Engine refusing to start

[Big Nick]

well i put petrol in and after a bit of jumping up and down she ran ok on idle but when waited a bit then bilped the engin it died and now refused to start again , help please

Adm edit: split from "Re: What grease to use" and changed title to reflect content\question

[muskrat]

 G'day Nick.
Back to basics, check ign timing, sparking on both plugs, fuel to carb and not flooding, compression in both cylinders. If it's got all that it should run.
I'm guessing flooding or magneto.
Cheers

[Big Nick]

that's what is getting me , it's a new monblock and rebuild mag and i have had the head and barrels off the check all is heathy there ! but you are right back to the beginning again something obvious must be wrong.

[Triton Thrasher]

Possible candidates:

Closed fuel tap(!)

Empty or very low fuel level in tank

Fouled spark plugs, caused by rich idle setting or serious oil burning problem. See any smoke?

Kinked fuel hose

Blocked tank or carb filter gauze. Test flow out of the bottom of the carburettor.

Stuck float. Is the bush on the float hinge pin in the right place?

Correct arrangement of fibre washers (or none), at the carb feed banjo, for your year of Monobloc.

Blocked pilot jet. New Amals are notoriously full of swarf.

Oily points. Clean with a piece of paper.

Misaligned HT brush, which has been forced sideways against the slip ring and left a carbon track around it. Badly made soft brushes do same. Deceptive because both plugs will spark outside the cylinder.

[bsa-bill]

Hi Nick
I faced exactly the same after my project build,new carb and refurbished Maggie,
My conclusion is the Maggie while fine on my lower compression Flash is not up to consistent starting of the higher compression Rocket, neither was the maggie on MY flash (I swapped them over)
both refurbished at the same place (not any of our experts )
eventually fitted Pazon Electronic ignition - Walla first time starting every time (needed a good battery tho - 2 Burlen type).
Should say here I had an offer by one of our spark gurus to have my Maggie tested which I will do when time and cash allow (Kitchen refurb, Garden, Grandkids, sheds  sorted (after Kitchen refurb))
Other culprits -  the plugs - you need a good supply, modern manufacturing of plugs are designed for modern lean burn engines where a plug never can get wet hence once new plugs get wet they're gooshed for quite some time, modern fuel too is a well documented problem.
Meanwhile of course we tinker with the carb settings to try to get it running when the settings could well be correct to start with, my carb is close enough that it runs reasonable despite my tinkering but not as good as it could be I suspect.

So I echo Muskrats suggestion but try to concentrate on one aspect at a time to avoid frying pan - fire scenario

[A10 JWO]

I would go for that green slim in the carb building up in the primary if all else fails. Good luck.

Colin

[Lord Flashheart]

Hi Nick
It would seem this is not an uncommon problem with re-builds. I wouldn't pretend to have all the answers, ( though I do share your problem), but my research has uncovered some interesting comments which you may choose to explore.
I experienced precisely the same 'run, stutter and cut' scenario' on my first start-up.  I would have been convinced it was a fuelling problem. My tank was running low, I knew the carb needed re-sleeving or replacing, she was running very rich and I could not correct that.
But after she stuttered to a stop, I checked the plugs ( a new set) to find them quite black and sooty, but more painfully - without a spark, even after cleaning !
I then discovered that I was running the wrong plug ( a box came with the bike e so I assumed they were OK ) --- They were suppressed plugs, and I was using suppressed caps. Either can weaken, but BOTH certainly will, kill the spark (I'm told).
However, with plugs and caps removed I find no hint of a spark between lead-end and cylinder head.
I'm running a B.Bransden ignition, so was most surprised to find this, I'm in the process of getting it checked-out.

In your case Nick, the finger of suspicion could be pointed toward another factor: Previous posts have suggest that inlet tract obstruction,particularly along the base of the tract where the atomised fuel flows, can destroy atomisation, cause apparent enrichment, and destroy plugs through irreversible contamination. (Efinol fuels being contributory.)  -- So check for steps at the flange, a mm. or less can be problematic. !  Engines like ours,and modern (new) unglazed insulator tips  are not happy 'bedfellows' --- It seems !
The advice, ----- get lots of plugs and keep changing them or run a 'used' plug, (more tolerant) while you're fixing the other problems.   
Not my wisdoms I hasten, but all sound plausible.
Happy days 
Flash'  (Pete)

[Billybream]

Hi Nick.
Could it be stale fuel, also try pre-warming the spark plugs.

[Topdad]

Nick, think we are all being to helpful with ideas that could be stopping us see the wood for the trees !
Go back to the first post by musky , it's got to be either ,mechanical,electrical,fuel or unusually the exhaust.
So if no sparks check your system ,you don't say but if magneto get the points out ,clean 'em on a stone ,gap em .  then examine the pick up carbon bushes ,are they moving easily and enough meat to run on the slip ring . Clean the slip ring  check it for cracks etc. check the leads ,are they wire or carbon if carbon insert in bin and get new ones likewise if showing there age leave the maggy end cap off it may be shorting to earth,when you've done that with plugs out check for a spark. I Assume you'll have new plugs . if it sparks great if not check connections if still nothing a bit brutal ( for you ) take out an ht connector at the mag stick your finger in and kick hard if you get a whack you now its doing something and work back from there ,DON'T do this if you a heart problem or a pacemaker . In that case get another person to do it for ,tell'em it won't hurt !!  Just thought ,check the points aren't arking, we had a post a little while ago where that happened, think part of the points touched the cam ring as it spun.Once you have a spark check the timing rocker covers off ,valves on relevant pot rocking  pencil down plug hole check 5/16 BTC  ,a fag paper between points gap should just be releasing grip .If sparking and you're happy with the timing time to move on if still no spark whizz off mag and send to expert to get it sorted many names available here who can be trusted. Once the maggy eliminated recheck other component parts ie the carb and fuel flow and finally check tappets and confirm compression ,even by just putting finger over plug hole if it's okay replace plugs and hopefully it'll run.Stay positive and work through everything and it must go  ,best of luck , BobH

[chaterlea25]

Hi All,
Another consideration since the top end has just been assembled could be misplaced pushrods??
then it may have fired up just long enough for them/it to jump out of place 

HTH
John

[wilko]

A couple of new plugs and a can of Aerostart should sort it out!

[Big Nick]

thanks for all the advice , but still no joy , carb apart and cant see any problem i did swap the pilot jet for at 30 to 25 and check the needle was in the second position , i am using un-supressed plug caps . the flue is new , no blockage in flue lines . the clutch was slipping so i tough maybe just not enough boot so all apart cleaned clutch plate no slip but still not running .

[Big Nick]

can not see swarf in pilot jet hole , my next step i think is to find the concentric the bike used to run on and put that back on

[Big Nick]

i did also double check the timing , i have one of those electonic points checking things for magnetos

[Big Nick]

the one thing i keep on thing is i have time it past tdc not before tdc so check that again !