Author Topic: Difficult to start at my wits end  (Read 5198 times)

Offline BSA500

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Difficult to start at my wits end
« on: 11.06. 2023 20:04 »
Hopefully I won't need to retime for a while. Re the spitting back I had Surrey cycles rebored and resleeved the slide so I am looking at fiddling with settings etc?
 I have just relapped the valves so I shall just see how we go.

Mod edit: merged topics Spitting back & Difficult to start at my wits end

1960 A7 (57 motor to SS spec)

Offline BSA500

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Re: Difficult to start at my wits end
« Reply #1 on: 12.06. 2023 12:29 »
Just a reply to my reply the slide has been sleeved so if I wanted to change the slide to a richer one(change from 3 1/2 to a 3) which I  cant now unless I send them the carb and get them to sleeve a slide to match?

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Offline RDfella

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Re: Difficult to start at my wits end
« Reply #2 on: 12.06. 2023 13:19 »
It is possible to tweak some slides (depending on model). Obviously making them leaner simply means increasing the cutaway (1/2 = 1/16th - how's that for maths?). Going the other way .... I have cheated on monoblocs by putting the slide in a lathe and turning 1/16th off the base. About as much as is possible, and you need to check first that shortening it this way won't affect the top of the slide closing off the bore. Bit of a bodge, but I'm no fan of buying bits just to see if they'll work. Get enough of that with my engine fabrications.
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Online Bsareg

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Re: Difficult to start at my wits end
« Reply #3 on: 12.06. 2023 16:21 »
I've  even built up the front edge of a TT slide with solder as a (very) temporary fix to check whether it was too lean. 🤔
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Re: Difficult to start at my wits end
« Reply #4 on: 12.06. 2023 19:40 »
Sorry Fellas I buggered up trying to split and move t 4am!

Quote from: BSA500 on 12 June 2023, 03:33:19

    Update time.
     Again Andrew at Priory magnetos came up trumps. Magneto sent and repaired and back on the bike in under a week. Excellent work as usual, HT side had failed also moving contact part of the points had worn oval. Andrew put all these things right plus some smaller bits and bobs.
    I am sure it would have fired first kick if of course I hadn't got the leads the wrong way round,50/50 chance 100% wrong everything  A bloody chicken would have a better success rate.
     Goes really well,still tends to spit about at the lower end but at least I know its not the mag now.
    Again thanks Andrew

'Spitting back' is nearly always due to worn slide. Surrey Cycles sell slides which are a couple of thou oversize. They need lapping in to the body with wet and dry in the body but I'd bet that's the route to curing that problem. Glad you're pleased with the magneto. A tip regarding plug leads..... When setting the timing on the bike make sure you are setting it on the firing cylinder (not the TDC piston on the exhaust stroke) and you will find that the heel of the points is nearest to the pickup which should be connected to the firing cylinder. I use a 'Left, Left, Left' memorising method. i.e. left cylinder on the firing stroke, heel of the points is facing left, and the left pickup is connected to the left cylinder.
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Offline BSA500

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Re: Difficult to start at my wits end
« Reply #5 on: 13.06. 2023 13:16 »
In relation to all this I may try taking the needle up one notch but in my heart of heart I believe I need a richer slide, if not to cure at least to improve to the point where I can set the rest of the carb settings. But as I have had the slide sleeved and carb bored that makes things a little tricky

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Offline BSA500

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Re: Difficult to start at my wits end
« Reply #6 on: 29.06. 2023 14:11 »
Update time. Had a bit of time to fiddle. Took the carb off and it looks like someone had sneaked in and dropped it to position 2 hence running weak(yeah alright it was me).
 Another discovery was the fuel tap. I have two newish bap taps. The main one kept weeping so drained the tank to replace the washers to stop that. The main one kept dribbling so I placed a large plastic jug under the tap as I spun it off. Good job I did as it dumped nearly 2 litres of fuel *eek*.
Why it held that much and didn't drop out the reserve I don't know .
I decided to poke about the the workings of the tap and found the stand pipe in the tap( thin plastic thing) had been twisted so restricting yhe flow how it ran I don't know.
 I cut out the twist but now it won't fit back in the tap so running without it,I did wonder why it was difficult to flood with that tap.
 

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Offline BSA500

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Re: Difficult to start at my wits end
« Reply #7 on: 04.07. 2023 13:26 »
Well it gets better(worse) riding to work Monday morning. Quite spitty still but it was quite chilly, improved as she warmed up. About six miles later she died as in fuel starvation so I switched to reserve but no go. So I tickled the carb plenty of fuel both sides still no start. Whip out the plug spanner, plugs sparking but dry. Bugger fuel blockage.
 Long story short recovered home strip down carb lots of crap in the pilot jet. clean out blow out all jets with compressed air rebuild still no start...
Got compression 150 both sides
Got fat blue sparks
Carb 30 pilot,106 needle jet 270 main 3 1/2 slide resleeved
 things of note plugs are showing signs of weak running. points are going to andrew as a clip had broken but it was still producing good sparks and recent mag rebuild. I will be checking and resetting the timing but that all looked ok. Anything i missed?? I am pretty sure I have covered most bases

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Offline Slymo

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Re: Difficult to start at my wits end
« Reply #8 on: 12.07. 2023 03:00 »
Sounds a bit like time to clean out the tank and to check the strainers on the fuel taps. Perhaps replace the fuel lines as well. If there is junk turning up in the jets there is only one direction it can be coming from. I must admit my 376 is slow to tickle but it does flood in the end.
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Offline BSA500

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Re: Difficult to start at my wits end
« Reply #9 on: 12.07. 2023 08:53 »
Tank clean,fuel lines cleaned,carb ultrasonic clean filters checked and cleaned. Points repaired on their way back with some new plugs. Fingers crossed

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Re: Difficult to start at my wits end
« Reply #10 on: 12.07. 2023 09:01 »
Just a reply to my reply the slide has been sleeved so if I wanted to change the slide to a richer one(change from 3 1/2 to a 3) which I  cant now unless I send them the carb and get them to sleeve a slide to match?
G'day 500.
Not necessary, You can take 1/32" off the bottom of the slide. Just have to lift the needle the same amount.
Cheers
'51 A7 plunger, '57 A7SS racer now a A10CR, '78 XT500, '83 CB1100F, 88 HD FXST, 2000 CBR929RR ex Honda Australia Superbike .
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Offline BSA500

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Re: Difficult to start at my wits end
« Reply #11 on: 10.08. 2023 16:29 »
Update after exhausting all other avenues sent the mag back to Andrew and the insulation had broken down . Armature replaced all set up and now back on the bike. Runs a whole heap better but yep still spitty and embarrassing at the lights by spitting back and stopping. I might raise the needle another notch but not expecting much improvement

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Re: Difficult to start at my wits end
« Reply #12 on: 10.08. 2023 19:42 »
Have manifold air leaks already been discussed?

Offline BSA500

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Re: Difficult to start at my wits end
« Reply #13 on: 10.08. 2023 20:02 »
I have checked that out already and checked the carb flange for flatness etc

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Re: Difficult to start at my wits end
« Reply #14 on: 10.08. 2023 23:08 »
You sprayed WD40 at the joints while it was idling?