Will not run

[Minto]

I'm on the verge of using bad language at it now. Desperation doesn't do justice to how I feel.
Since putting the engine back together with new pistons, new main bearing, new big end shells and a few other wee bits, I initially had it running without the silencers, though only for a very short time and I hadn't tried revving it at that point. After that I put the silencers and all the other bits back on, and though it did start it spluttered and spat back through the carb when ever I touched the throttle.
I've stripped the carb since and blown through all the jets, (276 pre monoblock) including the idle circuit which doesn't appear to be blocked judging by the carb cleaner issuing from the pilot jet when squirted through the hole on the bottom of the jet block.
I've had a week away from it until this morning, when after a suggestion from Swarfy I checked that all of the pushrods were seated properly (in the followers and in the rockers) which they are.
I've also took the carb off again to check needle position (2nd from top, it's a number 6 needle)
I've also checked the ignition timing again, and re set it with a 0.0015 feeler blade at 11/32 btdc fully advanced and the points were set at 12 thou before hand.
I can get nothing out of it, not a glimmer of life. I've kicked it til I couldn't breath anymore. I've checked that there is good spark on both sides.
While trying to recover from kicking it over and over I had a look at the throttle slide opening and closing on the twist grip, which didn't seem to be returning fully, though it's hard to get a decent view of this as it's so close to the frame down tube.
Any suggestions on what the hell I've done wrong to deserve this would be welcomed. I'm kind of disheartened to say the least. Big problem I have is a lack of time to work on it, three hours this morning was a rarity, I might get a couple of hours tomorrow or Wednesday but that'll be it for another week.
Here's a link to a video of it running without silencers..
https://youtu.be/ctu-PS1AJ3Y

Please help!!!!
Thanks
Jase

[RDfella]

Tried swapping the plug leads? Is the fuel fresh (ie not more than a couple of months old? Does the carb fill with petrol? Sure the timing is BTDC and not ATDC - not a common mistake but has been done - DAMHIK).

[Greybeard]

When I swapped my HT leads over by mistake the engine just popped and coughed occasionally but would not run. It sounds like your bike runs but stops when you open the throttle; is that the case?

[Minto]

Cheers RD, I'm going to recheck all of your suggestions tomorrow, was going to check some of hat today today but ran out of time.
The possibility of it being timed ATDC would definitely explain things and is a possibility as by the time I redid the timing I was very aware of the time so maybe rushing a bit.
Jase

[Minto]

GB, things have took a turn for the worse since then, the damn thing is showing no signs of firing at all now.
Jase

[Greybeard]

GB, things have took a turn for the worse since then, the damn thing is showing no signs of firing at all now.
Jase

Well, it's pretty easy to get the mag connections wrong. Might be worth swapping the leads over.
If that turns out to be the problem I promise not to point at you and laugh, because I've done it and so have most of us here.  🤞

[Minto]

Hopefully Mrs Minto has no plans for me before work tomorrow and I'll get chance to investigate.
Working for a living don't half get in the way of the important stuff.
Jase

[Roger (Doomtrainbarx)]

If the plugs are wet -  you've got fuel
You know you have a spark
You should have compression  after the rebuild (check to be sure) -  if you have all 3 elements the only thing stopping it running would  be the timing not set right.

[BagONails]

Been there before, can be frustrating!

This is a bit more work but worth it if you can find the problem.  I would consider fitting a timing disc to the crank and a fixed pointer.  Find TDC as accurately as possible (piston bump height) Then check through all your valve timing, opening and closing then the ignition timing, rig up a separate battery and bulb across the points. If all good then it must be either compression or fuel related. But if you are not getting any signs of life now after it was at least running it sounds like something has moved or changed in some way...Good luck!

[Minto]

That Roger is a good point, for the amount of times I kicked it over when I took the plugs out they weren't noticeably wet.
Cheers
Jase

[Minto]

Well there's definitely compression, my right leg can attest to it.

Valve timing should be fine, I remember taking a pic of the marks all lined up before the inner timing cover went on, and I've checked the order of them opening and closing as I've turned it over when the tappet covers were off earlier.

So its fuel or sparks.
There's something dodgy with the throttle slide not returning so the carbs gotta come off anyway so may as well start there.

Thanks everyone for your suggestions and help.
I'll report back on any progress.
Jase

[Minto]

Only managed a 15 minute mess about this morning, but took the carb off and hopefully sorted the sticking throttle slide, and raised the needle a notch.
Also had a quick look at the ignition timing, with the timing side piston 11/32 before TDC  on the comp stroke the points fully advanced were still closed, turned the engine forward through TDC to 11/32 after and hey presto 1.5 thou blade slides out. Thanks for that suggestion RD Fella, haven't had time to rectify that today but I dare say it'll improve matters when I do.
Ok now point and laugh!
I'll let you know if and how it goes when I get chance to redo it
Thanks all again, great forum this.
Jase

[RDfella]

Easy mistake to make.
My first bike was an ML James when I was about 15. Every evening after school I'd remove the flywheel, replace it so the points were closing just before TDC and try to start it. Nothing. I'd do that perhaps half a dozen times each day (for more days than I care to remember) until one day it burst into life. I was really excited. Turned out I had actually set the timing right by mistake - at 15 I'd presumed the spark was sent to the plug when the points closed. I know better now.

[Minto]

"Easy mistake to make"
Yes, if you're me!

I was starting to run out of time (and the will to live) by the time I reset the timing yesterday. Hopefully I'll get to have a crack at it tomorrow. Fingers crossed.

Thanks again
Jase

[Swarfcut]

Jase. All engine problems are down to mechanical, ignition and fuel. For a non runner you can forget fuel, and  assume its mechanically OK. Then its a matter of good sparks in the right place. A prime of the cylinders with a good dose "down the hole" and it should at least fire. Then you can play with the carb if you get some attempt at life. Still no joy? Basic mechanical checks and another good look at the ignition.

Swarfy.

PS Don't top yourself...end of lockdown soon (or not)