Re: KLR You Experienced? Not really.
After pulling off the carb and completely disassembling it, the only smoking gun I could find was a tear in the air cut-off diaphragm (exactly as cxman suggested as a cause). Some have suggested that the choke plunger may not have been opening/closing properly but after careful inspection I could rule that out - works fine. The jets are all stock sizes, as is the needle. Mixture screw set at 1½ turns out.
I got hold of another diaphragm, rebuilt the carb, checked the air filter was in good shape, installed a new plug and waited for the rain to stop.
Ok, please ignore everything I've ever written about Wide Open Throttle. Any diagnosis I've made, smoke I've seen pouring out the exhaust etc was made at WOT but with the bike in neutral and the engine not under load. WOT needs to be done in gear for - depending on who you ask - a mile or three. Which, it turns out, is quite a fucking thing.
Grabbed a bunch of tools I'd need, headed out to a stretch of road I figured was long enough and hopefully quiet enough on Easter Sunday, and had at it. This thing absolutely hauls ass. WOT for three miles on this bike I swear made me ten years younger. At least. Quite the eye opener.
Pulled the clutch at the end of the run, killed the engine and coasted to a gas station where I pulled the plug. Here's the scoop -
Light grey whatnot. From the diagnostic plug charts I've found online, I'm looking for a coffee colour, but light grey is pretty much on the money too, right?
The weird thing is that the bike still starts with no choke at all, even when cold. It literally leaps into life. Like there's a pool of gas in the cylinder, patiently waiting for the ignition. I know the choke is operating properly, and the main jet has nothing to do with start up. Pilot jet? Needle or needle jet? All those things are stock at the moment. The stock needle is not adjustable (I could shim it of course) but the DynoJet needle I have is adjustable.
The bike runs like a champ. In fact my man Brian who's worked on these things for thirty years says it's the best pulling and strongest KLR he's ever ridden. Would love to dial in the carb a little better at idle, but for keeping me young this thing comes up aces.