Hack, the amount of excess / un-necessary fuel you have used over the last 18 years could have bought you a colourtune. Currently around the £40 mark. If you get rich readings at idle speed with the colourtune and cant dial it out by the time you reach 2,000RPM using the air / fuel screws, you likely have worn choke plunger seals assuming everything else is ok; Correct size pilot jets and not worn out, not overly restrictive air filter, standard settings for needle and needle jets etc.
Can i ask what reason for the rebore,... was it because you had very many small vertical grooves in the faces of the bores?
AL
Haha, yes, but checking my insurance mileage declaration I only did 135 miles last year and 120 the year before
, so not going have used much extra fuel!I've owned a colourtune for as long as I can remember but whenever I use it I don't find I can draw any real conclusion - I'll give it another go.
Everything is standard, carbs are good, all jets/needles were replaced and i have double checked they are correct again while the carbs are off this time. Air filter is new, and has been replaced over the years. One thing I did find this time was that the mesh gauze in the air box behind the inlet rubbers was well cruddy, possibly to the point where it would have impacted air flow. The gauze has two layers and the crud was not immediately apparent as it was between the layers. That's now spotless so I'll see if this changes anything.
I'd previously seen the posts regarding choke plunger seals so took mine out and they didn't appear hard or cracked - probably should have them done anyway.
Engine top end was off for other reasons and when measured, the barrels were just inside tolerance. It seemed mad not to put new rings in and when I saw the price for an IMD 1st o/size piston kit wasn't that much dearer than a set of rings I decided to go with that - whether that was a good decision will be apparent soon.
The bores weren't particularly scarred, I've seen worse,why do you ask?
Thanks Andy
If you find that twiddling the air or fuel screw does not have much effect on the mixture strength showing up on the colourtune, it could be that the idle circuit is being overwhelmed by the choke plunger seals leaking. 3/4 of a turn on mine which are fuel screws, takes it from one extreme to the other.
