Tuning...

[Anders Dinsen]

I've learnt a few things in the last couple of weeks:

- The strange sound I had in cylinder 2 (from the left) was not strange, but just the inlet pulses. Cylinder 1 had a leak in the vacuum takeoff to the brake booster and gave the same sound when I blocked that leak. The other carb was just out of syncronisation. I have fitted a new (used) booster and refitted the pipework now, and I'll verify it next time I do some tuning.

- 45F8 idle jets are too lean, and I now use 55F8's. Idle screws are quite far back because of that (7/8'th of a turn from seated), but progression is fine, so that's good.

- 35 acceleration pump jets are too small, especially with the 40 bleed. I'm going up two steps to 45 and will try a zero-bleed to see if it improves things.

- Emulsion tubes are okay for now (no flat spots), but the engine is rough and is not producing full power. I think it's too rich, so I've ordered 140 and 145 main jets. Going up in accel pump jets means that the air corrector jets should also be increased, so I have also ordered a set of 190's and one of 200's. That should give me a few combinations to play with!

- I have finally settled on a solution for an airbox: It will be welded in mild steel plate. That is just the easiest and best way to do it. There has been a few dBilas airboxes in cast aluminium on eBay lately, but they always end above 100 €, and will require a good deal of modification to fit.

- I will try to correct the misalignment problem between the carbs by filing a bit of material off the studs so the carbs can be twisted in place. I will fit a heavy aluminium bracket between the carbs on the inlet side (inside the airbox) which will then lock them in position. The bracket will also be useful for attaching a support rod to the engine block.

Progress is slow due to lack of time and postage times from the UK (where I get the jets from). One air mail letter took 10 days to arrive! A pidgeon could have done it in half, I would think?

I have ordered a set of ram tubes now in 39 mm length. I can't use them with the K&N filters, though, so they will have to wait until I get the airbox finished.

That's all for now!