Darren Groves Posted October 19, 2016 Report Share Posted October 19, 2016 MK1 2L Vitesse with Twin CD150 Carbs. The carbs have been stripped, cleaned and had new O Rings & Diaphragms fitted. Pistons on both carbs lift and fall freely. On idle the car is nice and smooth but when you increase the revs the piston on the front carb lifts as you'd expect but the one on the rear doesn't lift at all. What's the most likely cause? Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 19, 2016 Report Share Posted October 19, 2016 Air filter gasket covering the atmosheric port Air leak in the top cover diaphragm mis located lugs and thebtwo holes in the bottom are not engine facing diapragm made from something too thick , They should be thin and very pliable pete Link to comment Share on other sites More sharing options...
Darren Groves Posted October 19, 2016 Author Report Share Posted October 19, 2016 Air filter gasket covering the atmosheric port Air leak in the top cover diaphragm mis located lugs and thebtwo holes in the bottom are not engine facing diapragm made from something too thick , They should be thin and very pliable pete No air filters fitted, so not that. Top cover seems a snug fit, so thinking that's probably OK, but will re-check tomorrow. Diaphragm lug located OK in carb body and are nice and thin, I have the old ones so can swap back to see it if makes a difference. "two holes in the bottom are not engine facing" - which 2 holes are you referring to Pete? Link to comment Share on other sites More sharing options...
trigolf Posted October 19, 2016 Report Share Posted October 19, 2016 I had a similar problem and found that at wider throttle settings - anything above idle - the throttle bar clamp nut was slightly loose and not turning the throttle butterfly. Link to comment Share on other sites More sharing options...
Darren Groves Posted October 19, 2016 Author Report Share Posted October 19, 2016 I had a similar problem and found that at wider throttle settings - anything above idle - the throttle bar clamp nut was slightly loose and not turning the throttle butterfly. Thanks for the suggestion. Butterfly opening OK..... Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 19, 2016 Report Share Posted October 19, 2016 With top cover off look down the sides of the dashpot , the bottom of the piston has two holes in it either side and behind the needle these should be towards the engine side not facing anywhere else its controlled by the diaphragm lugs and the location in the piston and the main body Pete Link to comment Share on other sites More sharing options...
Darren Groves Posted October 19, 2016 Author Report Share Posted October 19, 2016 With top cover off look down the sides of the dashpot , the bottom of the piston has two holes in it either side and behind the needle these should be towards the engine side not facing anywhere else its controlled by the diaphragm lugs and the location in the piston and the main body Pete Ahh....so the diaphragm could have been fitted 180 degrees out I guess?! Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 19, 2016 Report Share Posted October 19, 2016 Not if the lugs are in the right places but you get the idea just got the car back at last , its looking good , never did get any comunication from the insurance Co so mojo is restored to normal pete Link to comment Share on other sites More sharing options...
Darren Groves Posted October 19, 2016 Author Report Share Posted October 19, 2016 I don't recall any lugs on the inner part of the diaphragm, so it's likely I fitted with the orientation wrong on the piston. I hope I have anyway, as that would be a simple fix. Glad the car is now sorted. I'm still waiting on the recovery of the excess. Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 20, 2016 Report Share Posted October 20, 2016 Yes there should be lug on inner and outer diameters theres a few Tee shirts for this one Ha lets hope its that easy pete Link to comment Share on other sites More sharing options...
Darren Groves Posted October 20, 2016 Author Report Share Posted October 20, 2016 Sorted, missed the inner lug. So piston lifting as it should now. I'll order my T-Shirt..... Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 20, 2016 Report Share Posted October 20, 2016 Dont you just luv the simple fixes when they work what size tee shirt ???? Would that be then Ha ! pete 1 Link to comment Share on other sites More sharing options...
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