Carb issues advice needed please

[kartman]

I have a problem on my 650 engine with the carb, i only bought the car at the weekend and it is a real b#tch to start, sometimes running the battery flat without even a cough, it is no better when the engine is hot. The only way to stand ANY chance is no choke even when cold. If you are lucky enough to get it started if you move the choke it kills it straight away. I have had a quick look at the carb and the mixture screw has been turned right in! I have unscrewed it 1 1/2 turns  but it still is  the same, i think the seller knew there was a problem as he said his mechanic had `adjusted the mixture as it was running a bit rich`. I have bought a w/shop manual but am waiting for it to arrive, any idea  where to start looking on the carb for the fault, once running and warmed up it seems to run smoothly...........Martin

[nrg19uk]

Hi Martin
 The fuel runs back out of the mechanical fuel pump back in the tank which makes it take forever to start. I've fitted a electric fuel pump and it now starts first pull. If you click the subscribers section at the top of the page the manuals are available for a small fee.

[kartman]

I dont think that is the problem i can stop the engine from hot then try it 3 mins later and it won`t start, and once started from cold even a slight pull on the choke kills it straight away..........Martin

[Darrell]

Might not be the problem but I agree with nrg19uk, the electric pump is the way to go.

I found a little carb bolted to the top of a hot engine..often when hot it would need to be cranked a alot to start.

There is a manual on this website available to subscribers you need not have bought one  .

Pretty sure the manual will explain the carb set-up 

[dajwid]

I had the same problems.

Changed pump 'electric',  Plugs , points, timing, changed over the carb (and gaskets) for recon unit, still same problem. drained fuel and filled with fresh. Still same problem, changed over the insulater on carb, no change Aghhhhhh! by this time it would,'t even start.
Put in original plugs and she runs like a dream. fitted new plugs and all seems fine now.

good luck (and don't let the bloody thing beat you) 

[GTMaster]

If the carb needs to be pulled apart anyway, then check the float level and the condition of the float and float needle (it will be in the service manual). If that setting is ok then you just need to check the jets (check if the correct ones are fitted , should be listed in the manual) and then the idle can be properly set. The electric fuel pump probably does help a lot, but i have no problems at all with the original setup in my car (starts in the cold first time everytime.) True, however that if the engine is hot and left to cool for about 15mins it does need a bit more cranking to start afterwards.

[kartman]

Thanks for tha advice, i have removed the top elbow from the carb and there is definatly plenty of fuel there, if i operate the throttle i even get a little spit or splash back out the top of the carb, there looks to be quite a lot going in.......maybe too much. The top of the carb is all black and caked in what looks like hard oil deposit which would be consistant with it blowwing lots of oil through the breather. This i am hoping was caused by the missing disk at the bottom of the oil filler cap (new cap now on), i can`t see whether this has cured the smokey breather problem becuase it won`t start 

I Will get to the bottom of it, i am borrowing a compression tester today as i hope that the oil smoke from the old oil filler cap is not an indication of knacked rings.........Martin