I would try swapping the injectors at this point. I still don't like those iridium's in the big twins, I think they run hotter. You need a fresh set of plugs to see what's going on any way. I almost got a fuel ratio gage for my bike but figured I'd be constantly watching it and changeing tune. Glad I got a good Dyno tuner and done with it. I small flex light to look inside plug hole will till you if melting piston. Your smoked piston didn't show signs of the piston melting from the top though. Was the piston oilers checked before the second rebuild?

 

Have your tuner, preferebly while you are present run some tests and show you some graphs. 20,40,60,80 and 100% throttle runs, the step tests , with 250 rpm increments, so the afr can be confirmed. There also may be serious timing issues between the 2 cylinders, what do timing/igntion changes look like in the map? It is an advanced map correct? Each cyliner mapped for fuel and ignition individually? This is info that will help to identify your issue.
m

 

Also loaded cruise runs at 55~80 mph at 10 15 and 20% throttle with 5-10% load on the eddy brake.
m

 

You sure the oil squirter is working on the rear cylinder also?

 

+1 on swapping injectors. Sounds like a quick way to either confirm or rule out an issue with the read injector.

I'm not familiar with the MM set up. Are the injectors interchangeable?

Looks like the AFR kits vary widely in price and features.

Garrman

 

Yes you can swap injectors. I have spares if you find it's bad.

 

That's a good thought regarding swapping injectors. I'll give that a shot this weekend.

I agree that it wasn't a lean condition that caused the demise of my 1st piston. There's no way to know what it was, but S & S believed there was a high enough probability of product failure to send a new big bore kit so there's that.

My suspicion is that when the dyno tuner was doing red-line dyno pulls on that fresh motor, the cylinders were too hot to take it and the galling process starter there.

But I have always had a nagging suspicion that this is an oiling issue - that the piston oilers arent doing there job. I mentioned this as a concern to my builder for Round Two, and he said he'd pull the front oiler and check it before re-assembly, which I assume he did. I'll check and see.

You're not the first person to mention those plugs, so this weekend I'll also install a new set. I bumped the PCIII by 10% across the board with the three physical buttons and took it for a careful ride. Rear cylinder temps were down to the 325 range.

 

For now, I'm going to install AFR gauges with data logging capability so that I don't have to rely on anyone to tell me my AFRs. Once the engine is broken in per S & S instructions, then another round on the dyno might be in the cards. I realize this wont address timing issues, but at least it will help me eliminate mixture as the cause of my woes. If mixture isn't the issue, then I'll look further at timing.

Yep, doing it.

No, I'm not sure. The builder swears he checked all oil passages during the original build and re-checked the front squirter when he put in the new pistons and cylinders.

Agreed, and cxbullet says the injectors can be swapped. Doing that this weekend. And yes, prices vary widely, and I'll be buying from the higher end because I want data logging abilities, not just gauges.

Thanks xc, I appreciate that. I'll do a little research on bench testing the injectors as well, and do that before swapping them.

 

If you get the afr gage that your Talkin about you can tune it yourself and won't need a dyno. Just have to let out on clutch when let off the gas or it will mess up the numbers in your log I heard on here. May take a while to get it tuned yourself (learning curve), is the reason I didn't get one. Yes you can tune both cylinders on the MM system with the pc3, both timing and fuel. Also there is a accelerator pump option on the pc3, you should turn that on and set it. Makes a big difference on response and will help cool it when u twist the grip.