Bike not running right after Xmas lay-up...

[Ethelred]

a very small movement of the pilot needle will make a drastic change to the engine.

That's very true. When I hooked mine up to an exhaust gas analyser it I was amazed to see how much a quarter turn would alter the mixture.

[Butch (cb)]

Well as I had to pop over to the docs for more pills this morning, and all was clear and dry outside I figured I'd take the A10 over. As noted elsewhere I've probably not started it since maybe October time. There was a fine coating of dust in the light oil that covers it when not in use, and the tyres needed the best part of 10 psi adding each end. Clutch cleared fine and then after a couple of sounds of life from the very first kick it fired and ran at about the fourth attempt. And soon settled to a nice tick over and then rode out just fine. Nice bike actually.

But what of stale fuel and associated debris and sediment build up? I'd not even bothered to let the carb drain before storing. I do use high octane in this one whenever it is available, and I do always dose up with Castrol Valvemaster and octane booster. Does that make a difference? Or did I just get lucky?

[bsa-bill]

I do always dose up with Castrol Valvemaster and octane booster. Does that make a difference? Or did I just get lucky?

I use that stuff too and the two bikes always start first or second kick, the lawnmower  OTOH gets pure petrol and took a lot of pulls to fire then stopped, more pulls then it started, ran spittingly for a while before setling down
 

[Ethelred]

Similar experience to yours Cyclobutch, though I take even less care than you, put it away, start it up a few times over the winter, that's it. Started about 4th kick after draining a pint out the sump. However the proportion of ethanol in fuel nowadays varies considerably by country. In the States it's quite high and I presume in Australia and New Zealand the same is true. In the UK I think it's lower and non-existent in the go-faster stuff, so experiences vary. We might do well to note their experiences because I think our refineries are going the same way.

[muskrat]

I might have to move up there! The only time my bikes get laid up is if they blow up!!!
Ethanol goes off quicker than the missus. Down here it's 10% in 91 octane only, 95 & 98 are fine. Some stations even have 91 that's ethanol free.
Cheers

[RichardL]

Mick,

What a frustrating story. You probably feel like you need a forklift to haul your right leg around.

Carbs are not my strong suit either, so I leave any advice in that area to others. It does sound to me like you could have mag trouble. One thing you or your mechanic could do cheap is to install a Brightspark EasyCap. If it fixes the problem, Bob's your uncle (not you Topdad),  if not, it's a cheap improvement that has done you no harm.

Richard L.

No, I am not related to Ken or Groily (boys, send the check to......)

[mick43]

So the recommended dealer/mechanic has the bike and has stripped it down..

Initial finding is that it has a 500cc mono bloc carb 

I have agreed for him to purchase and install the right carb for the bike - as I want it right, and for him to fit and tune. He also said the old carb had wrong jets as well (but again it run sweet/ok for me at least - hopefully I will be pleasantly surprised by the new performance!).

I'll keep posting updates - carb due to be fitted next week.

[morris]

Do have a look at the magneto though. Had a similar experience on the swingarm lately.
Blamed it on the carb, although it was only one year old and of the correct type, bought directly from Amal.
Fiddled with pilot jets and air slides, but kept on having similar experiences as yours (wet plugs, lumpy running, stalling when opening the throttle).
I then dismantled the magneto and found the the slipring had a hard carbon deposit all around, so I gave it a light skim on the lathe. After that it ran flawless for about 2-300 miles before the symptoms returned. I think it must be due to bad quality brushes.
Anyway, I converted to electronic ignition now, and very happy with it.
The magneto however will be refurbished, and continue doing service on the plunger

[mick43]

thanks Gents for all advice and help...

I can report though that bike is now running great.... 

Local BSA experienced garage replaced Amal carb with correct type and all ok, starts first/second kick and rode home today (circa 17 miles) without incident.

So I don't know what went wrong with old carb, they did say it's in good condition, but wrongly jetted etc for the Super Rocket...

[muskrat]

Great to hear Mick.
I can't understand how the bike ran well with that carb before winter and now wont.
With the right carb and tune I'm sure you'll be very pleased with the performance increase.
Cheers

[morris]

Great news! Always nice when it turns out that the cash you've spent was well worth it

[Butch (cb)]

Does seem weird that the carb it used to run OK on now turns out to be wrongly and wrongly jetted all the time. The ghost in the machine?