Decompression valve problems Ariel NG

[william.forsth]

Thanks John and Brenton, have to buy you guys a pint next time I am in the UK for all the help. The thing is that it is really easy to start, I usually just roll it, have a small slope just in front of my garage, but if not it normally engages in one or two kicks.

However, after a little while it dies again. It kind of feels it never really gets any power, it just feels weak....
I had the tank of and I cleaned out all the rust with citric acid, worked well. The carburettor I hav apart and cleaned. I guess I might have done something wrong here, if I cant get it to work soon, I just gonna have to go back and have another look at this item. Fuel, when I bought it, it was full of rust and crap, so I changed filter. So I really doubt that it is the fuel thing, but I cant rule it out. When it stops, it is not that hard to get started again. There is compression, so it is not the gasket for the cylinder. I guess it could be the spark, but would not such a problem be there from the beginning, and not just, or rather just quit delivering a spark ? When I bought it I had some problems with it and had the cable changed from the magdyno.

The main curiosity is the metallic sound, like a pebble in a bear can that you chake. I guess it has to be something under the rocker cap, either the valve or the arm that is hitting “something” I did believe at first it was the decompression valve, it showed on the exhaust valve that the had been hitting each other. Some wear and tear in the metal, fresh scrapes or dings so to say. I just thought that the old valve, that was kind of worn, and did not come apart was forcing the exhaust valve to open, or rather not close all the time, might still be this problem.

Just gonna take of the tank and the rocker caps again later today and have a look. One thought is that there might not be coming oil into the top, seems pretty dry up there.

[william.forsth]

did not really answer the question, it dies flat out, but it feels like it loses power. The first time I got this problem, I had driven like 5 kilometers before it just died, and after that, it has been much shorter, like yesterday, I came like 400 meters before it died on me

[william.forsth]

just one more thing, I just got stuped yesturday when I was gonna fitt my new petrol tap, the old on, clearly not original was a bit leaky, and the one i got from John B did not fit, it was like 13.0 mm and the old one is like 16.6 mm. It was directly screwed into the tank, so I was thinking, maybe it is some kind of middle part missing here, like an adapter or some kind of super special washer ???? I think I remember my friends BSA M20 having some sort of copper thing set into the tank, and then you screw the tap into that. if this is so? what is such a part caled?

[brenton.roy]

Hi William,
it is hard to diagnose problems without seeing and hearing the bike. I'm sorry about questions that might have obvious answers, but here goes.
1. How much petrol goes through the fuel line into a can in one minute? Does it come out at the same rate for the whole time?
2. When you replaced the High Tension lead, did you use a copper wire lead and a non supressor plug cap?
3. Does oil leak out of the banjo unions at the rocker cover, if you loosen the dome nuts? (with the bike running).
4. Are both rocker boxes "dry" on the inside?
5. What clearance gap have you set at the tappets?
6. When you take the oil cap off the oil tank, (motor running) can you see spurts of oil going into the tank?
7. Apart for the stone in the can, are there any squeaking or tearing (like rag) sounds before the motor stops?

It's just called an adaptor nut. http://www.hitchcocksmotorcycles.com/am ... s-fittings
If you go to the Uk, you'll need to buy young John two beers, I'm a little further away and I'm sure he wouldn't mind...
Poking fun at John aside, it's good to have younger riders working on their own bikes. Don't give up on it, it'll be something simple.
regards, Brenton

[william.forsth]

Brenton, Hi , yes I saw it after I posted that you are in Australia, sorry for that, but next time I pop by, I buy you a beer
Gonna go threw your list, and get back to you, have to look up some of the words as well, never learned the technical English so sometimes it is just a dead end The seller John Budgen , bless him, for understanding my descriptions of parts and stuff

[william.forsth]

Hi - just thought I update the current status. It is now clear that weather the decompression valve works or not, there is no oil circulation whatsoever! Been backtracking al the copper pipes and the oil canister, taken them apart, cleaned them etc, but there is nothing to remark upon. So I guess thats leaves the oil pump. when I took apart the return piping from the pump, the oil was all black and burned, so it has not been moving wot some time. (The bike has not been much in se for the last 25 years, about 30 - 35 km) when I opened the filter asembly underneath the engine, behind the bent metal guard plate, almost nothing came out. Bet there was some metal shavings there. I guess no one have cleaned it out in the last 50 years or so, and I have no idea what is the normal amount of metal bi products, but should I be worried ?

[Eero.Korhonen]

What about slugde trap, have you clean it?
Be, Eero

[william.forsth]

Hi Eero, the sludge trap, is that the little square plate fixed with four bolts underneath the engine? I took it out and it is currently in a bath to get it cleaned up. Or is it another sludge trap somewhere. I cant really say where the problem is, but I have no circulation in the system whatsoever. My gut feeling is that it has to be the pump, but it seems to be moving fine, I have not disassemble it yet however. When I loosen the two bolts that holds it in place, is it just to pull it straight out after that? Also, there is a metal wire fastened around it, it is not in the blow up pictures, so I am not sure what that is for?

PS Eero, was it you that tried to buy this Ariel in Jonsered, south of Gothenburg?

[Eero.Korhonen]

Hi William,
The sludge trap is in right side flywheel, it is a bolt looking thing.
http://www.draganfly.co.uk/shop/pi-4563 ... egoryId=75
In this picture it is 1077-33. If you take those two bolts off, the oil pump should
get loose. Metal wire is for security reasons.

No it was not me, maybe there was another from Finland.

Br, Eero

[admin]

When you drop off the pump, all your oil is going to leak out of your oil tank. The reason is that it is fed, by gravity, to one side of the oil pump.
I usually undo the feed pipe from the outside of the timing cover and block it with a wooden bung. That is messy but not as messy as having the oil ooze out of the timing cover while you are fixing it.

The pump is pretty easy to check. Two screws hold it on.
Undo any lock wire and undo the two bottom square nuts. CAREFUL as there is a a ball bearing and spring under each. Ball bearing in first
Clean inside and then drop the ball bearing back in and gently tap it onto the seat.
Not sure there are any specs on the spring length, but it might be worth some new ones.
You can test the pump by putting it in some oil and working the plungers yourself.

There is also a bearing and spring in the timing case on some model years. Have that out for the same clean.
I think there is info on this forum about doing that.

Put the pump back on with a new gasket to ensure close fit.
You can check the feed by undoing the rocker feed as that comes off the timing cover AFTER the oil pump .... even working the kickstart should be something out ...