FZ/MT-07 engine wanted

[50Joe 183]

Looking for a low mileage engine. Mine decided to implode at the WERA GNF 2 days ago.

[50Joe 183]

Found an engine and what caused my failure. #1 cylinder basically overheated and seized, etc due to being way too lean. I've learned this is a common problem with bikes that are raced and don't have a proper ECU flash. ECU programming from Yamaha has a 20% fueling difference between cylinders. MotoAmerica FZ/MT/R7 engine builders speculate this is for emissions. My bike had an early ECU flash from way back in 2016 or 2017 before this was known. Even today, not all ECU flashes are the same. So, choose wisely. I'll get a flash from a MotoAmerica race engine builder who is known to have engines that last.

[M. Hausknecht 361]

2 hours ago, 50Joe said:

Found an engine and what caused my failure. #1 cylinder basically overheated and seized, etc due to being way too lean. I've learned this is a common problem with bikes that are raced and don't have a proper ECU flash. ECU programming from Yamaha has a 20% fueling difference between cylinders. MotoAmerica FZ/MT/R7 engine builders speculate this is for emissions. My bike had an early ECU flash from way back in 2016 or 2017 before this was known. Even today, not all ECU flashes are the same. So, choose wisely. I'll get a flash from a MotoAmerica race engine builder who is known to have engines that last.

I discovered the disparity in fueling between the two cylinders in the course of tuning my 07 race bike early this year after destroying the #1 piston in a motor I didn't build.  Although I'm using an aRacer ecu, their base map seems to mirror the disparity between cylinders. It struck me as odd, inexplicable actually, so I eventually adjusted it out. You might think, I did initially, that if one cylinder were appreciably leaner than the other that it would be evident when examining the plugs, but it wasn't. That led me to conclude the stock plugs are a bit too hot, at least in a race motor, to provide a decent read. I then went one step colder with the plugs and began to  see a difference. The fact that many/most builders and tuners (and me, I'm afraid) use only a single WBO sensor just masks the problem. Anyone who uses a WBO in each downpipe while tuning would see the disparity in AFR between cylinders immediately.

There is, I think, a second element at play. I am aware that both the aRacer and the FTECU base ignition maps for the CP2 use a couple to several degrees more advance than the stock ignition maps. I suspect they add timing because it then allows them to claim, truthfully, that their tuning yields more power in a stock motor. My suspicion is that the extra advance, combined with the fairly low octane of MA-spec fuel (94.2) or premium pump gas (what I ran previously), combined in some cases with the significantly improved volumetric efficiency of a well-built motor, results in dangerously excessive ignition advance. So, what we got was too much heat in the #1 cylinder from a lean mixture and too much spark advance.

[50Joe 183]

Just now, M. Hausknecht said:

I discovered the disparity in fueling between the two cylinders in the course of tuning my 07 race bike early this year after destroying the #1 piston in a motor I didn't build.  Although I'm using an aRacer ecu, their base map seems to mirror the disparity between cylinders. It struck me as odd, inexplicable actually, so I eventually adjusted it out. You might think, I did initially, that if one cylinder were appreciably leaner than the other that it would be evident when examining the plugs, but it wasn't. That led me to conclude the stock plugs are a bit too hot, at least in a race motor, to provide a decent read. I then went one step colder with the plugs and began to  see a difference. The fact that many/most builders and tuners (and me, I'm afraid) use only a single WBO sensor just masks the problem. Anyone who uses a WBO in each downpipe while tuning would see the disparity in AFR between cylinders immediately.

There is, I think, a second element at play. I am aware that both the aRacer and the FTECU base ignition maps for the CP2 use a couple to several degrees more advance than the stock ignition maps. I suspect they add timing because it then allows them to claim, truthfully, that their tuning yields more power in a stock motor. My suspicion is that the extra advance, combined with the fairly low octane of MA-spec fuel (94.2) or premium pump gas (what I ran previously), combined in some cases with the significantly improved volumetric efficiency of a well-built motor, results in dangerously excessive ignition advance. So, what we got was too much heat in the #1 cylinder from a lean mixture and too much spark advance.

Everything you wrote is exactly what the MotoAmerica engine builder told me. I plan to race the engine stock with only Yosh race exhaust and JD Hord airbox. He said his flash would keep the OEM ignition advance which he recommends and overly riches both cylinders. Then adjust down the AFR in both cylinders using a PCV. He welds bungs in both header pipes so he can measure each cylinder independently. I want a most bullet proof motor as possible versus outright max power so this is the route I plan to take. It should be more cost effective too with less headache since I'll be using a known formula that has been raced on for a few years now. I think it's total BS that Yamaha programs the ECU from the factory like they do.