Hi,
I have a triumph 2500TC mark II 1976 with the twin SU 1.75 inch (HS6)
carbs on it. Have recently rebuilt them, as it just would not tune up,
could not get the carbs to run the same, would be horribly rich down low
and then really weak at revs., put in new throttle shafts, jets,
needles, bushes....has made one huge difference, and I keep looking for
the V8 that must have slipped in there somewhere, but haven;t managed to
find it hahaha.
Has anyone had experience with colortuning them for the mixture?? I
have mine tuned up so as after a run there are brown deposits on the
core of the plug, and a non sooty black deposit on the outside of the
plug, as all of the books say, but I still have not managed to get it to
go bunsen blue!!
I tune it up at 78 deg C (not quite the 82 that the thermostat is set
at, but hopefully the antifreeze I brought today should fix that) as it
runs at this on the open road, and it seems to want to run slightly rich
at idle (600 rpm I have it set at) and burns yellow. When I (or the
person conveniently sat in the cab) takes it up to 2000 rpm it goes blue
in the middle of the colortune but still stays yellow on the outsides.
This remains the same through to 2500 rpm, and fairly constant up to
2800 rpm.
Is this yellow and blue what they mean by bunsen blue??. I know what
bunsen blue is as I am studying chemistry,but.... As soon as I take it
to showing blue all over the view in the colortune then there are no
deposits on the plugs and they are stark white, so too weak and a bit
hot.
I am not too worried about it needing to be a little rich down low, as
people say that this is the same with the PI, and I guess that they are
really the same engine.
Have it running on leadfree 96 octane (with valvemaster to 'replace' the
tetra alkyl lead compounds, or whatever it is that they used to put in
the old stuff)
Any help very very much appreciated, Kenneth Williams, New Zealand.
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