Difficult to start at my wits end

[Triton Thrasher]

You want the flow to be enough (with a bit to spare) for that time you use full throttle and maximum revs to overtake something,

Agreed. But here we're trying to resolve a starting issue.

Some people are.

 I was answering your post, which was irrelevant to any starting issue.

[RichardL]

... but for me the worrying thing with this case is how many distractions from the obvious culprit were allowed to frustrate the eventual solution...

RD,

I have to say, I don't think it is completely fair to talk about distractions here in a way that contends that the 'distractors' were out of place and should have kept quiet. I was one of them, along with others with more BSA smarts than myself, including yourself. After months and more than five pages of following the lack of progress, in spite of everything have been apparently checked, it seems natural and innocent that some straws would be grasped. This said, let me acknowledge that John was on the money back on page 2, as were you, when you agreed with the carb issue right after. Not sure why that was so easily abandoned. Well, maybe it was the multiple possibilities at play, with the mag taking the conventional (and here, undeserved) hit.

Richard L.

[CheeserBeezer]

... but for me the worrying thing with this case is how many distractions from the obvious culprit were allowed to frustrate the eventual solution...

RD,

I have to say, I don't think it is completely fair to talk about distractions here in a way that contends that the 'distractors' were out of place and should have kept quiet. I was one of them, along with others with more BSA smarts than myself, including yourself. After months and more than five pages of following the lack of progress, in spite of everything have been apparently checked, it seems natural and innocent that some straws would be grasped. This said, let me acknowledge that John was on the money back on page 2, as were you, when you agreed with the carb issue right after. Not sure why that was so easily abandoned. Well, maybe it was the multiple possibilities at play, with the mag taking the conventional (and here, undeserved) hit.

Richard L.

Agreed, RL. Logically, all the fingers were pointing at the fuel system, but a mag swap is easy and therefore eliminates the electrickery doubts in under an hour. Mags usually get the blame so, as it's so easy, just do it, if there is any doubt at all. Furthermore, whilst I have confidence in my work, as the mag is untried it cannot be discounted as the culprit. The mag was discounted after it worked fine on another bike so proved the problem was elsewhere. Furthermore BSA500 had said previously that he'd cleaned the carb in an ultrasonic bath so he was as confident as he could be that the carb was OK. BSA500 is the only person with his hands on the metal. The rest of us are functioning from various corners of cyberworld and we have to accept what we are being told. Agreed, it turned out to be a carb problem, as advised on page 2, but BSA500 thought he'd eliminated that. In the final analysis, swapping components is usually the easiest way of pinpointing problems so maybe swapping the carb is something which should have been tried sooner but, if you think you've already eliminated that, why would you? We're all doing our best to help each other.

[BSA500]

Yes in hindsight the carb swop  was pointed out early but at the time I was deeply involved with an actual mag repair and the carb sort of slipped in under the radar. Also I don't have lots of free time to play with the bike I do still work full time and have a family. The only spare carbs I had access to are not that great themselves the one on at the moment is actually for the iron head with a stripped thread on the Air screw. Also like alot of people I am not awash with cash so I have to chose my options carefully.
 But I don't regret the approach me and Andrew took we had to 100% rule out the mags and ot muddy the water with changing cars as well.
I do always come back to this forum for all the brilliant knowledge amiable here even if I miss it🤣

[sean]

Yes in hindsight the carb swop  was pointed out early but at the time I was deeply involved with an actual mag repair and the carb sort of slipped in under the radar. Also I don't have lots of free time to play with the bike I do still work full time and have a family. The only spare carbs I had access to are not that great themselves the one on at the moment is actually for the iron head with a stripped thread on the Air screw. Also like alot of people I am not awash with cash so I have to chose my options carefully.
 But I don't regret the approach me and Andrew took we had to 100% rule out the mags and ot muddy the water with changing cars as well.
I do always come back to this forum for all the brilliant knowledge amiable here even if I miss it🤣

just curious ...did you have the bike running and starting well when the carb was re sleeved ? usually any changes or modifications are the fist place to look if the bike was running well before .
glad you got it sorted and most of all told us what the problem was .

[BSA500]

Hiya yes after the resleeve it ran really well it was a few years back. Before that you could hear the slide ticking in the bore.
 When this time it broke down some muck was found in the pilot jet which was strange as it was too big to pass any of the filters but that's when the carb was ultrasound cleaned and all passage ways has compressed air blasted through.
 I think there must be some sort of fine sediment impacted in the pilot circuit. Their always seems to be a white residue in the carbs when  I strip then??

[KiwiGF]

Some tips here on clearing the idle circuit (if that is the issue), there will be other threads on this as well.

https://www.a7a10.net/forum/index.php?topic=6359.0

[TimK]

I spent a looooong time (2 yrs including changing/adjusting just about everything that can be changed/adjusted on a Monobloc) trying to sort out the carburation on my GF, finally spat the dummy and bought a new Monobloc and instantly had good starting/idling/acceleration etc. As was pointed out at the time, they do wear out and eventually get beyond resurrection.

[berger]

if my black&tan memory serves me right i think there is a possibility that the block can be inserted  a bit out of place and interfere with the holes, or am i talking sht again.

[BSA500]

Well you "shouldnt" be able to misalign the jet block because of the locating screw in the outside of the carb but we all have been on this planet long enough to know things can and will go wrong. No harm in checking that the slide seems to run run and the choke if you use one.

[berger]

mmmmm shouldn't i agree but here is a jet block not bottoming out with bottom jet nut on and locating peg in the slot.

[BSA500]

Strange indeed,is it the correct size for the carb body. Long shot stranger things have hapened

[BSA500]

That tickover screw isn't stopping the jet block moving down is it??

[berger]

no not the tickover screw,  but they can be held off bottoming out by crud or burrs or the screw locating peg not letting it all the way down . the groove in the jet block is not like a key way it tapers off and if the screw isn't taken out fully when fitting the jet block it can stop the jet block going all the way down.

[BSA500]

Right used the bike for work today a 13 mile ride through mainly country lanes and A roads. She ran really well, very rich, but very well. Seeing as the air screw thread is toast on my spare carb I will have to live with it better than too weak. I will have to get to the bottom of why my proper carb will not run. I had a close look at the pilot circuits and they look clear, shone a torch down the holes and passed some fine wires along the passages all passed.
 The body and jet block will have another session in the ultrasonic bath and another blast with the compressed air. all the other parts are on the spare carb so I know they are ok.
 A bit of a mystery. Another is a statement on the Burlen site they say if you use a flange gasket you don't use an o ring and vice a versa did I read that right. I have always used both