I currently have a Gunson Gastester winging it's way to me to tweak my fueling... I shall give a report once done on the off chance it helps someone else I was looking at a Gunson colortune but couldn't find them in stock and one place I use has had them on order for 5 months...
Be interested in how you get on with it. I tried using one of the older analogue ones and it drove me nuts!
I've got one of the digital versions and the results can vary a bit if the probe's not sitting right in the test port so you do need to take a few readings and get an average but on the whole does a reasonable job. Also got a colourtune, but not used for many years as it's not really that user friendly and wouldn't even be usable on some engines (such as a 916) due to the depth that the plugs sits in the head and the small bore of the plug access hole.
I Read somewhere that someone fitted 1/4 brass air fittings to the headers little plugged hole to fit the testers vacuum tube onto... Think I'll try that...
That may help, I've just inserted it into the hole but the angle and direction it sits at makes a difference and it gets a bit hot to hold it. If you don't get the reading fairly quickly then the probe gets so hot that the silicone hose to the tester melts, sometimes just a small hole but that makes the reading go well off...
Finally got round to doing my co2 setting yesterday...... Nice and easy except for the plastic tube melted as the adaptor I used was too short and got too hot Lengthened my adaptor and worked a treat Set both cylinders to 4.8, bike was a bit lumpy low down (2k-2.5k) when cold this morning but when warm ran a lot better One issue is the revs drop to 2k very quickly then take a second or so to drop to 1300 so I think it may be a tad lean I have read of others adding the 2.0 Base setting on the tester to what they want...wanting 4.8 so setting to 6.8 and they said that worked better for them so I may try that later, when I set mine it initially said 8.6 so it would have been too high using the other method too...
