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[Simplo]

Nothing do to!
Today I tried again and the problem is always the same. Engine runs only with choke.
I didn't changed a single thing from yesterday when it was running well.
The only "randomly moving" part I can thing is the float!!!
Any way to check it?
Thank you all!

[Mark M]

It seems that the problem remains despite all the things you have done to the carburettor. Does anyone else think that this might just be an ignition problem? I'm not familiar with these Indian models but it seems to me that the almost random change between running well and not running is more symptomatic of an electrical problem?

REgards, Mark

[Adrian]

I did wonder after so much has been done with the carburettor. Creaky 45 has already suggested that the actual problem could be a failing points capacitor, which no-one else seemed to pick up on, though I have also had a failing rectifier produce similar symptoms on a Honda 125 years ago.



A new carb for the 350 can be had cheaply enough, if the symptoms persist it is definitely electrical.



A.

[Creaky45]

I think you are going to have to borrow another complete carby, slide and all and prove for certain that it is a fuel problem. It's got everyone stumped but that's what Enfields do. I would still try a new capacitor if you have one. It can go outside the points cover if it is too big (any old car/bike capacitor will do for a test)Just disconnect the one inside and connect the new one between the wire going to the points and ground. PS How's the compression? The decompression valve is working ok I suppose. Don't give up. I've threatened to burn my bike a few times but at the moment it is behaving well.

[Simplo]

Hi all, I don't think it could be an electric problem just for this reason: at the same moment I pull the choke on, the engine runs good and RMP increase without problems.
As soon as I close the choke the problem begins.
If it was an electrical problem I think the engine won't run even with choke or not.
I didn't found the complete MK carburator on Hitchcock parts list.. someone knows where it is?
Thank you!

[Presto]

I've not read all the posts here - and maybe ought not to get involved! - but have you cleaned the carb with solvent carb cleaner? I see you say you used compressed air, but if the problem is due to residue build-up in the internal passages of the carb (and it may well be) solvent carb cleaner will be needed.

[Presto]

I knew I ought not to post - scotty covered the solvent cleaner thing ages ago! But I do have a question for Simplo. You say your carb has the push-pull choke with the black plastic knob. This isn't a choke but a starter jet. Can you tell us do you pull the knob UP for starting and push the knob DOWN for running? (In other terms do you have the knob pulled UP for choke ON, and DOWN for choke OFF?)

[Adrian]

Presto,



It's a thought, but since Simplo has posted that the bike ran well BEFORE the problem started I assume he knows how to use the controls!



Simplo,



an electrical problem doesn't have to be an all-or-nothing problem, intermittent or part-failure of components or wiring connections can be just as frustrating to track down. There is a stage when something is failing but has not yet failed completely where the bike will sort of run but not well.



The 350 carburettor is listed in our hosts' on-line parts books here: http://www.hitchcocksmotorcycles.com/pa ... arburettor



At risk of being disloyal, £90+ before VAT is not the cheapest available, though.



This thread has been dragging on for a while now, and with so many posts it's easy for information to be lost.



A.

[Presto]

Ok Adrian, but if the engine beings to fail as soon as the starter jet is closed off [the plunger being pressed down and the starter jet being closed off] then the problem has to be weak fuel mixture – because nothing else is happening apart from the starting jet being closed, no change is being effected to ignition or to any other factor. All that is happening to the engine if that the amount of fuel passing through the carb has been reduced. Unless there is an almost magical coincidence occurring to some other engine event, the problem must be fuel related.

[Simplo]

Hi Presto, thank you for your reply.
Yes, the choke is ON when the tap is UP, as it always has been!
Now listen to this update:
some day ago I remembered that an Indian firend of mine living in my island has a Classic, but he purchased a 1980 350 years ago. I called him to ask if he had still the bike and if he should give me the carb to have a try.
He told me he had a spare carb he purchased in India some month ago!!!
I took it, it is a little different from mine because it has the chocke leverage instead the black cap.
I checked the float: 22mm
I checked the air screw: 1 and 1/2
I checked the needle: my needle does not fit in the main jet, so I think my needle is greater...
Neelde position: center slide
I assembled the carb: the bike runs PERFECTLY!
Ok!!
My friend told me another Indian guy was taking a plane to come here in a few days, and he told him to take a carb with him.
I retired it tis morning and just installed it.
So:
Initial condidition:
Float: 22mm
Air Screw: 1 and 1/2
Needle: absolutely same size as mine
Neelde position: lowest slide
Had a try: similar problema as my old carb, it runs with choke, but the engine does not idle without choke , even with the idle screw all turned in and, once I turn off choke, RMP increases for a few seconds, then engine turn off whatever I do with the throttle.
So I tried all 5 positions of the needle, no difference and mounted it back to center.
So I tried to act with the air screw, no difference.
Then I changed the float to 24mm.
With choke ok, without choke RPM increases, but if I open the throttle the engine does not turn off, even if it runs with many coughs and not constantly.
I changed again the float to 26mm.
It starst but does not idle and doesn't respond to throttle...
I'm really getting mad....
Is it possible that it runs with a smaller main jet even if the big onw worked perfectly for 10 years?