I am thinking there is a problem, Rob. >Who gapped the plugs?< If there is not black smoke out the exhaust, then the gap is not correct or the electronic ignition module output is down on voltage.

 

Consider changing your premix ratio from 32:1 to 40:1. Worked for me.

 

I know Rob has a KLX, but that scenario came to mind from the old days of owning some pretty nice 2-strokes. I've joked here about fouling 3 plugs on a 70's Husky 2-stroke Auto back in the day after forgetting to pull out an athletic sock stuffed in the rubber boot of the airbox during a filter service.

 

Rob, what does the plug look like that you remove? Is it wet with fuel?
It's pretty unusual that it fouls plugs unless the mixture is WAY off or there is a really weak spark. It does take things to be pretty close to correct to get the cold-start sequence to work successfully.

Is the choke circuit working?
Black smoke at ANY time?

The symptom of the underlying problem is a fouled plug and there must be a reason for that

 

Yes, I was thinking a pic of one of the plugs might be helpful, but if it is gas fouled, the gas evaporates so quickly that there may be little to see. On our 2-strokes when we fouled plugs, there was always a lot of oil residue left behind as evidence, even if the gas was pretty much evaporated.

 

See, I've been thinking weak spark too. Since I have that hesitation that came back even after grounding the regulator (it fixed it before the 351), I really wonder if either my coil or regulator are not up to snuff.

No black smoke ever... the choke is fine; remember this has happened with two different carburetors -- stock and a BB TM34.

Rob

 

What if it sits for less than a month? Does it start better?

Next time you get done riding it, make sure it restarts easily while it's still hot to rule out it getting carboned up while riding it. And just for the heck of it, pull the plug when it's going to sit for a long time, then put it back in next time you want to ride and see how it starts.

Have you been using the same brand gas with both carbs?

What plug are you using?

 

It starts fine as long as it doesn't sit more than about a month. It'll start up pretty easily.
It's never had problem restarting when hot.

Gas is the same... the same basic Oregon 87 octane crap gas we have up here.

The plugs are NGK CR8E's, same thing that came in it.

Rob

 

I'd go through every connection and ground I could find and get access to. It's not a waste of time, consider it preventive maintenance. Grounds are a source of problems, often overlooked.

I have just recently found 2 connection problems on 2 separate vehicles, even though they looked fine, it has solved issues that I hadn't been able to trace. Nobody more surprised than me to find the problems have disappeared on both vehicles and the connection didn't appear to be bad.

In your case it's not the plugs, probably not the gas, although a month sitting is running some risk. Do you shut the gas off and run the bowl dry before parking it for a month?

 

Rob, is your KACR still attached and functioning?