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[Exile]

Norm: The jets are all brand spanking new. I rejetted after fitting the new S&B air filter, which just about everybody here said I should because the engine would otherwise run lean and the guy from Hitchcocks helped me with that.

It ran (sort of) OK after that but it is, and was, running rich. If you don't count replacing a torn manifold rubber, which should have made it leaner anyway, as critical, then how else do I get it to run a little run a little more lean? Playing with the air screw and throttle stop doesn't cut the mustard.

Could it be, that the fuel mix that the PAV (now removed) was 'stealing' from the total fuel supply is making a difference now?



I will move the needle stop back to where it was. If, as you say, it makes no difference, then I have gained nothing there anyway.

Pony, another forum member, is having the same problem as I, having done the same mod as I did.


1. Fit S&B filter.

2. Rejetting the carb. as per Hitchcocks recommendations.

3. Remove the PAV.


Results in both cases are the same. Rich mix.

We're both stumped.

[PeteF]

Just to check....
You do realise that the choke lever is Up for normal running, DOWN for choke.
Just checking! You wouldn't be the first to mix that up.

2500 miles is quite enough to need the valve clearances adjusting, though it wouldn't account for the rich running, it would account for the spitting back and general poor running.
"Timing was OK before rejetting" well, yes, but it might be out just by sod's law. Worth checking as this would cause the spitting back as well.

[Pony]

Yep, having the same problem. Put a colourtune in place of the spark plug and watched the burn. It's bright orange right through the full range of adjustment of the mixture screw, so very rich. Weird thing is that following the carb tune directions in the technical notes, I set the throttle stop for fast idle and when I wound out the mixture screw (which I think makes it even richer? please correct me if I'm wrong) the engine speed picks up all the way to the point where there is no more thread on the mixture screw. Bright orange flame all the way through. Looks like the recommended jet and slide sizes in the Hitchcocks (same advice over the phone) may be wrong!

[Norm]

Exile,put the original jets back in and see what happen then, there is no hard and fast rules with Enfields, what works on one often doesn't with another. I checked the main jet on a bike that I know has been ridden long distances with the throttle wide open and it has a 117.5 main jet in it, in theory should have holed a piston years ago, pulled the top of the piston a few years back but that wasn't as a result of running lean

[Exile]

OK Norm. I'll put the throttle needle back where it was and rejet to the original. I'm going to be busy with a few other projects until tuesday but may be able to get to it then.

Thanks for chiming in mate. You have a wealth of experience that I'll never achieve.. so I'll give it a go.


If Pony is following this, and I think he is, then he may beat me to it. If so, I'll be waiting for his response to all of this.

[Exile]

Perhaps I should mention, jetting now is:

Main: 117,5

Needle jet: P0

Pilot: 27,5

[Nettshubby]

My sixty5 had same trouble, could start it on starter, but trying to pull away it would spit and fart, try to cut out, and would only run something like if choke was on.

Contrary to opinion, i moved the needle clip to bottom position and, voala, it now picks up and runs fine.

I havn't checked needle jet size, as really the needle shouldn't have to be on max rich setting. Will try one notch higher, and maybe fit 2.5 slide, it has 3 in at moment, standard one.

Ray.

[Nettshubby]

Pony, mixture screw is an air screw, turning it out weakens tickover mixture.

Ray.

[Gwilly]

Exile forget the PAV, its gone and as long as the vacuum tube from the inlet manifold has been securely blanked off then will cause no problem..

I think the S+B filter is suspect and may not draw as much air as advertised.. Its heresay but i've read that others have had problems with this filter on there enfields..

The jetting you have is the same as mine, running an open loudner but mine still has the original type round filter in the tool box>= perfect mixture+ plug colour…

A rule of thumb with the micarb, if your turning the air screw OUT by more than two full turns from fully IN to get a half decent tickover then its probable you have a restricted air flow, and/or your pilot jet is too big for the application/set up.. Either try the old filter temporary, or lower the pilot size to match filter…

As has been said float height is important and must be checked but is unlikely to have changed in the normal course of jet fiddling..

Check the small orifice/air intake for the pilot is clear by squirting carb cleaner in the hole (filter end) with the air screw loosened off but not removed… should see fluid erupt from the groove in front of the carb slide…. Don't fiddle with timing etc until your sure carb is right. one job at a time or you get yourself further into the mire… gwilly..

[Exile]

@ Gwilly and Norm.


It rained here today so my new roof on the shed project went tits up for today. Meteorologist = Compulsive liar.


So.. being a bit bloody minded about everything, I went back to my carburettor problems.


Norm:

I moved the needle stop back to the original placing. Being a pedantic old git, I put the carby back together and looked at my notes (yes, I keep notes) from the last rejetting and the subsequent road test. I noted that it had all gone well. I set the air screw as I had it then (1 & 3/4 turns out) and kicked him over. Vroom - vroom. No coughing, spluttering, farting or cut outs. Throttle is responsive with no problems and it revs up smoothly from idle to high revs. For the moment, I'm gonna leave him there. At least I can ride the bike now.


Gwilly:

Thanks for clearing up the PAV question. I had thought of putting the (smaller) original pilot jet back in as that would reduce the fuel flow at idle but I would still have the advantage of the larger main jet at the top end. Reading through the Micarb tuning manual indicates that may be a solution but there is nothing hard and fast to read in that publication concerning this particular 'problem'. I might just try it though, mainly because I'm a stubborn old Mendips yokel with a highly developed inquisitive streak...


Here endeth the umpteenth lesson. I'm off to the pub.