angel
Enthusiast
- Messages
- 2,519
- Location
- Athens, Greece
My '75 R1123 needed to pass the emissions control test (once a year here) but it won't! CO is arond 2% at idle (OK) but goes up to 6,5-7,0% at 2500 rpm (second part of the test). The carb is a Zenith 28IF,cleaned and fitted with new gasket and needle valve. Needle valve height is the correct 8.4mm. Main jet is correct (I think so), it has only an "E" stamped, no dimension, but I have seen normal CO values with this jet before, furthermore I have two more same jets, which I tried without success.I also tried putting an "old style" SEV-Marchal fuel pump on, which,from my experience, gives lower fuel pressure than the sealed type that I had on. Still high CO. I tried lowering the float level a bit but this results in fuel starvation when I keep the throttle mid-open. Engine has covered 50.000 kms since major rebuild, air filter is new, ignition timing is spot-on. I think it is clearly due to over-rich mixture, but I cannot find why,especially since this carb is so simple. Does anyone of you have any ideas? Or maybe a similar experience with that carb?Thanks!