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AMAL 626

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AMAL 626
Started at 02:50pm on the 31st December, 2018 by BASIL
BASIL Subject: AMAL 626
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.
Posted: 02:50pm 31st December, 2018
Presto Subject: AMAL 626
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).
Posted: 08:32am 2nd January, 2019
stinkwheel Subject: AMAL 626
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.

Posted: 12:15pm 2nd January, 2019
Presto Subject: AMAL 626
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!
Posted: 01:00pm 2nd January, 2019
Aethelric Subject: AMAL 626
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.
Posted: 01:27pm 2nd January, 2019
stinkwheel Subject: AMAL 626
Clearly me using it wrong then.
Posted: 01:56pm 2nd January, 2019
Presto Subject: AMAL 626
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.
Posted: 02:45pm 2nd January, 2019
PeteF Subject: AMAL 626
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 😉
Posted: 03:09pm 2nd January, 2019
John L Subject: AMAL 626
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)?
Posted: 04:32pm 2nd January, 2019
John L Subject: AMAL 626
stinkwheel - OK we've seen your Amal slide - now show us yer flange.........
Posted: 05:13pm 2nd January, 2019
Beezabryan Subject: AMAL 626
Always go for the most expensive cure for an easily rectified defect, you know it makes sense
Posted: 07:08pm 2nd January, 2019
stinkwheel Subject: AMAL 626
Huh, huh. Flange.

Posted: 07:20pm 2nd January, 2019
nab301 Subject: AMAL 626
I fitted an Amal to a 350 I had back in the noughties.. It had the jet settings as above ( I still have the carb but not the 350). It suffered horrendous slide wear similar to the photos . It worked fine and I liked the tickler ( easy to know if there's petrol in the float bowl). Difficult starting one day I diagnosed blocked idle passage , I was unable to clear, refitted the original Mikarb , wasn't late for the meet up I had planned and the bike ran fine from then on . I guess I had more money than sense at the time ! Although it didn't stop me buying a MK2 for my current 500...( I like the looks)
Posted: 09:05pm 2nd January, 2019
Adrian Subject: AMAL 626
The original Mk1 Concentrics were the result of the 60s British bike manufacturers screwing Amal down on price, with the fairly recent introduction of the Premier by Burlen Fuel Systems (the current producer of Amal carbs) being an attempt to right a few of the wrongs of 50 years ago. Pub quiz question, which was the first British motorcycle to be fitted with the Mk1 Concentric?

I'm sure Bullet Whisperer won't mind me re-posting his video on how to clear the (non-Premier) Mk1 Concentric pilot jets.

Posted: 09:51pm 2nd January, 2019
mauri Subject: AMAL 626

or you can just a easily take te plug out in the back, and get a nice clean view of the channel.

Image and video hosting by TinyPic

Posted: 11:53am 3rd January, 2019
Bullet Whisperer Subject: AMAL 626
Posted: 12:22pm 3rd January, 2019
Super45 Subject: AMAL 626
The slide sticks on my 350 mikarb, always at the top of the slide and it will do it with or without the carb top in situe, I tried a bit of abrasive paste in the bore and on the slide itsself to no marjoe benifi so have come to the conclusion the carb potentially has warped by over tightening by previously hamfisted owners ( many owners with little mechanical knowledge me things judging by the state of the clutch i replaced the other day) , so will try the little chamfer as suggested above to see if that works but may invest in a full rebuild kit as it decided to piddle fuel out of the side float chmber bottom the other day when i tried to start her so mor investigation is required me thinks
Posted: 11:12am 7th January, 2019
Mark M Subject: AMAL 626
Adrian, what's the answer!

REgards, Mark
Posted: 11:39am 7th January, 2019
John L Subject: AMAL 626
Amal 626 fitted to my Bullet 350 :-" alt="Bullet-350-with-Concentric-carb-and-homemade-cables
Posted: 01:17pm 8th January, 2019
John L Subject: AMAL 626
stinkwheel - Your experience with Amal carb. - you say "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".,br> Had none of that trouble myself - I've made all the cables on this bike. Throttle cable too long ? well, shorten it ...!
Too long, too short, I'd have only myself to blame.
I can't see anything difficult about routing air cable, either. Maybe carb. position is different on your bike ?
Posted: 01:38pm 8th January, 2019

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