Cliff, all very interesting stuff and I am learning as I go
Going back to the throttles. The original K1200 bike head used the 38mm throttles that I intend to fit. The bore is the same as the bike engine, but the stroke is longer, giving me just over anothr 100cc resulting in the 1275cc. I am running the 34mm throttles from the K1100 bike engine at the moment. The way I see it is that if BMW though it wise to fit 38mm throttles on the K1200, that should be the way I go with this engine. after all, I spent a lot of time and effort to get the cylinder head and bores to line up as if it were the Bike engine
The ports in the head a standard and the same whether K100, K1100 or K1200, the heads are pretty much all the same, although the K1200 uses 5mm stem valves as oposed to the 6mm stems
Currently the cruse point is around 14% at 30mph and around 20% at 60mph. Maybe its just the throttle break points but that is the middle of the map, which leaves me little room to traverse to the rich load points and have enough of them at the top of the map. I would hope for the same throttle % that the larger throttles will provide more air but lower down the map, so I can move the lean spot down and away from the rich load points. Its going to be a suck it and see matter, excuse the puhn
I have the idle tuned for Lambda 1 and the fast idle set for 1.02, while I dont yet have the cat fitted, it will be going back on when I can get the link pipe welded up.. Everything above the 5000rpm mark in the cruse area is lambda 1, and blending from low rpm to the 5000rpm is smooth, as it is going from part throttle to full throttle, but i would like to drop the full throttle 0.86 lambda down a line or two. I have raised the compretion ration half a point from the standard 11:1, I run V power all the time and I have increased the part throttle ignition advance to 38 degrees with 30/ 32 at full throttle. we never managed to get the ignition map tuned due to issues unknown causing a retard of advance going into the engine compared to what was actualy in the map.
I dont think there will be much of a problem loosing some torque off the bottom of the map requiring more throttle input, the engine puts out over 100bhp at full throttle and the car only really needs 18bhp to keep it moving. so if by opening the throttle and leaning off i can get the torque back to the reuired level at a point in the map that is not too high up the map to affect the transition from part throttle lean to full throttle rich, I think there is some gains to be had in there some where.
One of the other reasons I went for firmware 1.1.44 was the better acceleration enrichments. Hopefully I can tune these to take into consideration the lean spot on the map.
This lean area is purely for cruse and nothing else. The engine revs to 8500rpm and is a bit of an animal at full throttle when it comes on can around 4000rpm
I am never going to get the results manufacturers do, I just cant afford the dyno time
so a comprimise will always be on the front foot
No harm in trying, and is easy to get back to a lambda 1 map as long as there is no damage to the engine as a result
