Hitchcocks Forum

I'm sure this had been done to death, but looking back only saw thread for some new premiers.

My bike has an Amal Monobloc. Generally it has been very good, but this morning.... I decided to collect a pound from everyone for each kick to try and start it. So far I have bought two Maseratis and a small island in the Caribbean.

Bike had been stood a week, I normally get out on it more often. But now that Ari has arrived, my 500 Classic, I rotate my riding. I'm guessing damp possibly, bike was wet under cover, but tappets good, new plug and cap.. and coil.

Tried all starting variations, including the last resort, fast re-kicking shouting start you bugger!

Just thinking ahead to next year, can you suggest a couple of alternative carbs?

Thanks

John

If it has been OK but now won't let you start the bike for some reason, has some bit of dirt found its way into the pilot jet or its environs? Be thankful it's not a concentric. Try and get it working before shelling out for a replacement.

You checked that there was a good spark, new electrics notwithstanding, maybe a duff/counterfeit NGK plug? Champion recommended.

Alternative carbs? I've heard good reports about the Wassell clones of the 26mm Amal Mk1 from one of the regulars here (keep that pilot jet clean!). Another good choice would be a genuine VM26 Mikuni. Also consider a PHBH26 Dell'Orto.

A.

I doubt if it needs a new carb. It’s not very often that the carb itself – rather than its condition – is the root cause of poor starting. A new carb is simply the same again jetted right and clean.

A carb body doesn’t in itself result in poor starting – only its condition or set-up. Solvent spray carb cleaner can work miracles with ethanol contaminated carbs.

I don’t buy into the idea that the AMAL Concentric is a liability. Countless 1,000s are running perfectly. If you must replace your carb an AMAL Concentric Premier would be the obvious and most cost-effective choice. (There’s something definitely Kafkaesque about recommending a Wassell clone over an AMAL!)

Adrian wrote: ↑

Mon Aug 17, 2020 1:19 pm

If it has been OK but now won't let you start the bike for some reason, has some bit of dirt found its way into the pilot jet or its environs? Be thankful it's not a concentric. Try and get it working before shelling out for a replacement. Oh don't worry, it would be a last resort

You checked that there was a good spark, new electrics notwithstanding, maybe a duff/counterfeit NGK plug? Champion recommended. I'd be telling off our hosts if it's fake!

Alternative carbs? I've heard good reports about the Wassell clones of the 26mm Amal Mk1 from one of the regulars here (keep that pilot jet clean!). Another good choice would be a genuine VM26 Mikuni. Also consider a PHBH26 Dell'Orto.

A.

Thanks both. Carb cleaned last month, new gaskets etc.

My bike starts and runs far better (including a higher top speed) since I fitted the Wassell 26mm concentric with the inlet port opened out to suit it. It came with a stub stack inlet trumpet which I retained by fitting a pit bike oiled foam filter over it. I can’t say if a duff carb actually explains your starting problem, though.

Adrian, I’m hopefully keeping the pilot jet fuel insert clear by use of a fuel tap with a strainer, an in line fuel filter and the air passages clean by use of said air filter.

Interesting post , maybe scrap the bike and use one of the Maseratis.

Being a technical post I can only suggest you try sacrificing a small helpless fury type animal at midnight.

Might work.

Well, I think Gupta got hold of my laptop whilst work, read this thread, felt so bad, that when I came out after work, he started first kick.

Difference? They all could be red herrings, but bike was damp, carb could have run dry due to the heat this last week and maybe the float was stuck; he was exposed to full sun all day, albeit under a cover. Maybe my starting technique varies too much.

Still, I’m home, great run, may swap one of the Maseratis for a Wassell.

Mine starts and idles SO much better with the original mikcarb that I put it back on for use as a trials bike. They have a proper slow running circuit.

Don't know about the monoblocks but on MK1 concentrics, the starting and idle circuits seem like a total lash-up from the design stage onwards. They took a simple idea and executed it in a manner that seems almost wantonly over-complex and prone to failure. From the "hidden" drillings and jets right up to the abortion of a contraption that is the bar-cluttering, cable-controlled, self-applying choke.

So, you could get a mikcarb for sweetie money. Re-brassing them with japanese spec brass makes them even sweeter. Or get a proper Mikuni. Even RE, when given the option for manfacturing their own carb, under licence, went for the mikuni.

I could just about convince myself that it had a miniscule amount more top-end with the 28mm amal (ported head fitted) but the ability to start first kick, transition xsmoothly onto the main jet and also to shut the throttle and have it idle properly every time cancells this out.

I briefly messed with fitting a VM28 mikcarb to it, found a proper manifold and everything. It starts and idles fantastically but I struggled to get it set up for WOT running, just lots of bogging/stuttering. Probably more a matter of time and some fresh jets (it was second hand) than a fundamental problem. The fitting is a mikuni plate manifold part number: PM01-K. You need to use socket head cap screws to fit it because there isn't room for a hex (might manage an allen head sleeve nut if you want to retain studs).

Thanks Stinkwheel. I found today I was getting the same little phut at tickover I had with my old silencer, before I tweaked the idle mixture. But I’ve had this new silencer a couple of weeks or so. So just played with my Colortune again; we’ll see.

I removed the choke mechanism from my Wassell because the bike starts first kick without it, just tickling the float does the job.