Forum

[BASIL]

Hi, I am going to try an Amal 626 carb on my 350 Bullet can anyone tell me what jets, needle, needle jet and slide size I need the bike has an Goldstar type fairly open exhaust on it, My problem with the Mikcarb is the slide keeps jamming open, a bit disconcerting to say the least. Thanks in advance, regards Basil.

[Presto]

As a starting point for fine tuning jetting close to this may be ok - 160 main jet, 106 needle jet, 3 1/2 slide and (17 pilot if it's a Premier version of the carb).

[stinkwheel]

I'll say this here and now. I have had nothing but problems since fitting an Amal carb on my 350 bullet. The slow running circuit is prone to gumming up meaning it needs regular stripping and cleaning. The float height randomly alters itself and seems to randomly stick. The choke cable is, as well as being seemingly redundant, difficult to route, fussy to locate and prone to seizing. The throttle cable you get with them is always too long. If it doesn't have a hardened throttle slide, it will wear both the slide and the body to the point of uselessness after about 20k miles.



I just put the original mikcarb back on mine at the weekend and it now starts first kick, idles nicely and runs much better. I'm missing a tiny bit of top-end but the gains elsewhere more than make up for it. i'm wondering why I didn't do it sooner.



I had a mikcarb slide start sticking years back, often at the top of the travel. It was a richer slide and on comparison with the original, it was missing a slight (maybe 2mm) chamfer around the top edge of the casting. I put one on with a bit of emery cloth and it sorted out the problem. This would have no affect on the actual function of the component.



The one on the right is the original slide. The one on the left is the one that was sticking, you can see where I have put the chanfer on it. Pretty sure it was jamming in/on the flat rubber o-ring on the inside of the carb lid.

[Presto]

It’s not unusual to hear critical comments about MK1 Concentrics. But the fact is that 1000s of these are fitted to 1000s of engines and run perfectly well. Clearly if the bike isn’t running well then the carburation fault needs to be corrected. But this is an anomaly and not a fundamental fault. The criticisms of these carbs is almost all theoretical and ignores the incontestable fact that they work well in all types of engines and have done for over 50 years!

[Aethelric]

My Mikcarb used to jam open. The previous owner said it was OK as long as the top was not tightened down hard. Fortunately I was given a spare on with the bike. When I compared them both, the one fitted had a thicker O ring sealing the top. As the top comes down it should push the O ring OUT but it can simply compress so that the slide sticks in it at the top of the travel.

I found that the thinner O ring was OK, but with a bit of silicon grease, the thicker one would fit in position OK as well.



Before I sussed this, it was a twitchy job slackening of the top far enough to stop it sticking but not far enough to have it coming of the spigot and, of course, sticking open.



I have nothing to compare it against, but the Mikcarb seems fine to me.

[stinkwheel]

Clearly me using it wrong then.

[Presto]

The wear on that slide is obviously excessive. What has caused this excessive wear I don't know. While it has been long recognized that the Mk1 slides wear being in contact with material of similar type - hence the availability of harden anodized options - the wear seen on the photo is excessive and not normal.

[PeteF]

Fit an Amal if you like but there's nothing wrong with a Mikarb. It might be easier to find out why yours is sticking and fix it. If not there's plenty of used ones on eBay from folks that's fitted Amals 😉

[John L]

Basil - As no one else has asked - New Amal, standard or Premier version ? Secondhand Amal, source and condition ?

Bullet 350, Indian or Redditch version ?

If you are unable to fix the sticking problem with the Mikcarb, would you able to fix a similar problem with a Concentric (an unfortunate possibility with a typical used instrument)?

[John L]

stinkwheel - OK we've seen your Amal slide - now show us yer flange.........