Hi, I have read loads of articles on setting up my carbs on my 2.0 cu twin solex but I've got chance to do them on a co2 analyser this today and can't find the co2 figures for main carb and central idling on the machine, can anyone shed some light on what I should be setting them to please?
I think you're probably wanting to tune for carbon monoxide which will tell you how efficient you're burning the fuel. Assuming the carbs are balanced correctly, the only adjustment you can make is to the idle mixture screw. The main carb emissions are determined by the choke (which you need to ensure is open and the engine has warmed up) and the main jets which are fixed. I have a rather primitive CO meter. I just turn the idle screw until it gives a minimum reading. You may be able to get something more accurate if it's a professional machine. I always ask for an emissions print out at MOT time, and typically I get between 1-2% CO if that's any help. The MOT limit is 4.5%.
^this. Tweaking for 1-2% CO is fine. The idle mixture screw was primarily for emissions, rather than performance.
Cool. That's what I thought. The thing is I have a 4 into 2 exhaust. So I can tune each carb seperately to each can. Empi monza 4 type exhaust When I put the tester in exhaust each side was measuring something like 0.008 with central idling disconnected, 0.06 or close to with central idling connected. This can't be right. It wouldn't idle on just central idling either. It's my mates mot center so I can go back again but i got slightly thrown off by that, it runs ok so they can't be that far out. I haven't really touched the mixtures yet. :-[ a aargh. On a good note was out in bus all day and got quite comfortable using it, got a lot of attention too.
Also due to exhaust do I half the emmisions and set to that either side? Or 1-2% per side? Cheers guys
Monza 4 tip, isn't one tip per cylinder.... it's just a 4 outlet exhaust from the silencer... Do you have a picture of your exhaust
Ahhhhhhhhhhhhh I'd forgotten about that one!! Yeah, you'll need to half the emissions... 0.12% is very low... has the engine been rebuilt recently??
No, it hasn't been touched since being removed from t25. I have removed all air filter and have ram air filter pods on but I have used a stainless pipe that creates a trumpet effect about 5" long so it's not straight into carbs, il take a picture in 5 mins. Ps I never mentioned 0.12% it was leaner than that which I thought can't be right. If it was it was either the most efficient air cooled engine in history or runs on pure air. I see you are a type 4 man, what procedure for setting up mixtures do you use? I haven't got a vac gauge, I made. Homemade one with liquid in a tube and they seemed quite balanced. It does hesitate a little when low revs under load, kind of misses and jerks but put the pedal down a bit and it pulls off fine... My filter setup..... It's never a given but I'm sure the guy said it had 80k on when removed, runs well, one hyd tapped bit noisy rest ok, plenty of go in it. Cheers for replies mate
you measured 0.06, so I doubled it up to 0.12% TBH, if it's running ok, and not getting stinking hot, then I'd go with the "if it ain't broke" scenario... those type 4 solex carbs can be a real pain!! I generally go with the throw them in the bin and fit something better option!!
Ha yeah granted. School boy error with the maths... I touched the left carb screw a bit so I want to set it to same as other so mayaswell do both same time. New carb? It's not top of my list at mo plus it's an expensive upgrade. I do generally go by if it ain't broke.... Buuuut if they haven't had a tune in years it can't be a bad thing. Plus when first had it I was adjusting idle off stop screws on lever didn't understand central idling, different story now I can hold dipstick indefinitely but is does smell warm sometime, please forgive, first air cooled
So mr Weeding are you willing to enlighten me on your carb setup balancing procedure please? I read on a write up that you can run main mixtures a little lean on each carb and you can then run central idling a little rich to compensate. Ps I disconnected chokes, fast idle and rotated flaps because one of my choke flaps is broken and just flapped about. It was idling very low When i backed off stop screws so i needed to increase air central idle so that would then throw mixtures out yeah? That's the reason I wanted to check / set them. Guess somebody who didn't know how to set carbs had tweaked idling this way in past too...
