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[hkbulleteer]

Hi all,

I joined the Enfield fraternity recently, bought a 2001 Bullet 500. Great looking maching but since I’ve had it, I’ve struggled to get it to run right, so hoping the wisdom of the group can help.

Air filter as per attached.

Exhaust: short pipe (Jidori?) also as per attached. Pretty noisy. Looks adulterated but being unfamiliar with these bikes, I don’t know if a baffle might have been removed (that said, I can’t see how!). Muffler length 23”, 48 mm opening. I don’t believe in loud pipes, Ibut rather in getting on with my fellow man and woman! Any ideas for a quieter pipe gladly taken. Tried a £7 DB killer, no change, if anything made it a bit more shrill.

Amal Mk1 Conc carb R300/930. Main jet is 220 (the previous owner had a 300 at one stage), needle jet: 107 - as far as I can tell, both genuine Amal. Pilot jet- confused on this point. I think some Mk1s have pilot jets that screw in, other are pushed in and hidden somewhere and only come in one size? Either way, I can’t see one.

Slide is 3.5 - but also marked 928 if that’s relevant? Would it be shorter than a 930 slide...?

When it's running, it goes ok. Inconsistent in starting. Of late not at all.
Never idles steady - always have to hold the throttle at traffic lights in case is splutters and cuts out.
Mechanic (who’s knowledgeable about old bikes) says I need a bigger slide (4 or 4.5) to lean it out. From your info, I’d have thought the problem is on the pilot circuit. Unfortunately, that’s the one I’m confused about how it’s jetted. He’s a good guy, but doesn’t have much time to go down this rabbit hole and parts aren't readily available in Hong Kong, so up to me to figure this all out.

Other than that, combustion chamber is pretty coked up. Within a 100km the new spark plug is filthy black, so it seems I’ve running very rich.

Any advice greatly appreciated. Happy to buy a whole new carb and a sensible spread of jets and start at square one if that’s the answer and ditch this mess. Just need recommendations on jet sizing from someone who knows these bikes.
Would changing to the original exhaust need different jets? Again, not a lot to choose from locally, so need to order this in from UK/India too.

Thanks in advance!

[stinkwheel]

Is the float bowl filling properly (does it overspill when tickled)? Both Amal Mk1 carbs I've had had occasional episodes of not filling for whatever reason. I sometimes land up blowing down the fuel hose, then reconnecting it, then tickling.

One suggestion would be that you can pick up a used mikcarb for sweetie money on online auction sites. If nothing else, their starting and idle performance is usually excellent.

[hkbulleteer]

thanks stinkwheel. I've the opposite. More recently the float bowl seems to be overfilling, nOthing impeding the float coming up as far as I can tell (e.g. gasket). Really not having much luck with this carb. But hitchcock's wrote back and recommended a stock exhaust, a number 3 slide and a 106 needle jet and 20 0 main. Might just do that and start at the beginning again!

[windmill john]

Interesting. Another chap on this site had issues with his mk1 concentric 900/930.

He changed carbs and I bought his 900/930 at a very good price to see if I could resolve the issue. I was getting a bit frustrated with my monobloc. However, I’ve persevered with my monobloc, so did not try the mk1 properly; that didn’t help you did it!

Purely as an aside, I did try the mk1 on my 350 bullet and it revved very high at idle. So I ordered a smaller slide. I just haven’t tried it yet sorry.

[Andy C]

Believe that a 106 needle jet is standard for these carbs and a 107 is probably too large, but it should not make a lot of difference to your slow running.

If you are suffering a sooty plug / poor starting I would check the float height in the carb, and make sure that the float is not punctured, pretty sure that in the MK1 carb the pilot jet is not removable.

Take a look at this guide to setting float height: http://amalcarb.co.uk/optimising-mark-1 ... uel-levels - hope our hosts dont mind me posting that link.

I would also take the air screw out and blow through the carb body - there could be something caught in there, does turning the air screw make any difference? the baseline setting for the screw is 1.5 turns out.

Are you sure it is a 4 stroke carb? You can tell by looking in the carb body (from the engine side), if the tube into which the needle drops is cut away on that side it is a 2 stroke carb.

Finally is the filter element clear?

I have had 2 bullets with Amal MK1's fitted to them, and never had any issues once setup. Tried an Amal Premier once and could not get the bike to run.

[hkbulleteer]

cheers Andy, John,
I ended up ordering a new 4-stroke carb from Hitchcocks and will do some experimenting. I think the float height was definitely one issue, I couldn't see a hole in the float, but it's one of the old ones with plastic tangs so can't really adjust it either. The new one will have the metal tangs. Also ordered a stock exhaust. Once it all arrives, will bolt it all together and see if that works. Dug out a Gunson colour tune kit that I bought for an XS revuild years ago and never used
You're right on the pilot, it's a little brass insert that you can see when you peer down the hole that the air screw sits in, so at least it's there
Now over to the SV forum to figure out why that old unit doesn't start!
thanks for the feedback, great to have a forum like this to fall back on.

[stinkwheel]

SVs like to collect water and corrosion in and around the front sparkplug and HT lead area.

[p]

Simple way to check float, submerge it in warm/hot water - it will blow bubbles if it has a leak.

[Lou E]

Here in USSA we have corn alcohol in our "fuel". Jf for any reason you get a drop of water in the AMAL it may migrate to the cross drillong in the needle jet. Remove the bowl and jetholder, hold the needle jet up to the light and if there is a drop of water in there (it has a higher surface tension than gasoline) blow it out and the rich condition should be rectified. (you get extra points if you have to do this on a Trident!)

[Beezabryan]

HKBulleteer said -
"Other than that, combustion chamber is pretty coked up. Within a 100km the new spark plug is filthy black, so it seems I’ve running very rich."

Decoke the head & piston crown is the first thing I would do, before spending money and time elsewhere.
Filthy black plug? with the coked up combustion chamber that could well be oil contamination. Worn valve guides and/or worn bore and/ or piston rings. These things are what i would check.
As for "Mechanic (who’s knowledgeable about old bikes)" ? No comment.

Just my thoughts, others may or may not agree.