1955 Huntmaster Questions

Singles, twins and fours.
jon.hursty
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1955 Huntmaster Questions

Postby jon.hursty » Mon Nov 19, 2012 4:25 pm

Hi All,
I have been rebuilding my 1955 FH for the last 6 months (mechanical & electrical) & have found this forum a great help.
I now have a few questions of my own.
1) Oil Tank Cap, I have had one made but does anyone know if it should have a vent hole in it as I cannot see any vent on the oil tank itself.

2)I have a Burgess Air Filter which has a level mark in the bottom half, I take it that I soak it in oil up to this mark, what type?

3) I have had my Magneto rebuilt(K2F) but have trouble with the ATD unit which is goofed/us & I cannot find anyone selling new units anymore.
Is it possible to convert my mag back to manual advance & would this be a good idea on the FH or other suggestions welcome.

Thanks in advance.

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PeterW
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Postby PeterW » Mon Nov 19, 2012 8:40 pm

Its a long long time since I had my '55 FH but I'm fairly sure the oil cap had a vent. And if all else fails with the mag just lock it somewhere near full advance. Kick starting will be an adventure but once on the move I never retarded it.

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Postby pete.collings » Tue Nov 20, 2012 12:13 am

I think other threads have suggested too small a vent hole can allow oil to seep out, as it can froth a bit on being pumped into the restricted space at the top of the oil tank, perhaps open up the hole a bit on the inside of the cap.

I used a replica (fibreglass) burgess type oil filter on my huntmaster, but never bothered too much with what went inside, if you use oil perhaps use a tacky type (I think there is an oil made for use with scrambles type foam filters). The positioning of the inlet at the rear of the filter will greatly reduce intake of muck, especially in a damp climate. You may need to occasionally wash out any muck accummulated inside the filter.

I believe Roy Price, who advertises in OBM and other publications, reconditions ATD units, although they are not that cheap. I have repaired them in the past by riviting on new fibre gearwheels (sold on Ebay), and replacing the self extracting centre nut, but if the extraction thread in the body of the ATD unit is damaged, it can be nearly impossible to remove it from the magneto shaft.
I have run a huntmaster in both manual and auto advance format, I prefered the auto setup for better control over low speed running and tractability (less fiddling with handlebar controls at low speed/when manouvering). If moving to manual advance, you may need a new end and cam ring for your magneto (as well as a cable and handlebar control), or you will be stuck with full advance all the time, this can be lived with (as PeterW's reply above) but is not as good as having retard at low revs.
Also be aware there are different advance options for ATD units, you would need one with around 17 degrees.

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Postby john.whiting » Wed Nov 21, 2012 10:41 am

Im not positive,but I think that the manual advance mag has a different end drilling to the auto advance mag,however a mag from a Matchless CSR twin wll be of the compy type,and were once very common.[all the motors blew up].An advance unit shouldnt be hard to find ,there are usually one or two on ebay every month.Look for BSA A7 or A10,of course.I have never had any trouble with the extraction thread,but I think you could tap a thread thru the centre and use an extractor screw.Regards John.

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Postby pete.collings » Wed Nov 21, 2012 2:27 pm

The manual mag normally has 3 screw holes, whereas an auto mag has 2 diagonally opposite. With a manual end as a guide, it is easy to drill the additional hole (s) needed, and tap them to 2BA. I have done this in the past, but then I do have a set of BA taps and dies, items that are not so common these days.
Be aware that some manual magnetos (mostly Triumph I think) had larger screw holes and different ends to match.
The problem with a damaged self extracting thread in the ATD body is removing the self extracting screw itself, normally it should just screw out by hand (Left Hand thread), sometimes a level of (controlled!) force is needed to remove it if it is damaged. I have never tried tapping a ATD centre to a larger size, but I guess if you can drill out the remaining LH thread, there is no reason why this should not be possible, although I don't know what thread size/type you should use.

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Eero.Korhonen
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Re: 1955 Huntmaster Questions

Postby Eero.Korhonen » Thu Nov 22, 2012 6:19 am

Hi,
Here is one place to order BA taps and dies:
http://stores.ebay.co.uk/HelicallKING
-Eero
Ariel VH 1954, IZH 350 1962, H-D Sportster Hugger 1992, AOMCC Member 133

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Postby john.whiting » Thu Nov 22, 2012 10:37 am

What I said was not correct,I have tipped out a large box of old mags and drive gears,and clarified the matter. The A7/10 type auto advance mag can be converted to manual with the corresponding end,most commonly fitted to Matchless G9s of the early fifties.This end has a characteristic domed cover with a centre cut-out button and is held on by two long studs.The competition type mag has a larger screw spacing,four screws,and usually a knurled screw-on cover,often with a breather or pipe fitting.This mag and a solid drive gear would have been fitted to the RGS,and possibly to the Road Rockets.If you run your motor on fixed advance,it would want to idle at 2000 revs,and probably spit back as you took off,as well as knocking. I dont think BSA ever used BTH mags,on the twins but Triumph did,and Ariel.The BTH mag was an extra cost option,but police bikes allways had them out here.Regards John.

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Postby jon.hursty » Sat Nov 24, 2012 11:31 am

Hi All,
Many thanks for all the replies and just to update you I have managed to buy a second hand ATD Unit.
I am hoping with a clean up & new springs etc it will be OK.
All the best Jon.


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