BMW Heads, porting, cams, suitability for big bores.

[In the shed]

ASBO was bought an 86mm forged crank the other day. The resulting financial shock made me put the old crank, rods and shortly other bits on ebay.

This new crank has made me question the whole parameters of my engine. It appears the existing pistons have had a gnats fanny skimmed off them and I don't really like the idea of whipping another 2mm off. I'd say that I'm probably going to get a set of H Beam rods and proper short 73.5mm pistons.

This brings attention to the head and the carb. A while ago, I decided I didn't want to hack the dash about for the weber box, but go the IDA route instead. I am now forced to look at the compression ratio of the head and it's going to be pushing it. I wondered whether it would be an idea to rip out the cam, head, carb, manifold, dizzy and sell them all as one thing and then BMW head it. The simple reason being that it would kill lots of birds with one stone. No hole in the bulkhead, no hole in the bonnet, sensible fueling and ignition, etc.

I think my old stuff would command quite strong money and if I'm spending a fortune on the bottom end, I might as well go the whole hog.

Quite clearly, a BMW K1100 head is designed for a 1100cc engine. This is not a 1460. I am aware that RS cams take things out a bit, but it may be an idea to take the ports out a bit.

This is a project which has been in the shed for years. It's been gradually creeping forward and something I have been amassing a pile of parts for over the years. It's not really urgent enough to go phoning anyone, but would merit a discussion, or any useful pointers.

The mini is relatively low priority and I'd buy a Sylva Striker over a KAD head. I'm a bit of a tinkerer and like to do my own work, where possible.

Stu

[Richspec]

I'm building a bmw head/engine up at the moment, took advantage of someones abandoned project and bought it all ready to assemble minus the odd few bits. Its not that cheap unless you can do a lot yourself and specialist components know how to charge if you go there for stuff!
Mines just a lowly 8v. I know a lad who has a turbo charged 16v which has seen 300bhp and another mate has been building one slowly over the past couple of years.

[Chalkie]

Turbo mini lads are the guys to ask about this convertion few are doing it

Matty over on there has took things whole step further

[In the shed]

I've re-joined TM and put a post there. Lost password.

We'll have to see what comes up.

[Oldskoolbaby]

Speaking from experience, I personally wouldn't go down the road of building a BMW twink up again then spending a small fortune working the head to meet my needs. They are a great conversions if you intend to do little to no work on the original head casting albeit whats needed to fit it. However, in my opinion, it makes no finacial sense when KAD offer a superior head and cam set up straight from the get go. Again, I'm not saying you can't get good results from them but its worth breaking down what you get pound for pound with the finished article.
I had the stock K1200rs head which was a pretty good alround setup with the better cams etc. Was night and day compared to the trusty 5 port anyway. 1460 with a stockish head and ports would make a stump puller of a motor I'd say.

[In the shed]

I wouldn't spend a fortune on the mini, because it is a David Vizard book wielding enthusiasts car. If it came to spending KAD head money, I'd be doing it on a Striker.

The 1200RS sounds like the weapon.

The car is merely for blasting around B roads in Cornwall and Devon.