Can ignition timing jump out of sync VH

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john.whiting
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Re: Can ignition timing jump out of sync VH

Postby john.whiting » Fri Jun 22, 2018 12:47 am

remember that you must set the timing with the engine rotating in the normal direction,to take up slack.Rotate the engine backward enough to then turn it forward enough to take up all the backlash ,or the timing will be way off.

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Re: Can ignition timing jump out of sync VH

Postby nevhunter » Fri Jun 22, 2018 1:24 am

Run the engine with the cover off after setting the timing. You will only lose a small amount of oil. Move the advance-retard through full travel IF you know what to look/listen for .you do a quick but effective check that the timing is close to what works. It should hunt on full advance, and slow up considerably at full retard with stronger sound. The best way to make an adjustment is with the sprocket on the cam. It's a bigger diameter taper. The magneto is hard to stop the shaft turning when you release /tighten the nut. Holding it by the point s assembly is not advised. Never try to prise a sprocket off. Use a proper Ariel puller. The Lucas magneto-dynamo shaft is easily distorted/bent as it's way out from the support bearing and part of it is BRASS with only 2 screws through the armature to align it. Nev

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Re: Can ignition timing jump out of sync VH

Postby ChrisNewton » Fri Jun 22, 2018 9:25 am

alan.moore wrote:Chris,
Re setting the points gap the fixed point (i.e the one that is not the one on the spring steel arm) has two small nuts. The lower one is a locknut, the top one, when turned, moves the fixed point up or down.
Rotate the backplate until the points gap is at its widest point. Measure with a 12 thou feeler. If it needs adjusting slacken the lower locknut and screw the fixed point in or out to set the gap. Then holding that in place tighten the locknut.

Cheers
Alan



Alan
many thanks - whilst this looked the way to go to go i just needed someone to confirm this - living by the "if it aint broke dont fix it " rule i have never had to do this - that said the bike has only done 200 miles since a rebuild ...not by me though

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ChrisNewton
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Re: Can ignition timing jump out of sync VH

Postby ChrisNewton » Fri Jun 22, 2018 9:28 am

nevhunter wrote:Run the engine with the cover off after setting the timing. You will only lose a small amount of oil. Move the advance-retard through full travel IF you know what to look/listen for .you do a quick but effective check that the timing is close to what works. It should hunt on full advance, and slow up considerably at full retard with stronger sound. The best way to make an adjustment is with the sprocket on the cam. It's a bigger diameter taper. The magneto is hard to stop the shaft turning when you release /tighten the nut. Holding it by the point s assembly is not advised. Never try to prise a sprocket off. Use a proper Ariel puller. The Lucas magneto-dynamo shaft is easily distorted/bent as it's way out from the support bearing and part of it is BRASS with only 2 screws through the armature to align it. Nev



thanks - i have the correct puller for the sprocket ...once i have it running i may try this technique :D

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Re: Can ignition timing jump out of sync VH

Postby ChrisNewton » Fri Jun 22, 2018 9:29 am

john.whiting wrote:remember that you must set the timing with the engine rotating in the normal direction,to take up slack.Rotate the engine backward enough to then turn it forward enough to take up all the backlash ,or the timing will be way off.



thanks and noted

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ChrisNewton
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Re: Can ignition timing jump out of sync VH

Postby ChrisNewton » Fri Jun 22, 2018 11:54 am

Update - have it running - sounds terrible so will go down the trial and error solution of advance and retard in the middle and run it so i can adjust to hear what is best
i did follow the tech solution several times without it starting - i opted for the set it st 20.00 hours on a 24 hour clock or 20 to and got the baby running again
so will now follow the rule of thumb till it sounds right and revs correctly - it was running so sweet the other day before i parked up

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Re: Can ignition timing jump out of sync VH

Postby ChrisNewton » Fri Jun 22, 2018 6:06 pm

it is cured ...thanks to all for help.

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chris.shearwood
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Re: Can ignition timing jump out of sync VH

Postby chris.shearwood » Sat Jun 23, 2018 12:36 pm

Please tell us what had caused the timing to be off.
1946 4G, 1950 NG and 1951 VH

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ChrisNewton
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Re: Can ignition timing jump out of sync VH

Postby ChrisNewton » Sat Jun 23, 2018 1:01 pm

Chris Shearwood ....short answer is i don't know .....i rode the bike in to the garage about a week ago it was running fine.

i went to ride her again on Thursday evening , several kicks and it coughed an spluttered - so i checked the carb and fuel then looked for a spark

all present

So i could only imagine it was ignition timing - strange thing is i could only get it to run on the 8 o'clock set up - i followed the instruction to the letter on how to do the ignition timing by john.nash ( i must of done it 5 times ) and as i read and re- read the thread i noticed a comment from john.mitchell about the 20 too solution
this at least had the engine running although it sounded and run terrible ...so advancing it a bit improved it and i kept moving it until it run well

I have a mark on the mag now so if it slips again i can do it very quickly - which is nearer to the 10 to (22.00 hours) so quite why that is i don't know

perhaps someone on here can shed some light ?

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Leejm
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Re: Can ignition timing jump out of sync VH

Postby Leejm » Sun Jun 24, 2018 8:50 am

I lap the sprockets onto the mag and camshaft with grinding paste to make sure a good tight fit so they don't slip in use.
1948 NH, BSA D10 SPORTS. 1953 VHA, 1951 KH rigid project.


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