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Topics - gusmagicbus

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Singles / Running in troubles - engine fade
« on: 06 April, 2018, 20:45:22 »

I've just rebuilt a 1964 BSA SS80 (after 7 years and quite a bit of help from this forum!). Its had new big end, small end, piston, rings, re-bored barrel, valves, valve guides, bushes.....the works. After fiddling with carb settings and timing, it was running ok for the first test ride (around 12 miles). However, on a test run last weekend, after 20 miles the power delivery became jerky and then lost power, I could get some power back by shifting down a gear but soon lost power again. It still idled. It was a bit better after cooling down while I checked all the settings on the road side, but had the same symptoms soon after. I changed nothing and took for a ride this evening, and exactly the same thing happened after 4 miles this time. I have been keeping to about 1/4 throttle and speed between 30 and 40 mph to run things in. It feels like the loss of power could be the engine tightening somewhere but I'm not sure. My first move was going to be to take the head off and see if I can see anything unusual. But would appreciate any advice of what to look for first.

It has a few other things going on that I don't think are related, and aren't my priority until I sort this engine problem out (but just in case you think this is effecting it). The charging circuit isn't working at the moment, but the 12v battery has not dropped below around 12.4v  on the test runs as I have been keeping it on an optimate when its in the garage. Lots of oil leaks, but I don't think that's unusual. The first time I fired it up the exhaust glowed red hot, but since dropping the needle in the carburettor and changing the ignition timing to 1/16 BTDC (as per the BSA service sheets), rather than 5/32 BTDC (as per RR book) it;s run a lot better and the exhaust has not glowed. The spark plug seems a good shade of grey.


Singles / C15 brake pedal return spring location
« on: 28 January, 2018, 20:17:40 »
I'm rebuilding a C15 SS80 and just can't figure out how or where the brake pedal return spring fits. I have managed to fit it where I thought it might work but there's not enough spring pressure to return the pedal. Any advice or photos would be ace. Thanks.

Singles / The big day is nearly here..
« on: 27 December, 2017, 19:55:43 »
Hi Folks,

After seven years of hard labour, laughter, sweat and tears, it's nearly time to see if the BSA C15 SS80 runs again. It was my first rebuilt and not a single nut or bolt on the entire bike has been spared. New big end, cylinder rebore, new piston and rings etc. etc. I am looking for any advice on a sensible way to commission/run in?

Also i'm thinking of buying an oil filter protect all that hard work. What's the general opinion on aftermarket oil filters?

All advice gratefully recieved,


Singles / C15 Ignition Switch
« on: 11 November, 2017, 21:22:12 »

I am replacing the wiring loom on a 1964 C15 SS80. The wiring loom which was on the bike had (what I believe) is a 88SA switch and it was wired like this

The wiring loom I bought from ebay is wired like this and I think this requires the 63SA ignition switch. Does anyone know what the correct wiring and ingnition switch is for the 1964 SS80?

Singles / BSA C15 Carb
« on: 23 May, 2017, 23:46:45 »
Hi Folks,

I have an BSA SS80 1964 with a 376/281 Monobloc carb, I have stripped the carb to recondition it and whilst looking at carb diagrams I have noticed that mine has no air valve or associated operating gear. Although there does appear to be a hole in the carb cap for an air valve control cable. Do you know if the air valves were fitted to all the carbs in this series? I am also not sure how the the air valve is operated, I think there is meant to be a valve leaver on the handle bar, but looking at poor quality photos on the internet of SS80's i'm not sure I can see one of these.

Can anyone shed any light on my missing air valve?


Singles / Distributor shaft lube system
« on: 10 May, 2017, 23:06:20 »

I have stripped the distributor on my C15 1964 SS80. I see that there is an oil groove and long recessed area along the drive shaft (the bit half way between the drive dog at the bottom and where the cam presses on at the top). I am meant to pack this shaft recess with grease when I reassemble?


Singles / C15 Head Gasket Advice
« on: 05 February, 2017, 20:32:36 »

I'm rebuilding a C15 SS80 1964. I've measured the thickness of my cylinder head gasket (~.039 - .040") and bolted the head onto the barrell without the gasket and measure the thickness of the gap which is about ~.035 - 0.38 depending on which corner you stick the feeler guages in. Hence, compression on the gasket could be as low as .001" in one section.  I think the head has probably had one too many skims, and I am worried that the gasket will blow (or leak oil).

I guess a slightly thicker gasket would be good, does anyone know where I can get one off these or if there is another trick commonly used. Or even if 001" gasket compression is ok.


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