Carbs etc.

["Tom Brown" <tbrown@xxxxxxxxxxx>]

John:

I think you're entering a whole new world trying to put carbs on an oilhead.
Be prepared to replace the motronic completely with analog ignition etc.
All the fuel curves etc are going to be completely wrong.

As far as your fear that the throttle bodies need to be adjusted all the time,
well, that's just not true.    You need to adjust when you adjust valves
because changing the valve clearance affects the vacuum in the throttle bodies
just as it would in carbs.   When you synch, all you're really doing is
adjusting the length of one throttle cable so the vacuums match on both sides.
This doesn't take long and isn't needed that often.

Part of the reason these bikes seem so sensitive to synch is because they're
twin cylinder with large displacement, no balance shaft and the engine is used
as an integral part of the frame.   On any other bike, a setup like that would
shake the tar out of you.   These bikes are very smooth by comparison.   The
bit of vibration you do feel can be eliminated by careful tweaking, but it's
not likely to be any different with different carburation.

If you're just looking for more power, like for racing, this may be a good way
to go.  In racing, you're not concerned so much with low end torque,
smoothness at lower speeds, the ability to idle smoothly without stalling or
hunting etc.   Many of the fastest race bikes run like absolute crap at sane
speeds.    It's not a priority.

If this is your main street bike, my advice is to stick with the stock stuff
and maximize your enjoyment of it by eliminating the surge problem and keeping
it synched and tuned.    If it's more of a toy or science project for you,
well, go for it.   Who cares if it won't run?

To equate the motronic/throttle body system with Bing carburators of old is
not valid.   There is a bearing, especially on the right side throttle body
that can go out and cause the bikes not to synch well and make a little
rattling noise on the right side.    This can happen on high mileage bikes.
Just replace the throttle body or the bearing if you can find one and be done
with it.

These are great bikes the way they are.   Learn to get the most out of them
and you'll be pretty thrilled.

- -TB

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