule of thumb for that was but its something like 65 degrees and up it should start without the choke. 5twins is right too, bad electrical parts get worse with heat (resistance goes up with temperature). I had a corroded plug boot once that would fire when cold but start to miss after 20 minutes.

 

[TeeCat]

You may have a coil going or gone bad. Many times they act up when hot but work fine cold.

I think this is worth at least checking into, to be sure. When I first got my bike, I had weak coils masquerading as fuel delivery problems, and it gave me fits. As a weak coil gets hot in can indeed result in a no start or no run condition.

TC

 

[xjwmx]

^Maybe, but all that stuff would show at least some symptom while it was running.

I don't know about Mikuni and 65 degrees, but I just started mine first thing this "morning" 90 degrees outside and it wouldn't run perfectly without 1/4" of choke for a couple of minutes. And everything is perfectly okay. Now it might not be his problem, but it's a valid consideration

 

[pplassm]

Thanks for the suggestions. I will look int to electrical system, and I haven't checked the plugs.

It runs just fine, as long as I don't shut it off. It's only when the bike if halfway cooled down that it happens.

 

[pplassm]

Hmm. Plugs look nicely tan.

I will likely replace the carb jets with new brass.

 

[GreasyC]

90 degrees wow. Well if you live somewhere where it never really gets cold then it doesn't matter much. The idea is if you have it adjusted to need the choke when it's 90 degrees, how are you going to start it when it's 35? It only has so much range. My carbs are the older 38s but I almost never use the choke, it fires right up in normal weather.

 

[XSLeo]

Before you just start swapping jets around you might want to read the carb guide
Just swapping parts without knowing just how the swap effects things is just wasting time and money.
Leo