Won't start.

[SteveD]

I thought it was running a little rich. Smelled of petrol a little too much, started with full choke at the first press of the button, choke to half ride off and then off at 2 kms...or thereabouts. Ran like a stream train too.

So went for a warm up ride and tweaked the tune, from mixture, idle speed and cables.

Coming home it stuttered on transition.

Next day, wouldn't start.

Investigations include: checked settings. Put everything back to starting setup. Mixture screws to 1 turn out, idle screw gap set at 0.07 via feeler gauge, then turned CW in 1 full turn. Left the cables. They've got 2mm free play about where it was before anyhow.
Removed the jet stacks. All newish but some gunk on one. Cleaned and put back. MJ 165, NJ 2.66.

I've also varied the mixture setting from 0.75. 1.0, 1.25 turns out. It was around 1.0 previously.

Throat holes blasted with carb cleaner and fishing line into the orifices. Mixture screw hole and the pilot jet holes.
Starter jets in bowels bowls clear, bowl gaskets in good condition and sealing well.

Battery cranked well, but eventually ran out of juice.

Plugs look tan and good, Bosch, been in 6 months or so.

Fuel just a few days old.

Still won't start using the usual choke/closed throttle/ignition/engine catches/throttle open technique.

To top it off and to confirm the "if it ain't broke mantra" I found the lower fuel hose had a slight leak, enough to cause the odor.

[Deleted User 62]

Did you confirm that you're getting spark?

[Major Softie]

[img]
Starter jets in bowels bowls clear, bowl gaskets in good condition and sealing well.

Thanks for that, Steve.

I agree that we need to know if you've checked for spark, but we also need more info than "won't start." Does it fire at all, chuff a little, absolutely nothing like the kill switch is on, what?

By the way, the kill switch isn't on, is it?

[SteveD]

Kill switch is off.

Battery cranked well, but eventually ran out of juice.

It sounded like it wanted to start, just kept churning over.
Spark is bright.
Battery reads 12.72 before ignition is switched on.

It had always started very easily. All I did the other day was to adjust carb settings.

I might set the tappets at 6 & 8 and see what happens.

[Jean]

AND right after you adjusted the carbs, it started acting balky and NOW won't run.
Sounds like a "message" there.
Assuming you've got Bings (?) so time to check the bowls (really the bowels...!) again and especially that little chamber where the starting device takes its fuel; that little hole in the bottom just might be stopped up for some mysterious reason.

The comment about the tappets: Did you also adjust them? Didn't mention that in the first post.

[SteveD]

AND right after you adjusted the carbs, it started acting balky and NOW won't run.
Sounds like a "message" there. Yep...go to the last thing done. That's why I wasn't concerned re: spark etc.
Assuming you've got Bings (Yep) so time to check the bowls (really the bowels...!) again and especially that little chamber where the starting device takes its fuel; that little hole in the bottom just might be stopped up for some mysterious reason. That was done.

Starter jets in bowels bowls clear,

The comment about the tappets: Did you also adjust them? Didn't mention that in the first post. A while back. Did them a little tighter than usual then. Just wondering if normal clearances might make a difference?

[jagarra]

You mentioned a leak in one of the fuel lines. If you pull the line from the carb and turn on the petcock, is there a strong flow of fuel. I guess the question is how is the condition of the fuel lines, are you turning on both sides?
Have you pulled a bowl to see how much fuel ends up in there?

[Ken in Oklahoma]

Sometimes, when I'm vexed (I just like that word) by a problem, I call to mind a sort of mantra:

If an engine has fuel, compression, and spark at the right time--it HAS to run.

As trite as that saying might be, it seems to focus my thinking a bit when I'm trying to find some direction.



Ken

[Major Softie]

Sometimes, when I'm vexed (I just like that word) by a problem, I call to mind a sort of mantra:

If an engine has fuel, compression, and spark at the right time--it HAS to run.

Ken

Air. Pretty sure it has to have air.


Ken, as completely and unassailably true as that is, in my limited experience with Brit bikes, I have found that they somehow manage to defy the unassailable. Beemers, however, seem to be more responsive to simple laws of physics.

[jagarra]

As my old boss used to joke with me, "most carburetor problems are electrical" so in this case it also matters when you get your spark. The thing that is most concerning it the abruptness of the symptom. Just tweaking a carb screw shouldn't cause this much of a problem.