Wednesday, 27 April 2016

Everyday TR1 - vacuum ports

One of the (very few) let downs with the VM38-conversion on the Everyday-TR1 is the fact, that I had to sacrifice the original inlet manifolds with their vacuum ports. This in turns meant that I was (up to now) only able to sync the carbs the oldskool-way with a drill under the slide and adjusting the cables to suit. This did indeed work quite well, but after recently adjusting the carbs on a mate's BMW 2002 (without) and especially a Guzzi V7-700 (with vacuum ports), I decided that vacuum ports are actually a must have.

The task itself is nothing to write home about:

1) remove the carbs and put the cylinder you're working on TDC, to make sure the inlet valve is closed and stuff some rag (or paper towel) into the inlet.

 2) punch-mark a suitable spot on the head
 3) go at it with mad force (and in my case a 5.5mm drill)
 4) I used some 6mm o.d. stainless tube, which does fit snuggly with some persuasion (i.e. a big hammer and a drift)
 5) I then followed the Guzzi-Manual for adjusting the carbs and set the idle screws with the gauges hooked up to have both cylinders idle at EXACTLY the same speed. So far I only did this by ear and I have to pat on my own back - I was mighty close. Yet still, the idle is now without any popping or farting.
 6) Next step was to adjust the cables to be in perfect sync by turning out the throttle cable adjuster on the throttle housing until the revs lifted slightly, meaning that the cable lifted at least one slide off the idle adjuster, which is just a positive stop for the slide in the carb body anyway. From then onwards it took some fiddling and fettling until I got both carbs right.

Conclusion: It did make quite a difference so far. Mileage has improved notably and I found out that as soon as both cylinders are working as they should, my pilot jets proofed to be too big.

Things I did modify afterwards: I pulled out the vacuum tubes once more and countersounk the holes a bit and then filled the groove with epoxy to improve the seal on the rear cylinder. When the bike is really, really hot I am under the impression that it sucks in some air on the rear cylinder. Nothing dramatic, just a little mod to improve stuff even further.

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