Ariel Arrow starting

[White.John.A]

Hi All,
When I started this project, I quickly came up against the bike starting on one cylinder only. It could be either side. I have since the early days rebuilt the engine and tried many things to make it run properly. I have used electronic ignition without success. I have now refitted the points. The bike now starts quite easily, but only on one cylinder. Yesterday it started after about 10 kicks. The near side try’s to run but cuts out. Today it is the near side cylinder that runs but the offside doesn’t. I have taken a pressure reading and each cylinder has dropped to 85 psi. This suggests an internal problem. But the bike starts quite easily on one cylinder at this pressure. Has anyone had a similar problem.
John

[simon.holyfield]

Got to be a sealing problem?

[Ivor Collins]

Hi John

Could be seals, strange how it moves sides though.
Have you tried starting, then pulling the HT lead off the non running side and holding it close to the plug just to prove the spark? Providing a large gap for the spark to jump increases the voltage and can provide benefits too.

Have you thought about fresh fuel and ensuring not too much oil in the mix just to get it away? I also wonder if a really bad carb setting could leave an engine barely able to run and chance which cylinder it manages. Do you have a spare to try, where are you?

Regards
Ivor

[White.John.A]

Hi Ivor,
I have checked the spark in the way you suggest. All was fine. A friend of mine suggested getting fresh petrol, which I have now done. I have not tried lessening the oil. By how much reduction would you recommend. I have purchased a tool to check the fuel /air ratio. It has not arrived yet. If it shows the carburettor to be working correctly, I will check the seals.
Today the bike started different to previous starts. It would not start chocked. It started on the near side cylinder only. While running really rough, I closed the choke and the off side cylinder cut in. So I’m bigging to think the carburettor is the problem. I do not have a spare carburettor and will have to Waite until the new tool arrives. Quite a large quantity of fuel comes out of the non running exhaust. More than I would expect.

JOHN

[Ivor Collins]

Hi John

Fresh fuel and 32:1 should be fine, just best to avoid the idea of extra oil for running in until it's starting ok and back on the road.

I know you have tried both with and without electronic ignition but that does not exclude the coincidence of a problem with both systems or on the unchanged HT side, there is no shortage of reported problems with electronic ignition on this site though you do seem to have established a strong spark on the failing cylinder when the engine is running.

Fitting in line spark plug tester/indicators would monitor the spark of both cylinders when running. I have not tried the fuel /air ratio meters so would be interested to hear feedback on their usefulness or otherwise, not sure how it will work to analyse the exhaust of a non running cylinder, the idea of fitting lambda sensors in the exhaust pipes of multi carb machines has always appealed to me as a tuning aid but not yet tried it.

Regards
Ivor

[iansoady]

I suspect a fuel / air analyser would give weird results with any two stroke, especially one not running properly in the first place.

My Arrow is running very nicely on 30:1 synthetic - smokes with the rich mixture on startup but once the choke is off very clean.

[White.John.A]

I have been looking at problems members have experienced in the past. All, seem to have concluded the problems similar to mine have been a problem with the seals. The easier job is to check the carburettor, so I will do this first and then I am beginning to think I will have to check the seals AGAIN. Very disappointing. Thank you for your help. I will keep all you have said in mind as I continue to work on the bike.
JOHN.

[White.John.A]

Hello all, I am looking for some help again. I am in the process of checking the carburettor. In removing the pilot jet I have found that it is blocked at the chamfered end. it is clear between the far end which has a screw thread and screw driver slot and the two holes half way along the jet. Can any one tell me if it should be clear right through.
JOHN

[bh.sprint]

Hi John,

I've just checked two pilot jets and there is a hole right through. I've not push a thin piece of wire thro but I can see light at the taper end from the threaded end.

Brian H.

[White.John.A]

Thank’s Brian. I know you shouldn’t do it, but I tried to push a wire through, but it was solid. So I began to think it was as designed, although I wasn’ t convinced
John