Damn bike won't start!

B-Stone · Apr 25, 2009

After dropping a carb bowl and trashing a piston, I took the beats head off and had her rebuilt. Put new pistons rigns etc and re-assembled now that the weather isn't sub-thermal any longer.

The big day came and after approximately 3000+ kicks, I can't get her to turn over!!!

It comes close every 15th kick or so but the majority just feel like a dead kick. I get the odd pop and kick back periodically.

Battery is charged up, re-checked the Boyer wiring and all seems on the up and up. The carbs were rebuilt and seem to be functioning A-OK.

So....

1. Could the Boyer be acting up and if so;
2. Any simple checks to see if it is fried?

I was also wondering if maybe I didn't ground the Boyer well enough? (It is between the head steady bracket and the cylinder head.

Thanks

B-Stone

cash · Apr 26, 2009

You'll get the fault finding note here http://www.boyerbransden.com

Try checking you've timed it on the correct rotor mark ie TDC not BDC and the Boyer stator coil wires aren't crossed over.

It's usually something stupid.

Best of luck
Cash

ML · Apr 26, 2009

I find the best thing to do in these situation is to remove the spark plugs, connect them back onto their coil HT leads, lay them down on the head so they don't roll around and with the electrodes visible. If you can do this in a dark place, i.e. lights out in your workshop, then make sure the fuel taps are off and turn the ignition on and kick over the engine and see if there is a good visible spark at the plugs.

If you have compression, fuel and spark it should start. If not, its likey the timing is way out.

Mick

B-Stone · Apr 26, 2009

Great link Cash. I am a complete idiot on all things electrical and that tech page has some plain speak easy checks.

I did confirm that it is sparking with the key switched on. Will walk through the sheets checks.

The bike had been wired pretty strange by the previous owner some time ago. I had it running good (less the rattle of the one piston) prior to doing the top end.

I am wondering if I have re-wired the boyer differently than he had it although I am using the Old Britts wiring diagram.

Thanks again guys...I guess it will have to be the BSA in the meantime!

B-Stone

B-Stone · Apr 26, 2009

Boyers seem functional and is wired correctly according to the Boyer manual.

After about 6 kicks I will get a sputter and it will almost turn over. Next kick, again will almost start.

Then it is back to 6-10 more kicks with nothing before it will sputter again.

Have tried no prime and full prime and got an awful sore foot now from several wicked kickbacks.

The bike was running well before teardown and I have not moved the stator.

Is it possible that the bike was wired with positive ground? If so, would appreciate if someone can tell me how I can tell.

Thanks again

The electronically confused B-Stone.

swooshdave · Apr 26, 2009

B-Stone said:
Is it possible that the bike was wired with positive ground? If so, would appreciate if someone can tell me how I can tell.

Thanks again

The electronically confused B-Stone.

Usually you can tell by which wire is on which battery terminal.

blaisestation · Apr 27, 2009

Hi nortons originly have positve earth !

grandpaul · Apr 27, 2009

All Norton Commandos were POSITIVE ground, but that doesn't mean it might not've been reversed at some point in time.

You say you didn't futz with the ignition stator and/or rotor?

That leaves only the wiring, and/or your valve lash adjustment is off.

B-Stone · Apr 27, 2009

Well the previous owner had some creative wiring going on so the colour of the wires are not always text book. Having said this, I am 90% sure the boyers are fine and the stator was not messed with. Fro what I can trace (without unwrapping his custon e-tape wraps) it is pos ground.

As it almost seems to go on ever 7-8 kick and has kicked me a couple of times, I am thinking the lash is off or god forbid the push rods are messed up/not correctly seated.

Everything seemed to check out when I hand carnked it over after putting the head on and I did set the valve lash but I guess it goes back to the what did I last F*** with!

Back to the garage I go. Thanks for the tips and will let you know what I find!

cash · Apr 27, 2009

It might not be electrical try ;
A couple of kicks with the throttle wide open ignition off. switch on and try as normal.
Try starting with the throttle half open.
Check you are getting fuel into the carbs.
Fit new plugs or at the least clean and gap them (carbon fouling) and try again.
Cash

Cookie · Apr 27, 2009

A compression test should show you if the lash is too tight. I'd sure suspect electrical as you should be able to easily test for gas by inserting a bit of gas directly.
What happens if you reverse the battery connection on a Boyer wired the other way? It sounds like he is getting a random spark which could easily be bad ground or a bad connection. The ground would be easy to test by running a test lead from the battery ground to the Boyer ground.

