RUNNING AND MISFIRING

hi all
managed to get the bike in for an mot and it actually went and passed!!

1st time ive been able to ride it as even though it was insured you are only allowed to be on the way for an mot not out for a test ride

it started fine and reved ok and seemed ok until went to ride off,it would only rev up under load with the choke on slightly,which i at forst assumed was because it was cold,i managed to ride all the way there like this but it wouldnt idle at all with the choke slightly on so i had either no power or no idle
also when the throttle was closed it kept going bang through the exhaust
only thing i was able to do was take off the timing cover and try to shift the timing slightly , its got a boyer fitted already,this made no real difference
as its been standing a few years i decided tonight to take off the Amals ( 930 ) and give them a clean,noticed the sliders were slightly out of sync but otherwise all the jets and needle valve look ok
found the 2 o rings for the adjusters were not so good so i will replace them and check the float height tomorrow
not got the 2nd carb off yet

was wondering if anyone had any ideas , difficult i know with just a description and not seeing the bike

amal uk does 3 different kits from a basic gasket and needle valve and and one with all the jets
ive not ordered anything yet

cheers
matt

Matt, how are the plugs? Either clean with brake/carb cleaner and tooth brush or replace with new ones.

Then, start it up and put a strobe light on it to check you read almost 30 degrees at full boyer advance rpm.

Bang through the exhaust and choke on off issues? Sounds like - manifold leak, or Amal pilot jets gummed up, or low voltage to the Boyer or most likely all of the above. Do a search for Bushman's tips on Amal Concentric.

Mick

Matt
That's pretty much symptomatic of blocked idle jets, no idle, probably wont run under 2000 rpm off load, pops and bangs. Since the bike has been standing as you say the tiny (0.017) idle bushings block very easily with fuel deposits or tank dirt. I have spare drills here if you need one, just PM me yr address. Ideally they need to be blown out as well. Short-term take a strand of wire from something like a small starter cable (65/0.30) and try that. Even better if you have some of those plastic or paper covered twist wires that hold cables together on new electrical appliances that will do.

Keith1069 said:

Matt
That's pretty much symptomatic of blocked idle jets, no idle, probably wont run under 2000 rpm off load, pops and bangs. Since the bike has been standing as you say the tiny (0.017) idle bushings block very easily with fuel deposits or tank dirt. I have spare drills here if you need one, just PM me yr address. Ideally they need to be blown out as well. Short-term take a strand of wire from something like a small starter cable (65/0.30) and try that. Even better if you have some of those plastic or paper covered twist wires that hold cables together on new electrical appliances that will do.

Click to expand...

I agree with Keith, I had the same type of problem a while back when I bought a MK3 which had not been used for a while, I used some fine wire to clear the idle jets and it worked fine after that.

hi all
thanks for the advice and offer to borrow those drill bits

ive stripped both carbs and have given them a good clean out,although they were pretty clean really

ive also blown carb cleaner through the mixture hole,and on each carb theres 2 fine jets of cleaner coming out of the holes inside the body by the main needle valve so they look ok,they could have been partially blocked and now ok i guess

found the rubber o ring on both carb mixture screws had persished so ive refitted the carbs and awaitng these and a pair of air filter bellows as they were also beginning to split
i will try it next week when the parts arrive and keep u posted