Norton Trusty

[halfa]

Now the re assembly is mostly complete I decided to give her start up, she ran roughly and after turning off all I can get now is a few seconds of spluttering and banging. So all of the usual things were checked spark etc and the carb was given a good blast out with solvent cleaner fuel lines replaced. None of which helped so I took the head off and checked timing which was .150 thousandths too advanced. Hopefully this will help but it’s all very strange as she ran lovely beforehand and nothing has been done to engine in the meantime apart from external cleaning. But before reassembling the engine I noticed that there is a fair bit of sideways play in the piston. So I’m thinking re ringing may be worthwhile at this point. Can anyone recommend a supplier they have used for Norton piston rings. Thanks in advance.

[halfa]

Correction sorry, .150 retarded. Should be at .375 btdc my points opened at .225 btdc. Please correct me if I’m wrong I’m learning as I do it. Cheers.

[trusty220]

.375 is the decimal equivalent of 3/8″ which is the correct amount of advance. In my experience so long as the correct ignition timing is set it almost always falls down to a carburettor blockage. There are some very small holes and galleries in that carb and sometimes I find poking them out with a fine wire is the only way to clean them out thoroughly. Of course, if you’re using the fine wire method be very careful not to enlarge the holes otherwise it’ll never run correctly again.

[andyfrost]

Not being much of a man for the modern World , and all it’s gadgets , I somewhat reluctantly , after being told how good they are , purchased an Ultrasonic cleaner. I must say from my experience they are absolutely spot on for carb cleaning.
They do away withe hap-hazard method of “wire poking” , and the end results that it can bring.

Andy.

[trusty220]

I was just re-reading your posting and I remembered something that happened to me. At the time I thought it was a one-off, but it may have trapped you as well.

Have a look at the impulse mechanism on the magneto. It sits directly under the carburettor and when you flood it to start the engine, the excess petrol drips onto the impulse of the mag. This in itself doesn’t harm it but after a while the impulse gets dried out and sticks in the retarded position. This would explain why it is now retarded even though you haven’t touched any part of it.

I hope that helps.

[halfa]

Thanks for the tip on the ultrasonic cleaner, I’ll have a look around and invest in one. I’ve looked at the mag and the impulse does operate but when it trips it just goes with a little click but if I’m not mistaken shouldn’t it go with a nice snap ? Is there a spring involved in the mechanism that may have failed ? Thanks for this all this help.

[trusty220]

There should be a strong spring in the impulse mechanism which returns it to the fully advanced position once the weighted finger moves out of the way. You should hear a sharp click, quite loud, and the fact that you aren’t may indicate that it isn’t returning fully or quickly enough. Try dribbling a little engine oil onto the spring to start with and see if there is any improvement. The mechanism may have dried out and be binding on the shaft.

[halfa]

Spot on Geoff, mechanism stuck, given it a good oiling and its beginning to free up. I’ll let it soak in for a few days. Cheers.

[trusty220]

Glad to be of service! I knew all this rubbish inside my head would come in useful one day.

[halfa]

After a little break during the cold weather I started sourcing a few parts I needed to help finish her off mechanically and looks wise. The old carb float had a crack around the central stem so that would explain the over fuelling. A suitable donor carb was found and the float was perfect. As for the other running issues I decided to get the magneto professionally tested and overhauled, not cheap but worth every penny. She now starts on the first pull on the strap. Cosmetically all that was needed was some chrome caps for the oil and fuel tanks. A rotten Howard gem donated them and they look great with their aged look. I just need to post a cheque off to Geoff for some water slide transfers.

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[trusty220]

I’m glad to see that you’ve located some filler caps. I’ll have to remember that they are the same as Howard, that will make them easier to find if anyone wants any in the future. Luckily mine came with them so I didn’t have to go searching.

One thing that people ask me from time to time is,”Where can I get my Wico A magneto refurbished?”. Not being a standard motorcycle type magneto the usual restorers tend to turn their noses up at the humble Wico; could I ask you where you got yours refurbished?

[halfa]

Yes the gem tank caps are identical and the carburettor float was from an gem JAP engine too. The magneto refurbishment story you described was exactly what I came up against. Not because he didn’t like them but because he is so busy with motorbike ones. But with some persistence and the fact he only lives 5 mins from me, he agreed to help me out as a bit of a one off. I’m glad he did because he really knew his stuff. I will suggest to him there could be a market for him working on the wico A’s.

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