B-Stone · Apr 27, 2009

Award for Norton Dumb-ass now in

OK, so shot the compression and the one cylinder was ZERO!!!!

After hours of messing with poor old mister boyer, it appears it was none other than yours truly setting a really bad lash. I don't remember being drunk that day but the clearances were way off when I checked them tonight. Reset them and left jug was responding pressure wise quite nicely.

Will head back out shortly once my wife takes off my shock collar to try her out .

Humbly, B-Stone

tpeever · Apr 27, 2009

Did you change valve timing during the rebuild? I spent a LONG time trying to get my Triumph TR6C started after a complete rebuild only to find out that the markings on the timing wheels were all wrong!! After I figured out the valve timing from first principles using a degree wheel, all was well. For Nortons, you need to have the correct number of chain links between the timing sprockets and your cam chain at the appropriate tension.

The other thing that springs to mind is ignition timing. Have you checked using a TDC tool and a degree wheel to set the static timing on the Boyer pickup plate? Don't rely on rotor marks. Make your own that you know are spot on. Once you know valve and ignition timing is perfect, you can start looking at other potential causes.

B-Stone · Apr 27, 2009

Hmmmm....well after attempting to set the valve clearance it became very obvious that there is something else wrong. I would set it, hand crank over, recheck and it woudl be tight again. Repeated this multiple time on the intakes (both sides) and same problem. Kept tightening up no matter how tight I locked the nut downwhile keeping the adjuster steady.

Decided that the head has to come back off. I am starting to wonder if:

a. I mixed up the push rods when I re-assembled and put the short where the longs go etc; and/or

b. the head was not down tight enough and was slowly lifting up; and/or

c. I put the push rods in upside down or something stupid

I only say this as I pulled the bike apart less the one centre bolt and some felt a bit lose for my liking. I did torque up the ones I could getthe wrench in on, the rest were best guess.

Hopefully I will get the head off tomorrow and see what is up. On the up shot, I am getting wicked fast as getting the bike stripped down! :lol:

BillT · Apr 28, 2009

I don't think you could swap or invert the pushrods - they're a ball on one end and a socket on the other, and an inch different in length between intake and exhaust. Sounds like the head isn't fully torqued down.

Check your cylinder base nuts, too.

B-Stone · Apr 28, 2009

Spoke with an excellent Norton mechanic I know. He indicated that the culprit is likely the cam followers being sticky. Recommended that I oil the pushrods from the top and let the oil work down to the followers beofre I take it back apart.

Will give that a try tonight.

Cookie · Apr 28, 2009

I am sure you know better, but one thing I've personally seen is a person setting the clearance at the wrong point of the timing cycle.

79x100 · Apr 28, 2009

It's been mentioned on the forum before that despite what the workshop manual says, the pushrods can sit outside of the cups in the followers, with the consequence that they can clip the other follower as the motor turns over.

Many of us seem to have found this out the hard way.

If you've fitted new followers then they probably will be too tight. They seem to be made oversize to take up wear and generally need lapping into the tunnels.

chris plant · Apr 28, 2009

hi b stone,if you fitted new followers you should have checked that they were free in the tunnels, you should be able to push them up with finger pressure and be able to slide back down under their own weight after being lubed with oil that you are using

B-Stone · Apr 28, 2009

The head was re-conditioned to 60 thou over so I didn't take the followers out. Not sure if they did but I do remember that they looked fine when I handed it over. I had it sitting in my garage for a couple of months wrapped in saran wrap when the weather was brutal so I figure it is possible that they have just got a bit stuck or, worst case, there is crap in them from the bore out.

If no joy on lubing them I will take the top off and inspect the rods and see if they can be manually worked to feel he followers. If this still doesn't work then I guess I pull the bottom and inspect the followers up close and personal.

Thanks as per for the great sugegstions!

Damn bike won't start!

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