1977 Gs400 rejetting

[West]

A new question. On the GS400 there are aluminum spacers, about 9/16" thick, between the carb boots and the cylinders. In each of the spacers, there is a small dam, approx 1/4" high, along the bottom of the spacer, approx 1/8" thick , situated at the midpoint of the spacer. These dams change the profile through the spacers from a circle to a "D" shape, with the flat side down.

The intake ports in the head are circular where the spacers contact the head, as are the carbs outlets (of course).

So, basically, as far as I can tell, these little dams would do little more than add turbulence to the airflow as it passes the specers. My understanding of intake design is that you want as little turbulence as possible, pure laminar flow is the design goal.

So, why are they there? I know that D-shaped intake ports are one method used to achieve a more linear velocity profile across the ports (and therefore less velocity variation, promoting laminar flow) but these dams would hardly do that.

I have thought about grinding them down, so the spacer profile would match that of the carb outlet and the intake port, but of course hesitate to do that as the procedure would be irreversible without replacing the spacers.


Anyone care to comment?

Still in the jetting process, I am up to the 127.5's and still getting more power. The 122.5's were way too lean, plug chops showed that. I'm going to try 130's and 132.5's, (Keith was right in his first recommendation - of course) and based upon my earlier testing, I think the 132.5's are going to be spot on or a hair rich. The only problem I am having is an annoying little burble at low throttle, about 1/8th, get it in every gear as I hit the gas after a shift. I am not really attacking thet now, got to get the mains correct first.

I have a picture of the carb spacers

[img=http://img168.imageshack.us/img168/4922/hpim0344tz4.th.jpg]

Anybody got some thoughts on these? Another question related to the spacers - do the dams go on oriented at the top or the bottom? I have them at the bottom, as i think that is how they were originally.

[witweew]

pod runner

yeah, well there plenty of free podcasts or whatever on the internet that are supposedly "designed" for
workouts, but remember -- you get what you pay for -- the creators of these podcasts have to rely
on "free" music...... they can't license real hits, they could never afford to\\/ .... if you look
carefully at the playlists, you'll realize they are all either outdated techno from back in the 90's,
or they are really "underground" (i.e. terribly, terribly boring) tracks, with just a beat going
forever until u want to kill yourself -- ....

If you want something that's really going to get you motivated and keep you motivated...
I recommend the "Euro Club Hits" series -- it's on iTunes -- you can just search for it,
or try this link: [-o<

http://phobos.apple.com/WebObjects/MZSearch.woa/wa/advancedSearchResults?albumTerm=Euro+Club+Hits+Vol+