Hey gang
After w-a-y too much work, rework and re-re-work, I think it's safe to say the 750 K2 is nearly finished. Hooray. I've just swapped the head for that of a K3/4 which is much smarter than the one that was on there, and it fires up and runs very well. With a list as long as your arm of new parts, vapour blasting and rebuild work, it's now lookin' pretty good. It's even quite quiet, which I'm sure has something to do with new chains and bearings throughout.
Anyways, one remaining thing I've never been able to sort out is the carbs. What I mean by that is that when it's running at idle, either the engine is struggling to stay ticking over or it's racing - there's no middle ground. It's almost as though the thread on the idle screw is too coarse, because no matter where it's adjusted to, the idle's either way too low, or far too high. Off idle (i.e. under power) it's fine - and very responsive - but calm idle is proving elusive.
The carbs have been entirely stripped out, vapour blasted, ultrasonically cleaned and all of the jets and other internals have been replaced with new bits. I've also synched them and made sure the all the linkages/gates (inc. choke) are matched to eachother. And yes, the cables are free and have slack in them. So they now look lovely (almost as good as a set of SL350 carbs I've just redone); shame they don't seem to be controllable.
Just in case you were wondering, this is pretty much what I start with:
(http://farm7.static.flickr.com/6025/5961861856_8df8c934fb_z.jpg)
. . . and once I've soldered up the holes in the floats (!) and overhauled them, the carbs end up looking like this:
(http://farm7.static.flickr.com/6140/5961862402_9cdebaba19_z.jpg)
But back to the 750 carbs, I'm trying to work out whether the idle I'm stuck with is how the 750's are generally, or whether this is something particular to mine - and if it is mine, why?
What do we think?