Tuning my DR750s on Chrome

[Chris@Rvengeperformance]

Any input:



Not the worse plugs I've seen. A little lean maybe, but I have read alcohol reads differently. The ground strap doesn't seem consistent to me.

These are the rear 3. Again no plug damage or detonation flakes though. No oil indicating a broken piston or anything like that.

The rear turbo spins freely and tight. Hopefully they will just need a good cleaning and maybe fresh bearings.

[J. Fast]

Center plug is spot on... The outside two are rich. Looks like you have some unbalanced combustion events in the chamber. You want that chalked look half moon to the first thread and you should see a blue transition line on the strap at about 22 degrees off the base.

I don't think ignition events had anything to do with the failure. Is it possible your oil was thinned out from over fueling?

[TurboSinceBirth]

What about a bent rod from the torque? It's doubtful since I would think the ringlands should have broken first. The stock rods can't take too much of a beating from a lot of knock though. I guess you'll know more once you tear into it.

[Chris@Rvengeperformance]

Center plug is spot on... The outside two are rich. Looks like you have some unbalanced combustion events in the chamber. You want that chalked look half moon to the first thread and you should see a blue transition line on the strap at about 22 degrees off the base.

I don't think ignition events had anything to do with the failure. Is it possible your oil was thinned out from over fueling?

Thanks for the input. I'm sure the misfires I was running into during high boost was causing some unbalanced combustion as you put it.

As I was tuning yesterday I did pull out some fuel in places, but the WOT was never under about 11.2 anywhere. Idle and cruise were close to stoic.

The oil doesn't "seem" thin, but I'm sure that doesn't mean a whole lot, but it did still have the same oil pressure it has had since I started.

The fronts look more like the center one. I'm not sure what tune to break the new motor in on then. The one yesterday that was around 11.5 or the one today closer to 12.0 that it blew up on, lol. I guess I could take the tune from yesterday and just lean it out a tenth and go from there.

[Chris@Rvengeperformance]

What about a bent rod from the torque? It's doubtful since I would think the ringlands should have broken first. The stock rods can't take too much of a beating from a lot of knock though. I guess you'll know more once you tear into it.

It never really knocked until today when the sensor was just picking up rod knock. So far I'm going to have to go along with pushing the torque close to the limit and hitting those misfires yesterday probably beat up the big end of the rods. The misfire was at 4000, where it makes 450 torque. Hell, maybe the bearings I put in just were not a good fit, I was really on the fence about putting the stock ones back in.

I'm just trying to avoid this again. If I beat up one of ray's engines I will be f*cked!

[Ninja Performance]

Plugs for AFR are read down on the ceramic nose where it starts, down in the plug. You need a bright pinpoint light to actually see down there. There should be a thin tan/beige ring at the bottom. The wider and darker (towards black) it gets the richer it is. This is not something you can see by just looking at the outside nose of the plug.

The Strap will tell you if the heat range of the plug is right. If it changed color in the middle of the strap, it is the proper heat range.

therefore, this pic of the plugs can not tell us about the afr. Look down into the plug.

-Chris

[Ninja Performance]

Taking off the threaded metal part of the spark plug will allow you to see what I am referring to. Here is a pic. See the thin tan ring? This engine was running spot on. Now, if that ring gets too thin or is no ring of any color that is too lean. Black would be rich. And even a tan ring that is thick is leaning towards rich.



-Chris

[Chris@Rvengeperformance]

Yes I did look down the plug earlier. There is a ring just about one to 2 mm off the bottom of the porcelin. It is a light to medium gray and is maybe the width of a pencil led. I can cut off the threads if you want to see it.

[Chris@Rvengeperformance]

k, I'll cut the metal part out of the way and post.

[vr4tune]

Taking off the threaded metal part of the spark plug will allow you to see what I am referring to. Here is a pic. See the thin tan ring? This engine was running spot on. Now, if that ring gets too thin or is no ring of any color that is too lean. Black would be rich. And even a tan ring that is thick is leaning towards rich.



-Chris

This was the method I was taught. It is nice and simple to understand.