TOPIC:

1) because I've been running my bike for most of this season without them with no problems or concerns !
2) With 3 other mods I've increased my mileage to 50+ mpg - consistently
3) because no one else has offered a simple solution.
4) these are not factory fresh engines any more and there's a need to think outside of the box !

Scotch,

Thank you for the rhyme and reason on this which is very interesting indeed.

I have always ran all my 1300's with the 3 small side diaphrams in place and operational, but what you say makes me think again.

One of my "To Do" jobs this winter is a full carb strip and rebuild, so after your reply I may well remove the 3 diaphrams and fit a sealing gasket on the 3 small covers as you suggest and see how it goes.

Thanks for sharing this information.

Pete F
UK

With the acknowledgement, I'll re-iterate the basics:
The only "documentation" I have are the fuel receipts/mileage. Started out simply "experimenting".
1) Started with the ign. timing. - retarded approx. 5 degrees.
2) Modified a set of pilot needles. "pointed" the tips in my drill-press with a crude angle-jig and "2000g' oil-stone. Initially got 4 the same. Had to work at the remaining 2 so that all six "Color-Tuned" at 2.25 turns +/- 1/8 turn.
3) Re-gapped standard NGK's from the G.M. coil recommended .045" TO .029"
4) Gutted the enrich. system.
Did these one at a time and noticed a cumulative increase in mileage with each "adjustment".
Spark plug condition? Outstanding !
In the end: 2 most recent and identical rides - 260k @ consistent 100KPH top speed. Shifted and rode conservatively. No perception whatsoever of any decrease in overall performance and no anomalies. 51+ MPG. Can now sync. to 9.5"hg.
One of those rides was with out my intake system, to determine it's benefit/liability. Had 10/15MPH head-winds for half the ride so the results were inconclusive. 49+ MPG.
For the truely "academic minded": '80A - 90,000K. (never been apart.) Esso Reg. Altitude 1200' +/- 200'. Temp.: 28-32c. Humidity 45%. 28 yr old DG. New pilot jets. New rear rubber with Nitrogen and "Beads".
All easy to do with perhaps the exception of the Pilot-Needles. They are not difficult to "point" but paitence and care is required to do them correctly. I commented about this mod. some time back. The most obvious benefit is with regard to "color-tuning". Now, with a 2.25 Turn +/- 1/8 turn range, the middle of the "Blue" range is definitive !
Difficulty rating: 2.5 out of 5 eggs !
It would be interesting to hear of others trying this, and seeing their results.

Very interesting Scotch, thanks for the information.

Just so I fully understand the "Gutted the Enrich Sytem" part correctly,

Remove the KZ type clean air recycle system (not present on the Euro Z1300 model).
Remove the 3 small enriching system diaprams and spings from the sides of each carb body.
Make gaskets for the 3 small covers before replacing.

Is that the procedure you followed ?

Pete F
UK

Yes, that's it ! The gasket seals the cover. Specifically: blocking-off the diaphragms vacuum port found in the left side of each carb.

Hi Scotch,

Thank you again for confirmation.

Could I also ask which tool you used or how you set your Ignition Timing at 5 degrees retarded ?

Pete F
UK