Petes.one you were correct regarding the main jet height. it was too high and not allowing fuel past. i have adjusted it and it now fires on the turn of a key although revs are high (with idle adjuster set to no contact with throttle arm). if i increase revs the revs return back down very slowly.
Thats the main issue at the moment, high revs and slowly returning. I have adjusted the distributor location which doesnt seem to have much effect.
Any other pointers? Can anyone suggest a suitable needle to try?
Hi mate what needle you using at mo,as with 286 gonna need to be quite a bit richer than standard?
Standard airbox and filter,or k and n or similar?
Sound very lean if revs slow to return,have you tried adjusting mixture while its running,?
my 1380 needed to have screw wound right in just to get it to run ok,hence needle was too big(lean).
I assume the dashpot pistons returning ok and throttle cable not sticking?
You can richen your current needle by reprofiling it youself,file a flat on one side,not too much,it doesnt matter that its not round as its the amount of fuel delivered thats important.The bottom of the needle,the part nearest piston will control idle and part throttle, as the needle is raised the rest is gradually in use,if you look down the back of carb and lift the dashpot piston you can get a better idea of this.The more you remove the richer the mixture.Dont go mad with it as were only talking very small amounts.
This is a trial and error method but it will pay off as you get a better understanding of the effect of carb settings.
There isnt always an ideal needle,but you could start off with BDL,the jet should be between 1 or 2mm down from the bridge when your near a good setting,also check plugs for signs of lean or rich mixture after use, turn off engine straight away to get a more accurate reading.obviously dont run it hard if it feels lean as can cause damage to valves and pistons.
Your Know when you get close as it will feel better to drive, a way of getting a feel for the mixture is to try extremes and drive ie. lean it out and will be quite flat and will start misfiring richen up too much and will cough and splutter.
I suggest you get the david vizard book on engine tuning as its very interesting and helps you understand why things happen on an a series.A word of warning,when the engines in neutral and under no load it can be too lean but feel ok,you need to drive maybe up a slight incline in a high gear so the motors working to get a idea whats happening.
Remember the 286 wont come on cam until around 2,500 to 2,750 rpm so make sure you on cam when testing as below this is very hard to get a good setting,normally end up being too rich,but thats the price of more mid and top end.
Hope this helps mate and dont give up, i spent many nights testing to get it right.
Its worth it in the end
Forgot to say and ask what dizzy you using and does it have vaccum advance connected,?you may need to play around with the dizzy to get the best out of it,anti clockwise to retard clockwise advance,once the mixture is fairly stable try advancing until you notice revs pick up then back off a fraction and try,keep an ear out for detonation under high load ie up hill,retarding the timing will give you more top end but a very poor bottom end,advance will crispen it up and make it more driveable.
Its all good fun,just try one thing at a time.
with regards to oil pressure aim for around 60 psi when hot,an adjustable one is definitely worth it if its too high or low.
Dave
Edited by Dave33, 27 May 2010 - 10:41 PM.
