Hi spent most of the time while I've been gone stripping the carbs down ,cleaning all parts etc but before I did that I check and noticed slider on number 2 was very slow in coming back down to rest . All sliders lifted while applying light air pressure but 2& 3 had a slight air leak at the diaphragm cap. Pilot jets were blocked on 3 &4 all , emulsion tubes main jet and air jet appeared to be ok. Vacuum tested all chokes and appear to be good working order. All float needles appears to be shutting of fuel. My main concern was float height measurement not the easiest to do . So I tackled it in a different way. See what you think. I emptied all float bowls and measured the contents . 1 & 4 the same, 2&3 the same . 1&4 slightly more than 2&3, so I put this down to extra fuel in the feed pipe , so I filled the bowls again with 4 equal measurements that I obtained from 2&3 . Then removed the fuel pipes , then emptied the the bowls again , all four came out equal. So I pretty sure all float heights are the same , there's no reason why they would of been messed with considering the history of the bike . So today the carbs will be going back on . To be continued
well backfiring on number 2 , at idle , didn't like mixture screw at 2 turns out , then disaster struck, the tit broke of the diaphragm top vacuum pipe . What would cause the backfire at idle ? it only happens at idle on number 2 .
Weak mixture ? Possible cause cracked carb to head inlet rubber pull the choke on a small amount, does it improve / go away ? or an air leak at the top cover for the diaphragm because the top was cracked to start with, move its position to another carb and see if the fault moves too ! What are all the other carb idle screws set at ? Try them all at 2 1/2 turns out and readjust individually to get a balance, not necessarily all set the same Recheck all the HT connections are good and also the LT connections to the coils. Have you checked the valve clearances ?
You can check carb inlet rubbers by spraying them with wd40 with the engine running. It shouldn't make any difference but if it does, you have a leak and the wd40 stopped it temporarily.
Cheers , I'm waiting delivery of a carb top and then have another attempt . It needs very little choke but does needs it .
How do you mean it needs a little bit of choke ? to clear the misfire ? or to keep it running ? Do the exhausts smell of petrol ? if you have all the carbs set at 2 turns out that is likely to be on the lean end of the range anyway at idle I would open them all out a further 1/4 turn